Chilled Water Buffer Tank Sizing

A Chilled Water Buffer Tank Sizing Guide for Optimal System Performance

If you’re looking for the best approach to sizing a chilled water buffer tank or vessel, you’ve most likely seen chillers cycle because the buffer vessel or tank is too small.

Have you ever been annoyed by temperatures that fluctuate as your load changes? As the load decreases, the room’s temperature drops abruptly.

The system fails due to a low temperature fault, necessitating a service call to the location to complete the reset. In addition, there is a possibility of flooding back and oil buildup in the compressor, among other potential issues.

Perhaps your problem was the opposite: going much over budget for an 8,000-liter buffer tank when you only needed half that volume.

Calculating the buffer tank size required for your chilled water system may appear to be a daunting undertaking, but getting chilled water buffer tank sizing right is essential for your chillers and other equipment requirements for your hvac system and customer satisfaction.

The chiller manufacturer should be your first stop, because all chillers can have nuances. Nobody knows their chillers better than they do, so our advice is to contact them first for a recommendation.

When is it appropriate to use a chilled water buffer tank?

A chiller requires a particular system volume to function in low-load mode without cycling.

Cycling can occur in low-load situations, such as when everyone who works leaves the premises at the end of the day.

The building load significantly decreases, necessitating an increase in the system’s volume to avoid cycling and subsequent damage to the chiller.

Identifying scenarios that require a buffer vessel or tank for chilled water

  • Water chillers require a certain system volume to operate in low-load conditions without cycling.
  • If the total system volume (TSV) is less than the chiller manufacturer’s requested capacity, a buffer tank is required.

The benefits of using a buffer vessel or tank in chilled water systems

  • Prevents temperature fluctuations and system cycling.
  • It ensures optimal chiller performance, improves energy efficiency and prevents potential damage.

Buffer Tank Sizing Fundamentals

Understanding the variables that affect the size of the buffer tank is crucial.

  • Determine the kW rating of the chiller and the necessary system capacity.
  • The total system volume (TSV) encompasses the water capacity volume of the chiller, pipe system, and buffer tank.
  • Flow rates and desired temperature fluctuations.

The formula: calculating buffer tank size accurately

First,the chilled water buffer tank sizing rule of thumb

  • Chiller manufacturers can differ in their system volume needs; however, four litres per kW seems to be the normal ratio for air conditioning system comfort control applications. Thus, chiller kW x 4 litres = required system capacity (litres).
  • However, multifunction chillers can be up to 11 liters/kW. This is due to the need to balance the heating and cooling within specific limits, which complicates the system and necessitates the additional volume.

Then the accurate calcualtion is:

  • Required System Capacity (L) – Total System Volume (L) = Required Buffer Tank Volume (L).

V=N x 60 x Z / 4.18dt

V = total system water content (litres)
N = the chiller’s first capacity step (kW).
Z = the minimum allowable running time (minimum 5 minutes).
dt represents the temperature difference at the minimum part load condition, which is, for example, 2 °C.

This allows the chiller to operate smoothly at low load capacities, and it should provide sufficient thermal storage to offer at least 5 minutes of operation after the unit has stopped running.

The Role of Bypass Valves in Buffer Tank sizing

The positioning of the bypass valve is important; it can’t be too close to the chiller.

  • To avoid damage from cold water flowing back into the chiller, position the bypass valve far enough away from the chiller.
  • The valve should be positioned to ensure the volume of water enclosed in that section of pipe meets the specification or minimum volume of water required by the chiller.

How do bypass valves affect the total system volume?

  • The TSV used in the buffer tank volume calculation should be adjusted based on the length of pipe required for the water to come out of the chiller and return through the bypass.

Avoiding Common Sizing Mistakes

The consequences of undersizing a chilled water buffer tank are significant.

  • There are temperature fluctuations, system cycling, and potential damage to the chiller.
  • Adjustments to the BMS and installing additional valves may help temporarily, but they cannot solve these problems.

Strategies for preventing undersizing

  • Use the correct formula to calculate the required buffer vessel or tank volume.
  • Consider variables such as flow rates, desired temperature fluctuation, and chiller kW rating.

Choosing the Right Buffer Tank

The process of determining the buffer tank capacity involves taking into account the stabilisation of the system and the actual water level.

  • Calculate the water required for system stabilisation using the formula:M1 = QT / (C △ T), where Q is the unit’s heating capacity (in KW), T is the defrost time (in seconds), C is the specific heat capacity of water (4.187), and △ T is the maximum allowable drop in water temperature (in °C).
  • The actual water volume of the system is the sum of the water capacity per meter of the floor heating pipe and the total length of the system pipe, including the water capacity of radiators.

Then look at this webpage for our range of chilled water buffer vessels or tanks and select your appropriate buffer vessel for chilled water

Material considerations, installation guidelines, and maintenance tips

Consider material options such as carbon steel or stainless steel.

Ensure proper installation and maintenance to prevent corrosion and damage.

Regularly inspect and clean the buffer tank to maintain optimal performance.

Electric multipoint water heaters

Electric Multipoint Water Heaters for Instant Hot Water

Electric multipoint water heaters 9kW to 36kW from Flexiheat UK

 

Electric multipoint water heaters are an excellent solution for supplying hot water to multiple points with an instantaneous water heater.Thus the term “multipoint instantaneous water heater”

Our multi-point electric water heaters have state-of-the-art heating technology, allowing for precise temperature regulation to provide personalised comfort. Typically, our units with a rating output of up to 27 kW come with digital displays and adjustable temperature settings for easy water temperature monitoring and adjustment.

This multipoint instantaneous water heater range is typically used in domestic and commercial applications such as shops, factories, student accommodation, etc., supplying hot water for one outlet or multiple outlets, depending on the flow rate of the shower or taps (sink taps for dishwashing, food preparation, etc. or toilet-type taps) being used.

What is an Instantaneous Electric Water Heater?

  • An instantaneous electric water heater is a type of water heater that provides hot water on demand, without the need for a storage tank.
  • It heats water instantly, using electricity, and supplies it to various points of use, such as sinks, showers, and basins depending on the flow rates required.
  • Instantaneous electric water heaters are ideal for residential and commercial applications where water heating is required quickly and efficiently with energy savings compared to storage water heaters.

Benefits of Multipoint Water Heaters

  • An electric multi point water heater,which is a tankless heater provides hot water on demand, eliminating the need for storage water heaters.
  • Energy-efficient, as they only heat water when needed.This instantaneous water heater range all have a ErP “A” energy rating.
  • Suitable for multiple points of use, such as sinks, showers, and basins or to provide instant hot water for an appliance such as a dishwasher or washing machine.
  • Compact design, ideal for small spaces or remote areas for point of use such as a sink or shower that require instant hot water.
  • These multipoint electric water heaters can be used in commercial water heating settings, such as offices, restaurants,student accommodation and hotels.

Key features to consider for instantaneous electric water heating

  • Look for an instantaneous water heater with a suitable power rating (the kW rating) to meet your hot water needs.
  • Safety features: Ensure the multipoint hot water heater has features such as a high temperature cut out, which is a safety cut out.
  • Multiple points: Consider a water heater that can supply hot water to multiple hot water outlets / points of use.
  • Check the flow rate of the water heater to ensure it meets your hot water needs.

Choosing the Right Size and Type

Consider the number of points of use and the flow rate required.

Choose a water heater with a suitable power rating (in kW) to meet your instant hot water needs.

Overview of the product, including its features and benefits.

Review of the product’s performance, including its flow rate at your required water temperature increases , the maximum water temperature it can produce, and energy efficiency.

Flow rates for hot water fixtures

Standard shower head: 7 to 8 litres per minute flow rate

Standard shower head 7 to 8 litres a minute flow rate

Standard shower head 7 to 8 litres a minute of flow @ 40C

A standard shower head requires 7 or 8 litres of hot water per minute, whereas European Water Label “green band” water-saving shower heads require 6 litres per minute. Think of this standard as an “ErP” rating for bathroom products, taps, etc.

Kitchen sink taps: 4 to 6 litres per minute

The “spray taps” for basins and sinks range in capacity from 2 to 4 litres per minute.

Be careful to check the flow rates on your spray taps, as all our instantaneous water heater units require a minimum flow of 2.5 litres per minute to operate.

Modern bath mixer taps have an approximate demand rate of 12 litres per minute.

Please note:

Drench showers with hot water flow rates from 15 to 30 litres a minute

Please be aware that drench showers can have massive flow requirements, ranging from 15 litres to pretty much any flow rate; 30 litres per minute for a drench type shower is not uncommon. For these water heating applications,a large instantaneous water heater will be required or even a direct storage unvented DHW cylinder due to the high volume of water required to feed this type of shower

Product range

These instant water heaters feature four power ratings or output ranges in a single unit. The 27kW and 36kW electric multipoint water heater, on the other hand, only offers a single power setting.

