Domestic hot water storage tank or vessel

With regards to a domestic hot water storage tank or vessel , first we have to define what domestic hot water is in relation to a storage hot water tank or hot water cylinder.

They are a hot water storage tank / hot water storage vessel / hot water accumulator tank or thermal store dhw tank to provide hot water for commercial buildings or process applications that have a requirement for large peak demands of sanitary grade warm water for multiple bathrooms in hotels etc or a process application.

Domestic hot water

Domestic hot water is the heated potable water that feeds taps, showers, baths, or the kitchen hot taps. It is also referred to as sanitary hot water. The hot water is heated up from the cold water mains temperature to the recommended temperature for storing hot water of at least 60 degrees C.

The cold water enters or that feeds the hot water tanks can either be mains water supply at mains water pressure or via a cold water storage tank/cold water tank – (often called a header tank) that is used on a vented hot water cylinder.

It is then heated up by an external heat source such as an energy efficient water heater , which can use various heat sources such as gas, oil,heat pump or an electric heating system to heat water directly. This hot water is then stored in a hot water storage tank, which is designed to retain heat as a thermal storage tank for use when there is a demand for the hot water, which is often a large load, in a short period of time.

They essentially serve as water reservoirs, and they’ll be connected to either an indirect or direct fired hot water system to increase hot water storage volumes to accommodate high demand applications with thermal storage in hot water cylinders.

A hot water storage tank or hot water storage vessel is also known as a hot water buffer tank because it “buffers” hot water loads during peak hot water demand.

Hot water storage tanks

A hot water storage tank or vessel, just like its counter parts, such as indirect cylinders or heating products, must also be energy efficient water cylinders and must carry an ErP energy efficiency rating for standby heat loss.

Any hot water storage systems must comply with the Eco-design ErP Directive.

On September 26, 2017, restrictions on hot water storage tanks’ standing heat losses (heat lost to the surroundings equals wasted energy) were implemented to ensure maximum efficiency.

Storage tanks, or cylinders with a capacity of 2,000 litres or less must meet a minimum energy performance standard in order to be sold legally in the UK and the EU. The same applies for a thermal store.

The rate of heat loss determines the energy rating of a hot water storage tank , which is measured in watts. The insulation of the hot water tank is crucial to achieving a high efficiency band since each efficiency band has a minimum and maximum heat loss proportional to capacity. The best hot water tanks have a thick layer of high-performance polyurethane foam to cover the gap between the tank and the cover.

As part of the energy labelling directive, which says that all energy-related products, like home appliances, must show their efficiency rating in a clear way, hot water storage tanks with a capacity of 500 litres or less must also have energy labels.

Our entire hot water storage tank line complies with both ErP and the energy labelling directive and can be fitted with additional electric immersion heaters or a single immersion heater as additional heat sources to top up or as a backup heating system to the primary water heating system.

hot water cylinder

Is it a hot water cylinder, a thermal store, a hot water tank,hot water holding tank or a buffer tank?

Ultimately, they are just a storage tank for hot water—you can call them what you want.

In simple terms, they are hot water storage tanks heated by other heat sources designed to store hot water for peak hot water demands or loads, normally for domestic use hot water or a process water heating system such as warm washing down systems demand etc.

They are not an indirect hot water cylinder heating system that uses a boiler (normally condensing boilers) or solar panels to heat the surrounding water in the hot water cylinder via a heat exchanger coil within the storage tank or hot water cylinder. Thus the term an indirect cylinder.

Hot water tank range

We do various types of cylinder or tank, these being – a glass lined hot water tank ( vitreous enamelled ) or stainless steel in construction-

Vitreous enamelled DHW / glass lined hot water tanks

Vitreous enamelling is an impermeable, food-safe coating that looks like porcelain and protects the metal surface of a storage tank when it comes in contact with water.

Vitreous enamel, commonly known as porcelain enamel, is a material created by burning powdered glass onto a substrate at temperatures ranging from 750 to 850 °C. The powder melts, flows, and hardens to form a smooth, long