For instance, you can choose between the 17kW, 18kW, 21kW, or 24kW power outputs on our 17kW to 24kW instantaneous water heater.

This affects the draw-off point flow rate; therefore, at 17 kW, it will produce 8.1 litres; at 24 kW, it will produce 11.6 litres a minute, at the standard temperature rise of 30 °C, for daily use in the winter period, as that’s when you want hot water the most, as you can see in the following data table.

Power output of the instantaneous water heater9kW to 15kW power rating17kW to 24kW power rating27kW36kW
Energy efficiency classAAAA
Heat capacity ( power setting options)9/11/12/15 kW17/18/21/24 kW27 kW36kW
Electrical supply – All require a 3 Phase power supply 400V 3N~400V 3N~400V 3N~400V 3N~
Mains water supply pressure (Bar) min – maximum1 to 101 to 101 to 101 to 6
Hot water flow rate at  Δt=30 in litres per minute4.3/5.2/5.8/7.28.1/8.7/10.1/11.61317.3
Rated current (Amps)3×13/15.9/17.3/21.73×24.6/26/30.3/34.63 x 393 x  39.9
Dimensions – W x D x H (in mm)245 x 126 x 440245 x 126 x 440245 x 126 x 440315 x 140 x 492

Please note that our instantaneous water heater range requires a minimum flow rate of 2.5 l/min to start heating the water. They will not operate if the flow is lower than this point.

For a given kW output from the hot water heater – as the water temperature increases, the flow rate decreases is the basic rule of physics.

The 9kW to 27kW have a digital display

Digital display on our instantaneous electric water heaters from 9kw to 27kW from Flexiheat UK

The digital display on our 9kW to 27kW instantaneous water heater range

Download the 9kW to 27kW multipoint instantaneous water heater range manual

and our 36kW unit has a tradtional temperature dial

36kW electric instant water heater from Flexiheat UK

36 kW Electric instant water heater – with a manual temperature control dial

 

Download the 36kW Electric multipoint instantaneous water heater manual 

Installation and safety considerations

  1. Make sure a qualified electrician installs the water heater.
  2. Follow the manufacturer’s installation guides and instructions to ensure the warranty.
  3. Ensure the instantaneous water heater is located (wall mounted) in an area with adequate space to service or inspect the water heater and as close as possible to the water outlets being served.
  4. The water heater must not be installed in a site that is exposed to the danger of an explosion and where the temperature might drop below zero C, as the water in the heater will freeze and damage the water heater, which will invalidate the warranty.
  5. Check the water heater’s safety features, such as the high temperature cut out i.e., a safety cut out to prevent overheating.
  6. No pressure relief valve is generally required on an instantaneous water heater unless the water pressure can get above the 10 bar the 9kW to 27kW models are rated for.The 36kW water heater is rated to a maximum water pressure of 6 bar.
  7. No Expansion vessel is required for an instantaneous water heater, as they supply instant hot water there is no hot water storage to account for unlike tank-type water heaters.

Energy Efficiency and Running Costs

Instantaneous electric water heaters are energy-efficient, as they only heat water when needed.

Look for a water heater with a high energy efficiency rating- Our electric multipoint instantaneous water heaters have an “A” energy rating.

Consider the running costs of the water heater, including electricity consumption and maintenance costs.

Contact us

Should you require further assistance, check stock (we normally have the units on the shelf for the next working day delivery or express delivery times i.e. timed, weekend etc), or get prices on our energy-efficient and cost-effective electric multipoint water heaters with accurate factory fitted temperature control and , then please don’t hesitate to call our sales team on 01202 822221 or click here for our email contact form.

For your heat pump system, is a thermal buffer tank necessary?

For your heat pump system, is a thermal buffer tank necessary?

A buffer vessel, sometimes referred to as a buffer tank or thermal storage tank, is an element that enhances the performance and efficiency of most air source heat pump (ASHP) systems.

In essence, the buffer vessel is a thermal reservoir comprised of a tank filled with water. Decoupling the heat pump from the cooling or heating distribution system is its main purpose, and it offers the following advantages:

Enhancing Heat Pump Performance:

By enabling the heat pump to run at maximum efficiency for longer periods of time, buffer tanks can raise the system’s overall efficiency. System performance may improve, and energy savings may arise from this.

Reducing Cycling:

The heat pump’s on/off cycling is lessened using buffer vessels. Continuous operation at a constant load is the most efficient operation for air source heat pumps. The need for heating or cooling in a structure can, however, differ. The buffer tank keeps the heat pump from starting and stopping frequently, which can result in poorer efficiency, and enables it to run at a constant output for longer periods of time.

Improving System Stability:

The heating or cooling system is more stable when buffer vessels are used. When demand is low, they retain the heat pump’s extra energy and release it when demand is high. This contributes to a more constant and cosy interior temperature.

Enhancing System Control:

By providing a volume of water that can function as a thermal mass, buffer tanks help to slow down the rate at which the water’s temperature changes. This may facilitate more accurate control over the heat pump’s performance and better temperature fluctuation management by simplifying the system’s overall control.

Reducing Wear and Tear:

The heat pump’s components may experience wear and tear because of frequent cycling. By lowering the quantity of on/off cycles, the buffer tank helps to prolong the heat pump’s lifespan and lower maintenance needs.

Three key points for the use of buffer tanks in heat pump systems

  • Increasing the amount of water in the heating system is the aim. By preventing short cycling, buffer tanks balance the system and ensure that the heat pump operates well. In the absence of a buffer tank, the heat pump constantly modifies its operation by turning on and off, which increases wear and tear, particularly in unpredictable spring and autumn weather.
  • A heat pump system’s two circuits can operate simultaneously as independent and cooperative units thanks to buffer tanks.Why is that relevant? To function optimally, the two circuits require distinct flow rates and temperatures. The circuit for “giving out heat” (such as radiators or underfloor heating) shouldn’t use the same logic as the heat pump circuit.
  • By supplying heat from the buffer tank to aid in the defrosting process without drawing heat from the house’s radiators, the buffer tank helps the heat pump defrost cycle.

Additional benefits

The heat pump compressor is successfully shielded by buffer tanks against excessive strain and expensive failure.

Similarly, in the absence of a buffer tank, a heat pump system will need to provide extra heat through radiators and/or underfloor heating.

In addition, homeowners who do not have a buffer tank lose out on the opportunity to zone their heating, fully regulate the heating system, and switch off the heat in specific rooms. In the long run, a system without a buffer tank may be less expensive overall, but it will also be less comfortable and possibly overheated.

Conclusion 

Not every air source heat pump system will need a buffer vessel. The particulars of the building, the anticipated fluctuations in demand, and the heating or cooling system’s design all influence whether a buffer tank is necessary. It can be determined whether a buffer vessel is required for a certain ASHP installation by speaking with a heating system expert, however, they generally benefit a heat pump and the HVAC system.

For our full range of buffer tanks from Flexiheat UK, please see the following webpage: Buffer tanks

2000 Litre Buffer tank or Vessel

2000 Litre buffer tank or vessel

 

 

What is a buffer tank?

First, we must clarify what a buffer tank does, as they are ideal for use in renewable and traditional heating systems, including gas, biomass, or oil boilers, as well as solar thermal and heat pumps (both air source and ground source heat pumps).

 

Definition and purpose of buffer tanks

A buffer tank retains thermal energy via thermal storage for later use and can supplement the heat source when demand is high or store heat (heat sink) when demand is lower. Stored energy in the form of heat can be immediately accessed without the heat source needing to get up to temperature, which is useful for maintaining a constant output over time for your heating hot water systems.

 

The benefits of using buffer tanks in heating and cooling systems

Buffer tanks provide a reliable and efficient heating solution because they store heat for later use by the heating system. They can decrease the number of on/off cycles of the heat pump due to stored heat in the buffer tank or vessel.

For chilled water thermal storage systems, which are often used in air conditioning systems to improve thermal inertia, the buffer tank is insulated in such a way as to keep the temperature as low as possible.

All of our buffer tank ranges have high thermal insulation levels and comply with the ErP insulation requirements, which cover buffer tanks up to and including buffer vessels or tanks up to 2,000 litres in volume.

Conformity to standards

All of these buffer tanks comply with both Article 4 , Paragraph 3 of the Pressure Equipment Directive (PED) 2014/68/UE and the ErP Directive EU 812/2013 for energy-related products.

Buffer tank options for 2,000 liters of heated or chilled water

We have two main options: hot water storage (2000 litres) or chilled water storage (2000 litres).

Option 1

Our “PSS Buffer Tank Range” has two standard options: one buffer tank that is suitable for both heating and chilled water systems, and one buffer tank that is only suitable for chilled water systems.

Both options have six  x 4″ female BSP tappings and 3 x 1/2″ female temperature probe or gauge ports on the buffer tank.

With a maximum working pressure of 6 Bar and maximum temperature of 95°C  for both buffer tank options.

A diagram showing the connections of our 2000L buffer vessel for heating and chilled water with a maximum working pressure of 6 bar and 95C temperature from Flexiheat UK

2000L Heating or Chilled water buffer tank -PSS range with 6 connections

 

The heating and chilled water version has 80mm polyester with 20mm PEXL insulation. This is a polyethylene foam that stops water vapour diffusion, protecting the buffer tank exterior from dew and corrosion. Because of its extremely low water absorption, the lagging effectively doesn’t absorb any water. This results in a class “C” ErP insulation level for the material.

Technical data showing the connections on our 2000 litre buffer vessel or tank for heating or chilled water from Flexiheat UK

Both the 1,500 Litre and 2000 Litre buffer tanks – have the same connection sizes.6 Bar working pressure (unlike many of our competition which only offer 3 Bar working pressure)

 

Since chilled water units do not fall under the ErP regulations, the chilled water buffer tank option only has 25-mm PEXL insulation.

Download the PPS Buffer tanks for heating and chilled water – 25 litres to 2,000 litres capacity brochure from Flexiheat UK 

Option 2

Our “MV” or “MXV” range of buffer tanks is for both closed heating and cooling systems.

2000 Litre buffer vessel or tank MV mild steel or MXV stainless steel models from Flexiheat UK

MV or MXV buffer tanks

Both buffer tank options are rated to:

Maximum working pressure: 6 bar

Maximum working temperature: 110 ºC

The “MV” buffer tank range is manufactured in mild steel, while our “MVX” buffer tank range is manufactured in 304 stainless steel and offers higher durability and resistance to corrosion.

These tanks are thermally insulated with rigid, mould-injected (this system guarantees a perfectly regular insulation thickness with optimum material density), 80mm thick PU polyurethane foam insulation, with an insulation piece on the optional 400mm side manhole on the “IB” models. This thermal insulation is both CFC- and HCFC-free and fire-resistance class B-s2do according to EN 13501.

The products are ERP-compliant, offers a “C” rating as standard (EU 812/2013), and come with three years warranty.

Technical data for MV and MXV units

Both buffer tank options come with four x 4″ female BSP tappings (designated “S” on the above drawing) and various other tappings for temperature probes or sensors, temperature gauges, or working pressure sensors or gauges to be fitted to the tank.

Technical detail of our 2000 Litre buffer tanks or vessels in mild steel or stainless steel 304 from Flexiheat UK

“I” model – no clean out port – “IB” with 400mm clean out port

 

The buffer tank can optionally be supplied with a “UV” restitant PVC-padded external lining or “ALUNOX” aluminium sheet covering for external use. This is typically required or standard in coastal areas of the UK to prevent seagulls from pecking at the buffer tank’s insulation.

Each buffer tank option comes with a tapping for a backup electric immersion heater to be fitted to the tank if so required.

2000IB - 2000 Litre buffer tank with inspection and maintenance manhole in carbon steel or stainless steel from Flexiheat UK

IB Version – with inspection and maintenance manhole.

IB MODELS: A side 400mm manhole provides access to the inside buffer tank for tasks such as inspection, cleaning, and maintenance.

These buffer tanks are detailed on page 11 of the following brochure:

Download the Buffer tanks for thermal storage for heating or chilled water in HVAC systems brochure from Flexiheat UK

Heat Exchanger Coil Options

We also do a range of buffer tanks that have an intermediate coil or coils within the tank to hydraulically separate the heating or cooling source from the water in the buffer tank. You can think of these as large “low loss headers” or an indirect water heater which offers the guarantee that any heating system sludge from an existing system is prevented from entering the heat pumps, biomass boilers, solar, or geothermal systems.For further information on this range of buffer tanks please see here: Buffer tank with coil or twin coils

buffer tanks for heat pumps; cylinders buffer vessels; heating; heat pump buffer

Please note that these are not domestic hot water cylinders for the production of domestic hot water for commercial water heating; we supply these water heaters or calorifiers, and these are listed on this webpage: commercial domestic hot water calorifiers

System requirements and compatibility: ensuring the right fit

The system requirements and compatibility of the buffer tank should be considered, including the working pressure, insulation,insulation and tappings.

These buffer tanks are ideal for the specific application, whether it’s for biomass, air source heat pump, ground source heat pumps and gas, wood pellet, gasification, or oil boilers.

The budget and cost of the buffer tank should be considered, including the price of the tank and any additional features required.

Regular maintenance and upkeep of the buffer tank

Regular maintenance and upkeep are essential to ensure the longevity of the buffer tank. Tips for maintenance include checking the tank’s insulation and working pressure.

Contact us

At Flexiheat UK, our technical sales staff are available to provide support, further information, or to place an order for our 2000 Litre buffer tank or vessel options for hvac systems. Speak to us on 01202 822221 from Monday to Friday, 9 a.m. to 5 p.m., or email us via our Contact Page.

Three phase water heater options

Three phase water heater options

Three phase water heater / water heater 3 phase options - instantaneous water heater or tankless water heaters and duplex stainless steel storage hot water systems from Flexiheat UK

Our three phase water heater range of instantaneous water heaters are the perfect solution for instantaneous water heating with a three phase electric supply. We also do a 3 phase water heater with stored hot water options for applications where an instantaneous water heater can’t handle a peak domestic hot water demand and thus an element of stored water is required.

Efficient hot water supply is crucial for commercial and industrial applications. Instantaneous water heating is the most energy-efficient way of producing hot water electrically. Three phase water heater’s offer a reliable and efficient solution for domestic hot water supply.

Three phase power

An electrical system’s phase determines the distribution of a load. What’s the distinction between single-phase and three-phase power supplies? A single-phase power circuit features two wires carrying alternating current (AC).

Typically, there is one power wire, known as the phase wire, and one neutral wire, with current flowing between the two. Three-phase power is a three-wire alternating current power circuit in which each phase AC signal is 120 electrical degrees apart.

Businesses and factories typically use a three-phase power supply, while residential homes typically use a single-phase power supply.

One significant distinction between single-phase and three-phase power sources is that a three-phase power supply can handle larger loads and power ratings that are required for three phase hot water systems.

Instantaneous water heater: hot water on demand

3 phase instantaneous water heaters are a great option for lower hot water demands. We have a full range of instantaneous water heater products that benefit from bare wire water heating technology (heating elements) for maximum energy efficiency and accurate hot water outlet temperature from the appliance for multiple draw off points.

Electric instantaneous water heaters are energy-saving on demand instant water heaters and are also called an electric tankless water heater - from 9kW to 27kW output from Flexiheat UK

These units are sometimes referred to as three-phase tankless water heaters, 3 phase instant water heaters, or a 3 phase electric instantaneous water heater.

The two smallest instantaneous water heaters – can be set to various outputs i.e. our 9kW to 15kW water heater can be set to either 9,11,12, or 15 kW to suit you water heating requirements.

Power output of the tankless water heaters9kW to 15kW Output power rating17kW to 24kW Output power rating27kW instantaneous water heater36kw instantaneous water heater
Energy efficiency classAAAA
Heat capacity ( power output setting options)9/11/12/15 kW17/18/21/24 kW27 kW36 kW
Power supply – Voltage 400V 3N~400V 3N~400V 3N~400V 3N~
Mains water supply pressure (Bar) min – maximum1 to 101 to 101 to 101 to 6
Hot water flow rate at  Δt=30 in litres per minute4.3/5.2/5.8/7.28.1/8.7/10.1/11.61317.3
Rated current (Amps)3 x 13/15.9/17.3/21.73 x 24.6/26/30.3/34.63 x 393 x 52
Dimensions – W x D x H (in mm)245 x 126 x 440245 x 126 x 440245 x 126 x 440315 x 140 x 492

Please note that the maximum water temperature this 3 phase instantaneous water heater range can produce is 60 °C. If your require higher water temperatures, then you need to look at our storage water heater option.

We stock these instantaneous water heaters and if order early in the day they can be sent on a next working day delivery service or even for a Saturday delivery at extra cost.

We go into full depth on this dedicated webpage about our electric instantaneous water heaters, which are all 3 phase powered. Here – Electric instantaneous water heaters

Storage three-phase hot water systems

Sometimes you’re going to need a storage water heater rather than an instantaneous water heater, as your water heating requirements or peak load are just too large for an instantaneous water heater to be able to cope with.

We offer a comprehensive selection of 3-phase-powered storage water heaters in duplex stainless steel (which has the best corrosion resistance), ranging in capacity from 80 litres to 1,380 litres, compatible with various stainless steel immersion heaters up to 108 kW in power.These immersion heaters come with a temperature regualtion thermostat and saftey thermostat.

commercial electric water heaters; commercial electric hot water heater; industrial electric water heater; industrial electric hot water heater;

Commercial & Industrial electric water heaters from Flexiheat UK

We offer a glass-lined or 316 stainless steel 3 phase water heater with a storage tank capacity ranging from 80 to 6,000 litres, equipped with immersion heaters capable of producing up to 400 kW of heating power so you can supply multiple draw off points. This water heater range can produce water with a maximum temperature of 80 °C, which is more than our electric instantaneous water heater range, which is 60 °C.

We go into more depth on our 3 phase electrical powered storage water heater range here – 3 Phase storage water heater range

Contact us

Should you require further assistance or information on our three phase water heaters, then please contact our sales team on 01202 822221 or click here for our email contact form.

24kW Electric Boiler

24kW Electric Boiler

24kW Electric boiler from Flexiheat UK

Electric boiler 24kW Output options

A 24kW electric boiler is a highly efficient and cost-effective alternative to oil, solid fuel, natural gas, or LPG boiler systems and even electric storage heating.

They are the ideal alternative for properties without mains gas supply and residences with gas boiler limitations or gas boiler restrictions, such as listed buildings or being sited in a bedroom, etc. An electric boiler can be used for a radiator wet central heating system and is also suitable for hot water underfloor heating systems for medium or small properties.

You will require a three-phase electric supply to be able to run the boiler; they do not make a single phase electric boiler at 24 kW of boiler output.

Our range of electric boilers can also be coupled to an indirect hot water storage cylinder to provide domestic hot water for hot water outlets such as showers, bath taps, or sink taps.

Our 24kW electric system boiler option has all the components required for a sealed heating system, such as an expansion vessel and an ErP-compliant modulating pump.

These boilers are not suitable for open-vented systems.

An eco-friendly heating and hot water solution

When you produce (such as a photovoltaic system, i.e., solar panels) or buy renewable electricity or “green” electricity from renewable sources to run your electric boiler, your electric heating system is carbon neutral and not impacting the environment.

When operating electric boilers, they emit no combustion gases or noxious fumes, unlike traditional gas boilers or oil boilers, as there’s no flue requirement with an electric boiler.

Electric boilers, with easier installation, are a very cost-effective alternative to existing tank-based fuels such as oil or LPG boilers and heat pumps. Air source heat pumps are expensive, and ground source heat pumps even more so, as the installation costs are extreme, to say the least, especially when compared to electric boiler installation costs, even when an upgrade to a three phase electric power supply is required.

Benefits

  • Compact units compared to typical oil, solid fuel, or gas system boilers
  • No mains gas supply to run to the boiler, only electrical cables.
  • No bulky external tank that you require when heating with oil or LPG systems.
  • Operates quietly—virtually silent
  • No chimney or venting system is needed, making them a perfect solution for listed buildings or medium to small properties that may have gas boiler restrictions.
  • No danger of carbon monoxide poisoning; there is zero risk.
  • Superior inner design that includes a built-in pump for sufficient flow rates for radiators or underfloor heating circuit and an expansion vessel for the heating system
  • Suitable for wet central heating, either radiator or underfloor heating systems
  • Can produce domestic hot water via an indirect hot water cylinder for sufficient flow rates to serve your hot water outlets.
  • Easy-to-use touch screen control panel interface for superior performance
  • Can be used with renewable electricity from renewable sources such as photovoltaic system, wind or water generated electricity etc.
  • Operating temperatures up to 80 °C
  • Running costs are reduced due to the high modulation of the heating system.
  • Electric boilers are a very cost-effective alternative to heat pumps, gas and oil boilers, or electric storage heating.
  • When operating electric boilers emit no harmful gases, fumes, or pollutants.
  • Warranty – 2 years
  • Only suitable for properties with three phase electrical supplies

24kW Electric Combi Boiler

We also offer a 24kW electric combi boiler, a boiler capable of providing space heating and instantaneous domestic hot water. You can find this electric combi boiler range from Flexiheat UK on its dedicated webpage electric combi boiler range from Flexiheat UK. Please note that you will require a three-phase electric power supply to run an effective electric combi boiler. Our 24kW electric combi boiler will produce an instantaneous domestic hot water flow rate of 12.8 litres per minute with a temperature rise of 30 °C (the DHW temperature outputs range are adjustable from 30 °C to 55 °C). This flow rate is sufficient to fill a bath tub in a suitable timescale. They do not make a 24kw electric combi boiler in single phase.

Electric combi boilers really require a 3 phase power supply to produce an adequate domestic hot water flow rate. It’s as simple as that.

24 kW Electric boiler outputs options

The first question is why a 24kW boiler? Well traditionally the smallest gas boilers were 24kW in output and many people assume that this is the smallest boiler available in electric. This is not true, as they go all the way from the smallest output of 0.5 kW all the way up to 45kW for our domestic size electric heating boilers.

So, if you’re replacing a gas or oil boiler that’s 24kW – then the first thing you should do is check that this boiler isn’t oversized for your location – please see this webpage for guidance – What size electric boiler do I need?

We have a couple of options for around 24kW of output – these are

Our Model FHEL23, which is a fully modulating boiler – this unit has a maximum output of 22.5 kW – and will ramp up and down the following outputs to suit the heating demand of the system. Modulation range / power steps = 2.5,5,7.5,10,12.5,15,17.5,20 or 22.5kW

 

24kw output electric boiler option A from Flexiheat UK

FHEL23 boiler, with low heat output modulation – Output can be set to either – 2.5,5,7.5,10,12.5,15,17.5,20 or 22.5kW

 

The second option is our FHEL30 unit – this unit’s maximum heating power is 30kW – however this unit can be set to a maximum of 25kW output, so ever slightly over the 24kW, and the unit will ramp up and down this scale to suit the heating demand.

Output can be set to either 5,7.5,10,15,17.5,20,25,27.5 or 30kW

FHEL30 option for an electric boiler output of 25kW:electric boiler specialists installation

Please note – a heating expansion vessel need to be fitted external to the unit for this size boiler to make it a system boiler

 

The Amps required to power the unit at 25kW output is calculated as follows –

For Three Phase /415 Volt / 50 Hertz AC Circuit, that we use in the UK, then the calculation is –

Amps = (kW × 1,000) ÷ (√3 × volts)

Amps = (25 × 1,000) ÷ (1.73 × 415)

Amps = 25000 ÷ 717.95

Amps = 34.82 Per Phase – on the three phases of the electricity supply

Plus, you want to and the pump electricity requirements of one Amp per phase (3 Amps in total)

Thus, the maximum total electrical consumption would be 35.82 ( call it 36 Amps) per phase

The full brochure on these units is here –

Flexiheat Brochure For Electric Boilers

and the installation and technical manual is here –

Flexiheat Electric Central Heating Boilers – Installation & User Manual – FHEL Boilers

 

Domestic hot water production

Heating hot water for sanitary use – by using the heating electric boiler in conjunction with an indirect domestic hot water tank, you can supply plentiful amounts of domestic hot water for your bathing needs, be it showering, filling a bath, or washing up in the kitchen.

This hot water system ensures that the electric boiler does both your heating system and domestic hot water—the wet central electric heating system, be it radiators, underfloor heating, or a mixture of both and the domestic hot water via indirect cylinders. We refer to electric boilers in these circumstances as system boilers.

electric boilers for heating and hot water;electric boilers for hot water and central heating; electric hot water boiler system

A diagram showing how an electric central heating boiler is connected to a Domestic Hot Water Cylinder or Hot Water Tank

Control options

Using an appropriate controller on our electric boilers can produce superior performance and lower monthly running costs.

OpenTherm is a communication protocol between heating controls and the boiler to modulate the temperature flow through a heating system.

Since it’s a standard protocol, any “OpenTherm” controller, such as Nest, Hive, Honeywell, Drayton, etc., can work with our electric boilers. There are so many manufacturers now that if the controller says “OpenTherm,” it will work and help reduce running cost.

 

Contact us

Should you require further assistance or information on the best 24kW electric boiler on the UK market, that we normally have in stock for express delivery or standard delivery then please contact our sales team on 01202 822221 or click here for our email contact form.

50kW Combi Boiler – Gas combi boilers

50kW Combi Boiler / Combination boilers

A 50kw combi boiler or 50 kw gas combi boiler- which is a combination boiler doing both heating and domestic hot water heating, powered by either natural gas or LPG gas from Flexiheat UK

50kW Combi boiler or Combination boiler – gas fired – from Flexiheat UK

Our Flexiheat 50kW combi boiler is a well-designed condensing combination boiler with 97% efficiency, making it an “A” rated boiler for heating and hot water. This efficiency allows it to generate enough heat to meet your home’s demand while using less fuel than an older, inefficient boiler. The boiler installation is easy, and we can supply this high performance 50kW gas combi boiler in either natural gas (mains gas) or LPG (propane gas), which is ideally suited to larger homes with high demand and more than one bathroom or even multiple bathrooms, i.e., two or more bathrooms.

Gas combi boilers are a one-of-a-kind, compact, and cost-effective solution that are ideal for houses with limited space. They combine a water heater and a central heating boiler into a single device, eliminating the need for additional water cylinders, immersion heaters, or tanks in your large homes that you require with a system boiler and reducing installation costs.

Boilers account for approximately 60% of a household’s yearly energy costs for domestic use, and they have an enormous impact on fuel bills. With more seasoned older gas boilers, a significant amount of heat that could be used to produce hot water is wasted, making them increasingly expensive to run.

Our 50kW combi gas boiler is more than 97% efficient, so 97p of each £1 you spend on your energy bills for your boiler is utilized. When using an Opentherm internet-connected smart controller, you can control our ERP “A”-rated high performance gas boiler on the go from your mobile, or tablet—the right choice for people with busy lives in large homes and even commercial heating and hot water applications.

ERP “A” rated efficiency rating for both heating and hot water demands, this powerful wall hung boiler is an efficient and reliable combi gas boiler, that can comfortably heat large homes, providing effortless comfort at a reduced running cost. All while you sit comfortably in complete peace of mind, knowing that you have a highly efficient 50kw combi gas boiler, that is also one of the quietest boilers in its class at 52 decibels noise level installed (for comparison, a refrigerator is around 50 decibels noise level).

The best features of our condensing 50kw combi boilers / combination boiler are:

 

  • Higher kW boiler: compared to the competition, we actually make a 50kW combi boiler that will do 53.85 kW output rating of heating power based on a 50C/30C flow and return system, or 49.19 kW output rating at 80C/60C.

 

  • The central heating boiler side of this high efficiency powerful combi boiler can be used on an underfloor or radiator heating system. This makes this combi boiler great for large properties; we talk more about this application here – Combi boiler for a large house

 

  • Modern new design: this gas boiler benefits from aesthetically pleasing looks. With its modern design, and quieter operation with a reduced noise level, it is one of the quietest boilers on the market, with a reduced lift weight compared to the competition.

 

  • Increased burner modulation ratio of 1:10, which prevents on/off cycling for a lengthy product life for your new boiler and reduces noise level for the user.

 

  • It’s inbuilt intuitive controller, which benefits from an intuitive menu structure for all the information required for control, commissioning, and fault finding if so required of the heating system, which means no need to search through manuals for fault codes. Resulting in the rapid diagnosis of any issues. Not that you’ll use the fault finding much with our quality range of efficient 50kw gas fired combination boilers.

 

  • Servicing: With plenty of room within the appliance casing for easy internal access, this 50kW combi gas boiler is an installer’s dream to work on, with pipe connections at the bottom of the boiler and fixing points at the rear of the boiler. Also a benefit for rapid diagnosis and fault finding.

 

  • Installation of the gas boiler, which must be done by gas safe qualified installers or company – can be in any location, as we offer various flue options, such as a room-sealed range (see details below). Also, being one of the quietest boilers, you’ll have complete peace wherever you locate the boiler.

 

  • Can be operated on a system with an with an optimum pressure of 0.3 to 3 bars for the heating side and 0.5 to 6 bars for the domestic hot water side of the appliance.

 

  • This 50kW combi gas boiler is suitable for natural gas (mains gas) or LPG (must be specified at the date of customer order). Sit comfortably, knowing that if you change your gas type, these combi boilers are easily converted over.

 

  • Provide hot water. The DHW flow rate at a 35 Degrees C temperature rise is a high flow rate of 20.30 litres/min DHW output, or at a 40 Degrees C rise then its 17.5 litres/min flow rate, which is still a high flow rate even in the deepest of the worst winter conditions, which many properties will never endure. The temperature is easily changed with our intuitive menu structure in the in-built control panel.

Central heating system side of the boiler

Central heating output rating: based on flow and return temperatures of 80/60 and the fact that current new build homes have radiators that have an average of 1.5 kw output. Our 50kW gas combi boiler has the capacity to generate 53.85 kW of central heating output power, sufficient to heat up to 35 radiators on the system, effectively serving as commercial heating. Please note that if you are retrofitting, the total number of radiators cannot exceed the boiler’s central heating output rating of 53.85 kW.

Some of our competitors claim a 50 kW combi, but in reality, the heating side of the boiler has only 35 kW of output.

There are not many companies producing a gas fired 50 kW combination boiler. Some people may regard a boiler produced by the Worcester Bosch company, namely the Worcester greenstar 8000 50kw combi boiler range, as a direct competitor to our boiler, but in reality, this boiler and all the information we can find, will only produce:

Central heating output (kW): 33.8 kW at 80/60 °C or 50/30 °C condensing mode: 35.7 kW

While our gas boiler will produce 49.19 kW of heating power at 80/60 °C or at 50/30°C in condensing mode it will produce 53.85 kW at maximum capacity.

Thus, can you really call the worcester bosch greenstar 8000 a 50 kW combi?? You make the final decision, but it seems a bit short to us?

Domestic hot water performance (DHW) –

The Worcester greenstar 8000 is 48.9 kW rated on the dhw side, the output is –

DHW output at the hot tap (35°C temperature rise) – 20.3 l/min hot water flow

DHW output at the hot tap (40°C temperature rise) – 18 l/min hot water flow

With a plus or minus of 15%  quoted ?? umm 

Whilst our boiler will produce the following outputs for domestic hot water

DHW output at the hot tap (35°C temperature rise) – 20  l/min hot water flow

DHW output at the hot tap  (40°C temperature rise) – 17.5 l/min hot water flow

There’s no plus or minus 15% for our data – we will produce those figures quoted above

and this should be more than adequate for more than one bathroom.

Domestic hot water performance of the combi

Main features – Due to its excellent domestic hot water flow rate, with a temperature rise of 30 degrees C @ 23.40 ltrs/min of hot water flow or with a temperature rise of 35 degrees C @ 20 litres /min of hot water, this 50kW combi gas boiler is ideal for a two-bathroom house. Our next size down our 34kW combi boiler will do 16 litres /min just to compare the performance.

Hot water cylinder

As no domestic hot water cylinder is used with a combination boiler, unlike system boilers, you are lowering your carbon footprint and energy fuel consumption for your domestic hot water usage, as gas is only consumed in this ERP A rated efficient combi boiler when hot water is required – it’s one of the key features – your only heating hot water when you require it – which results in lower energy bills / gas bills.

Should your cold mains not have enough flow rate to adequately provide for your hot water needs then a system boiler, which uses a separate hot water cylinder for storing water for larger volume applications or heat only gas boiler (also are also called a conventional, regular boiler or traditional boiler), then please see our webpage here – 50kW Boiler which can be used in a multi boiler cascade system for even larger outputs.

Heat exchanger style / construction

This powerful wall hung boiler is equipped with a stainless-steel exchanger with a large Ø 28mm monotube coils, which not only benefits from very low pressure drops, but guarantees lower risk of clogging, with greater thermal efficiency, and greater ease of cleaning with lower running costs. We guarantee or warranty period the heating water heat exchanger for 10 years, when a good quality magnetic dirt and air separator is fitted to the heating system, and the boiler is serviced annually.

Technical data of our combi boiler – 50kW

 

50kw gas combi – central heating output / hydronic heating – ErP  “A” energy efficiency rating – energy savings trust approved with high energy efficiency.

 

50kw combination boiler central heating and domestic hot water technical data

Energy efficient domestic hot water “A rated” ErP energy efficiency rating  – DHW flow rate at various temperature rises 

 

combi boiler 50kw domestic hot water flow rate at various temperature rises

mains gas and propane gas and electrical requirements for the combination boiler

inc vat; increased power; intuitive menu structure; customers; fantastic new design;company

Download the 50kW Combi Boiler Manual Flexiheat UK

Boiler Flue Options / Spares

We do various flue options / accessories, the most common is a co-axial, which takes the combustion air from outside, and the combustion gases from the device to the outside – making these combi units room sealed when used.

The most common flue kit is our horizontal co-axial kit – both of these can be used up to 10 metres in length

Horizontal flue kit from flexiheat UK;worcester greenstar 8000;ex vat;worcester bosch;ex vat;worcester bosch;ex vat;inc vat;quietest boilers;inc vat;ex vat

Horizontal kit from Flexiheat UK

 

Or the vertical option

Vertical flue kit from Flexiheat UK;ex vat;worcester bosch;worcester greenstar 8000;ex vat;worcester bosch;ex vat;worcester bosch

Vertical kit from Flexiheat UK

 

Both of these accessories can be used up to 10 metres maximum vertical flue length, losing 0.8 metres off the length for every 90° elbow used, and 0.5 metres for every 45° elbow used from the overall maximum vertical flue distance.

Or by using a split system, we can achieve routes of up to 60 metres of maximum vertical flue length.

boiler Split flue pipe system;

Split pipe system from Flexiheat UK

Boiler controls

With an easy-to-use display with an intuitive menu structure and greater connectivity with any Opentherm compatible controller, our 50kw combination boiler is made to suit your lifestyle, as well as your home.

One of the new features of OpenTherm – (which is a standard communication system that connects natural gas, lpg gas, oil or even electric boilers with room thermostats). This means that your combi boiler can be used with any OpenTherm compatible thermostats or controllers – the best-known brand on the UK market to date is between Nest or Hive which are , but we also provide a solution from stock, which has extended range, and key features such as the ability to control your boiler from a mobile phone, pad or your computer with wireless connectivity.

This means if your away on from home, you can have controllers that will activate your energy efficient 50kw combi gas boiler based on your postcode location in relation to your property – so it’s nice and warm when you get in or should you be travelling, you can adjust the boiler start time in relation to when your due home on your phone or other device, should you be delayed for any reason you simply adjust the time on your device.

Class 5 modulating controls, can provide an increase of 3% system energy efficiency, as they have a direct impact on the efficiency of the modulating combi boiler, by modulating the flow temperature in line with the internal temperature of the property.

Easy Remote

Advanced class 5 remote control (full colour display), which performs the dual function of a thermostat and remote control of the boiler. This controller must be wired from its location to the gas boiler.

Easy remote controller from Flexiheat UK; Class 5 modulating boiler or water heater controller that is wired.

Easy remote controller – Wired – from Flexiheat UK

  • Daily / weekly heating and hot water programming;
  • Heating and hot water temperature setting;
  • Reset by remote control in the presence of resettable fault codes – rapid diagnosis
  • Thermoregulation management for reduced running cost of the heating system
  • Appliance parameter programming (technician level)

 

Cloud Warm WIFI (Wireless) Controller

A free-standing class 5 advanced remote control (full colour display) thanks to the free downloadable app which performs the dual function of chrono thermostat and remote control of the device from a mobile phone or tablet.

Cloud Warm Wired controller from Flexiheat UK; stock;delivery;stock;website;inc vat;stock;delivery;stock;worcester greenstar 8000;ex vat

Cloud Warm Wired controller from Flexiheat UK

 

  • Daily / weekly heating and DHW programming;
  • Cloud warm application available for free on the Apple Store and Google Play; No annual charges to pay
  • Heating and DHW temperature setting;
  • Push notifications to a mobile device in the presence of any abnormality or fault;
  • Reset from a mobile device in the presence of resettable fault codes;
  • Thermoregulation management for reduced running cost.

Cloud Warm WIFI (Wired)

As above functions, but this unit must be wired back to the 50kw gas boiler

Stock;delivery;ex vat;worcester bosch; inc vat;worcester bosch;ex vat;inc vat; ex vat;inc vat;ex vat; ex vat;inc vat;ex vat;inc vat;ex vat;inc vat

Cloud Warm Wireless Opentherm controller from Flexiheat UK

 

 

Brand and Quality manufacturing

With its modern design, with A rated ErP efficiency for heating and DHW (energy savings trust approved) this combi gas boiler with design led product aesthetics , and all installer touchpoints for ease of installation is well suited to larger homes.

Our 50kw combi boiler for larger homes is manufactured in accordance with ISO 9001 and ISO 1400 certified management systems and testing techniques. Should you require more information, best deal, free boiler quotes or delivery times, then please contact our sales teams for the best 50kw gas combi boiler in natural gas or LPG on the UK and Irish market. You can call our office on 01202 822221 or send an email via our contact form.

Whole house electric tankless water heater UK

Whole house electric tankless water heater UK

 

Whole house electric tankless water heater UK from Flexiheat UK

Whole house electric tankless water heaters from Flexiheat UK an alternative or replacement for tank-type water heaters

A whole house electric tankless water heater has become highly desirable in the UK due to its ability to provide unlimited domestic hot water instantly, without any waiting time or the need for water storage. Instantaneous water heaters have a compact design and can be easily installed in tight spaces, such as a kitchen cupboard or something similar.

While the statements above are correct, it is important to recognise some limitations, such as the limit on the number of outlets that can be used simultaneously with instant hot water heaters, the need for close proximity to hot water outlets, and the need for a three-phase electric supply to power a whole home’s energy-efficient tankless water heater.

Key Point

  1. You require a 3 phase power supply to have a viable whole house electric tankless water heater in the UK

Energy efficient water heating

With rising energy prices, many homeowners in the UK are looking for ways to cut energy costs and make their homes more energy efficient. One way to do this is by installing an electric tankless water heater, also known as an instantaneous water heater or demand-type water heater, is one way to do this. Tankless water heaters provide domestic hot water instantly, as needed, eliminating the need to constantly heat and reheat a tank of water like traditional tank-type water heaters. This can lead to significant energy savings, making whole house electric tankless water heaters an attractive option for eco-conscious homeowners.

How do tankless water heaters work?

Tankless water heaters work differently than traditional water heaters that use a storage tank. When you turn on a hot water tap, cold water travels into the tankless unit. Inside the unit, an electric element heats the water instantaneously before sending it to the tap or shower. The unit directly heats the water without storing it, ensuring you never run out of hot water. Even when hot water isn’t in use, traditional water heaters with storage tanks must constantly reheat and maintain water temperature, resulting in energy waste.

Benefits of whole house electric instant water heaters

There are several key benefits that make whole house electric tankless water heaters a smart choice in UK homes:

Energy efficient hot water

Instantaneous water heaters only heat water when needed, rather than maintaining a whole tank of water at temperature constantly. This results in major energy savings compared to traditional water heaters. Homeowners can save 20% to 60% on water heating costs.

Continuous domestic hot water

Instantaneous water heaters provide an unlimited supply of hot water on demand. You’ll never run out of hot water for showers, washing dishes, doing laundry, and more. The water heater activates when hot water is needed and shuts off when not in use.

Space Savings

Instantaneous water heaters are compact and mount on a wall, freeing up floor space that standard storage hot water cylinders water heaters use. This makes them a great choice for smaller homes or properties, such as flats, etc.

Long Lasting

Tankless heaters last up to 20 years, twice as long as traditional storage hot water cylinders. The lack of a water storage tank increases their lifespan as you heat water on demand

Environmentally Friendly

The energy efficiency of tankless heaters means lower carbon emissions. Less electricity is required for water heating.

Safety

With no hot water storage tank that standard water heaters have, there is less risk of leaks or rusting. Tankless water heaters are safer, provide more reliable hot water, are easier to install, and are space saving.

Factors to consider when choosing an entire house tankless unit

If you’re considering switching to a whole house tankless water heater, there are a few important factors to take into account:

Power Rating: The correct power rating ensures that your tankless unit can handle your household’s hot water demand. Look for a power rating of 18–27 kW for a whole house appliance or even 36kW depending on your demands.

Flow Rate: The water flow rate, measured in litres per minute (LPM), must meet your household’s peak hot water needs. The electric water heater appliance’s power ratings directly influence the heated water flow rate’s capacity or output.

A standard shower head has a hot water demand of 7 or 8 litres a minute

Standard shower head 7 to 8 litres a minute flow rate

Standard shower head 7 to 8 litres a minute flow rate

Please be aware drench showers – can have some huge flow rates from 15 litres to pretty much any flow rate – 30 litres per minute is not uncommon.

Drench showers with hot water flow rates from 15 to 30 litres a minute

Kitchen sink taps – 4 to 6 litres per minute

Sink taps – 4 litres per minute – standard type.

Basin / cloakroom “spray taps” – 2 litres per minute – these water saving spray taps, are very popular now, as they save water and energy requirements.

Bath mixer taps – modern bath taps have an approximate demand rate of 12 Litres per minute.

So be adding all your potential hot water outlets demand, then applying a diversity factor (a factor that not all the hot water outlets will be used at the same time) you can calculate your hot water demand.

Energy Source: Electric tankless heaters often make the most sense for UK homes. Make sure your electric system can handle the power demands.

Size: Choose the appropriate size tankless heater for your home’s water heating demands, number of bathrooms, etc. An undersized unit won’t meet your hot water needs.

Location: Pick an appropriate indoor location with adequate space and accessibility.

Efficiency Rating: Look for a high energy efficiency rating to maximise savings.

Product range

 

Our electric tankless hot water heaters have four power ratings, or output ranges, in “one” tankless water heater unit. Except for the 27kW and 36kW electric instantaneous water heaters, which feature a single power setting.

For example, our 9kW to 15kW electric instant water heater allows consumers to pick power ratings of 9kW, 11kW, 12kW, or 15kW in one model, while our 17kW to 24kW instant water heater may be adjusted to 17kW, 18kW, 21kW, or 24kW output.

The cold water mains temperature at the deepest winter times is typically 10 degrees Celsius, thus an average temperature rise of 30 degrees Celsius is necessary to provide hot water for usage in the winter months. The data below shows the performance at a temperature rise or Δt = 30

 

Power output of the tankless water heaters9kW to 15kW instantaneous water heater17kW to 24kW instantaneous water heater27kW instantaneous water heater36kw instantaneous water heater
Energy efficiency classAAAA
Heat capacity ( power setting options)9/11/12/15 kW17/18/21/24 kW27 kW36 kW
Power supply – All require a 3 Phase power supply 400V 3N~400V 3N~400V 3N~400V 3N~
Mains water supply pressure (Bar) min – maximum1 to 101 to 101 to 101 to 6
Hot water flow rate at  Δt=30 in litres per minute4.3/5.2/5.8/7.28.1/8.7/10.1/11.61317.3
Rated current (Amps)3 x 13/15.9/17.3/21.73 x 24.6/26/30.3/34.63 x 393 x 52
Dimensions – W x D x H (in mm)245 x 126 x 440245 x 126 x 440245 x 126 x 440315 x 140 x 492

Please note that this range of compact instantaneous water heaters requires a minimum flow of 2.5 litres per minute to start heating the water. If the flow rate is lower than this point, they will not operate.

Our 9kW to 27kW instantaneous water heaters feature a LCD display showing the tankless water heaters set temperature

Digital display on our instantaneous electric water heaters from 9kw to 27kW from Flexiheat UK

The digital display on 9kw to 27kW , showing the hot water temperature set on the water heater

and our 36kW tankless water heater has a traditional temperature dial and look like this

36kW electric instant water heater from Flexiheat UK

36 kW Electric instant water heater

Benefits of Going Tankless for Whole House Water Heating

Switching to a whole house electric tankless water heater provides a range of benefits:

  • Save significantly on energy costs by only heating water on demand
  • Enjoy hot water with an unlimited supply of continuous hot water for all your needs
  • Free up extra space by eliminating a storage electric water heater
  • Reduce your home’s environmental impact with an energy efficient system
  • Enjoy convenience, reliability, and safety with an electric on demand hot water tankless unit
  • Get a long-lasting water heater that will serve your property for many years

By going tankless for your whole house, you can gain energy savings, unlimited hot water, extra space, and peace of mind knowing you have an eco-friendly, highly efficient water heating solution meeting your household’s needs.

Installing Your New Tankless Water Heater

Once you select the right electric tankless water heater model for your home, hire a qualified plumber for installation. Proper installation is key to maximising efficiency and providing hot water performance. Key steps include:

  • Select an appropriate indoor location that allows access to the instant hot water heater; they are a very compact design, so this shouldn’t be an issue.
  • Make any necessary electrical upgrades to handle the instant hot water heater requirements.
  • Electricity supply: ensure you have properly sized electric cables and breakers.
  • Connect the water supply pipes with components such as isolating valves and a filter on the cold water feed to the water heater.
  • Insulate water pipes to limit heat loss to sinks or the shower.
  • With a tankless water heater tailored to your specific home set-up, you’ll get the right choice with superior function without wasting energy and benefiting from energy savings for years to come.

Going tankless is the smart choice

With rising energy prices, whole house electric tankless water heaters make increasing sense for eco-friendly UK homeowners looking to save on costs. By only heating water on demand, tankless heaters provide endless hot water while being much more energy efficient than traditional storage tank heaters. Choosing the right size unit with professional installation provides a long-lasting, highly effective hot water solution with no standby energy losses and reduced energy consumption. Going tankless can make your UK home more sustainable while cutting your energy bills. It’s the smart choice to enjoy reliable heated water whenever you need it.

So if you require a price, check stock or to purchase one of electric water heaters for entire home hot water needs please contact us on 01202 822221 or use the email contact form .

Electric tankless water heater range 9kW to 36kW

Electric tankless water heater range – 9kW to 36kW output

 

Electric tankless water heater range from 9kW to 36kW for on-demand water heating via electrical power - Flexiheat UK

3 phase tankless water heaters from Flexiheat UK

 

Our Electric tankless water heater range are 100% energy efficient instantaneous water heaters, that provide domestic hot water in a cost effective manner as they heat water only on demand without wasting energy.

Being an electric water heater, they require a three phase electrical supply as you require the Amps to provide hot water at an adequate flow rate for a bath, shower or multiple hot water taps such as kitchen sink taps or bathroom sinks taps in properties or commercial buildings.

Key takeaways

  • The main disadvantage of electric tankless water heaters is that the electrical power ratings set a limit on the hot water flow rate output achievable.
  • This is why generally you require a Three phase electrical supply rather than a single phase electrical supply to power the instant water heater units.
  • Single phase electric can’t supply the Amps (power) required for an electric instantaneous water heater
  • Heating water by providing hot water on demand lowers energy consumption and lower price energy bills for your water heating system.

Tankless water heater electric powered advantages

When opposed to conventional tank-based water heaters, tankless water heaters—also referred to as an on-demand water heater, instant water heaters or instantaneous water heaters or an inline electric water heater—have a number of advantages. Here are a few of the principal benefits:

1. Energy efficiency: The electric element heats only heat water when there is a demand, unlike storage tank-type water heaters that continuously heat and reheat stored water. This on-demand instant hot water heating process can save a significant amount of energy, reducing water heating energy costs by 20-30%.Electric instantaneous water heaters are 100% energy efficient

2. Space-saving: Tankless water heaters are much more compact in size compared to bulky storage hot water tank heaters and are easier to install. This makes them ideal for homes, smaller homes or apartments with limited space, as they can be mounted on a wall or installed in cupboards.

3.No pressure and temperature safety valves or hot water expansion vessels are required to be installed as there’s no hot water storage in the instant water heater appliance – Thus you don’t have to comply with the “G3” unvented water heater regulations that we have in the UK for hot water installation.

3. Unlimited hot water supply / endless hot water: If the capacity of a standard electric storage tank water heater is surpassed, you can run out of hot water if the tank’s capacity is exceeded .In contrast, instantaneous water heaters have an infinite supply of hot water—so long as the demand doesn’t exceed the instant water heaters flow rate capacity.

4. No standby energy losses: Storage tank water heaters constantly lose heat through the tank walls, even when no hot water is being used. Instant hot water heaters eliminate this standby heat loss, further contributing to energy savings and reduce energy bills for your domestic water heating.

5. Lower risk of leaks and floods: Since instant water heaters don’t store large volumes of hot water, they have a lower risk of leaks and flooding compared to electric storage tank hot water heater models, which can cause water damage if they fail.

Electric tankless water heaters, with their energy savings and longer lifespan, can make them a cost-effective option in the long run, especially for businesses or households with high hot water demand or require a unlimited supply of heated water and in areas with high energy costs due to their 100% energy efficiency.

Instantaneous water heaters range

Our electric tankless hot water heaters have four power ratings, or output ranges, in “one” tankless heater unit. Except for the 27kW and 36kW electric instant water heaters which only have one power setting .

I.e. Our 9kW to 15kW electric instant water heater allows users to select power ratings of 9kW, 11kW, 12kW, or 15kW in one model and our 17kW to 24kW instant water heater can be set to 17kW,18kW,21kW or 24kW.

The cold water at the deepest of winter periods is normally 10C in temperature , thus the standard temperature rise of 30 °C is required to provide hot water for use in the winter period. This is shown as Δt=30 in the data below. So you can select the right model for your requirements.

 

Power output of the tankless water heaters9kW to 15kW Output ratings17kW to 24kW Output ratings27kW36kw
Energy efficiency classAAAA
Heat capacity ( power output setting options)9/11/12/15 kW17/18/21/24 kW27 kW36 kW
Power supply – All require a 3 Phase power supply 400V 3N~400V 3N~400V 3N~400V 3N~
Mains water supply pressure (Bar) min – maximum1 to 101 to 101 to 101 to 6
Hot water flow rate at  Δt=30 in litres per minute4.3/5.2/5.8/7.28.1/8.7/10.1/11.61317.3
Rated current (Amps)3 x 13/15.9/17.3/21.73 x 24.6/26/30.3/34.63 x 393 x 52
Dimensions – W x D x H (in mm)245 x 126 x 440245 x 126 x 440245 x 126 x 440315 x 140 x 492

Please note that this range of compact instantaneous water heaters require a minimum flow rate of 2.5 litres per minute to start heating the water. They will not operate if the flow rate is lower than this point.

Our 11kW to 27kW instantaneous water heater models feature a LCD display showing the instant water heaters set temperature 

Digital display on our instantaneous electric water heaters from 9kw to 27kW from Flexiheat UK

The display on our hot water heater from 9kW to 27kW , showing the hot water temperature set on the water heater

 

These range of instant hot water electric heaters use bare wire heating elements in the heat exchanger which are particularly well-suited for use in hard water areas

 

Our 36kW instantaneous water heater has a traditional temperature dial and look like this –

36kW electric instant water heater from Flexiheat UK

36 kW Electric tankless water heaters with no standby energy losses

Our 36kw tankless water heater uses copper shielded heating elements within a heat exchanger, this dependable technology ensures long lifespan of operation and resistance to air bubbles and water deterioration.

These electric water heaters can provide enough hot water for commercial applications

Full manuals are here for these instant water heaters 

EIWH5 Series Electric instant water heaters manual from 9kw to 27kW – Flexiheat UK

EIWH36 – 36kW Electric instant water heater manual – Flexiheat UK

Instant Water Heater

Whether the instant water heater is supplying fixtures such as shower, bath, sinks or multiple taps, our electrically powered units heat water ‘instantly’ as it flows through the appliance.

They can be installed either as inline electric water heater or in series to provide enough hot water to suit all installation requirements.

Energy efficient Hot Water heating

Being 100% energy efficient, our 3 phase tankless water heater range have accurate temperature control of water flows you can rely on for daily use in business or domestic water heating applications without storage tanks. You get endless hot water for your hot water tap or shower with reduced energy bills.

Contact us

Should you require further assistance, check stock, or get a price on the best electric tankless water heater  product range on the UK market which are 100% energy efficient, then please don’t hesitate to contact our sales team on 01202 822221 or click here for our email contact form.

Condensing water heaters

Condensing water heaters

Condensing water heaters with high efficiency domestic hot water heating with storage or condensing tankless water heater options from Flexiheat UK

 

Condensing water heaters have become the norm since Part L of the UK building regulations came into force in June 2022.

The more stringent water heater requirements of the Part L building regulations apply to both newly built and existing non-domestic building stock.

This basically eliminates the option to swap out existing non-condensing water heaters with the same type of water heater. Any replacement hot water heaters must utilise condensing technology within the domestic hot water heater to produce savings on both a monetary and emission level i.e., carbon emissions, as a condensing water heater will deliver cutting edge efficiencies.

A low emission level hot water system helps the UK achieve our drive to a lower carbon economy and ErP compliant condensing water heaters help this.

However, in the rare event that the Building Control authority determines that replacing a non condensing gas fired water heater water is not suitable or feasible in non domestic buildings, a minimum seasonal efficiency of 80% for natural gas or 79% for LPG may be utilised.

But there are very few circumstances in which you can’t use a condensing water heater, to be fair, so these exceptions would literally be “once in a blue moon,” as they say, if at all.

The energy efficiency benefits of condensing water heaters now mean that the residential hot water systems market has also rapidly moved to this type of water heater’s installation, as they deliver cutting edge efficiencies and produce savings on your water heating bills.

As of yet, there are no regulatory requirements to use a gas fired condensing water heater in a domestic property, but the economic benefits of using less gas to produce domestic hot water for a home or flat through higher efficiency alone have driven the domestic market this way.

However, the commercial hot water regulations or the commercial water heaters market often lead with regards to regulations, and the domestic market then follows, so we can envisage that condensing water heaters will soon be mandatory in this sector before long.

Energy efficient water heating

Condensing gas fired water heaters have a hot water efficiency level of up to 105%. Which is essentially an extra 12 to 15% more performance than an older gas fired non condensing water heater.

A second heat exchanger in a condensing water heater preheats the incoming cold water by using waste heat from the exhaust gases. This process lowers the exhaust gas temperature, boosts energy efficiency, and increases the hot water flow rates of the water heaters.

A cooler exhaust allows for additional possibilities for flueing materials, such as polypropylene plastic flues. Condensing gas fired water heaters need to dispose of the acidic condensation water through a drain and possibly a pH neutralizer because water vapour condenses inside the appliance when the exhaust gas cools, and this is acidic in nature.

Gas fired water heaters

We have a large, high efficiency gas fired condensing water heater range that are direct fired water heaters for small or high hot water demand that can be required in commercial or industrial hot water heating applications such as hotels, leisure centres, and hospitals.

Wall hung water heaters

SFC or SFK gas fired condensing water heater range from Flexiheat UK

SFC or SFK Condensing water heaters range – in natural gas or LPG

 

Our wall hung condensing water heaters range consists of three models a 28kW, 34 kW or 50 kW output water heaters.

These water heaters benefit from various flueing options: horizontal or vertical flue systems, room sealed or conventional flued with various flue terminal options for easy installation.

The two smallest water heaters come with the option of a pump for a domestic hot water recirculation system (designated the SFK model) or without a pump (our SFC version) for straight through water heating, which are the most common appliances we sell. The larger 50kW model comes with a pump as standard, which is capable of being turned off for straight through direct water heating.

With a large 28mm single-pipe coil heat exchanger made of stainless steel, the “SFC” or “SFK” condensing water heater range benefits from very low pressure drops, less chance of blockage, increased thermal efficiency and easier cleaning and delivers high volumes of temperature accurate hot water. Other safety features such as protection to IPX5D rating are standard.

There is no water storage within these units, so there is no heat loss compared to a storage water heating system.

This is the basic rule: the higher the kW output, the higher the DHW flow rate performance

When heating cold water to a certain temperature, this is known as the temperature rise or Delta T (shown as Δt in the charts below). The normal bathing or showering water temperature is 38°C to 40°C, depending on personal preference.

For winter performance

We recommend sizing the water heater on a Delta T of 30 degrees C, shown as “Δt 30” for the majority of the UK, in Scotland, we recommend using “Δt 35”.

During the summer period

You can use “Δt 20” as the temperature rise.

SFK or SFC 28kW Gas fired condensing tankless water heater

 

Water Temperature RiseΔt 20Δt 25Δt 30Δt 35Δt 40Δt 50Δt 60Δt 75Flow rates
SFK / SFC 2820.6616.5313.7811.8110.338.276.895.51Litres/minute
1239.89991.91826.59708.51619.94495.96413.30330.64Litres/hour

 

Download the SFC 28kW Gas condensing water heater with no pump manual

Or with pump for hot water recirculation systems

Download the SFK 28kW Condensing water heater with pump manual 

 

SFK or SFC 34kW Gas fired condensing tankless water heater

 

Water Temperature RiseΔt 20Δt 25Δt 30Δt 35Δt 40Δt 50Δt 60Δt 75Flow rates
SFK / SFC 3425.0920.0716.7314.3412.5510.048.366.69Litres/minute
1505.401204.461003.72860.33752.79602.23501.60401.40Litres/hour

 

Download the SFC 34kW Gas condensing water heater manual with no pump manual

Or with pump for hot water recirculation systems

Download the SFK  34kW Condensing water heater with pump manual 

SFK 50kW Gas fired condensing tankless water heater

 

Water Temperature RiseΔt 20Δt 25Δt 30Δt 35Δt 40Δt 50Δt 60Δt 75Flow rate
SFK5036.9029.5224.6021.0918.4514.7612.309.84Litres/minute
2,2141,7711,4761,2651,107886738590Litres/hour

Download the SFK  50kW Condensing water heater with pump manual 

Please be aware that the highest temperature that the water temperature can be set to is 60 degrees Celsius on the standard water heaters ; on request, we can, however, build a higher temperature unit that can reach up to 85 degrees Celsius. These water heaters are frequently used for the pasteurisation process in the dairy and farming industries, as well as in other applications that call for high-temperature washdowns and water for process applications.

For high demand hot water heating that commercial applications can require, these high efficiency commercial water heaters can be used in cascade for example- we go into more depth on the of this type installation here – Commercial gas water heaters

These on demand high efficiency gas water heaters have various essential safety features, and can be used to top up heat-pump water heaters, which can struggle to achieve the desired water temperatures.

Control options

You can set the water temperature on the control panel of the water heater; however, should you wish the facility to change the water temperature, then we have a remote controller that you can site in your kitchen to boost the water temperature to 50 °C for dishwashing, which is the recommended temperature for removing grease from cooking utensils and dishes.

Easy remote controller from Flexiheat UK; Class 5 modulating boiler or water heater controller that is wired.

Easy remote controller – Wired – for our condensing water heaters from Flexiheat UK

 

Storage options

We also supply three condensing storage tank water heaters options – which are available as either LPG or natural gas fired water heater and are all ErP compliant water heaters.

We do a 50kW water heater option with a 330-liter storage cylinder

A picture of a gas hot water tank or gas fired hot water cylinder from Flexiheat UK, which are used for water heating in large domestic, commercial, and industrial applications. These units are condensing gas water heaters.

Gas water heaters with storage systems for high volumes at intermittent times demand. These ErP compliant condensing water heaters are energy efficient and cost effective to run.

 

A 34kW water heater option with a 150 Litre stainless steel storage cylinder

gas hot water tank or gas fired hot water cylinder from Flexiheat UK

or a 28kW water heater option with a 150 Litre stainless steel storage cylinder

internal picture of our hot water heater with storage tank which is gas fired from Flexiheat UK

SFKA 28 or 34 KW Output models – Natural gas or LPG powered

We go into more depth on these storage condensing water heaters that are often used in commercial buildings here – Condensing gas hot water tanks or cylinders

Where are condensing water heaters used?

Everywhere, from residential and smaller business settings such as homes, cafes, hair salons, bed and breakfasts establishments to industrial and large commercial applications such as sports complexes, hospitals, colleges, or schools, we have a complete range of high-efficiency water heaters for every warm water heating requirement.

Contact us

Should you require anymore assistance, information, check stock or get a price / cost on our effective (both in a monetary and emission level) condensing water heaters range please contact our customer services sales team on 01202 822221 or use our email contact above on the web page.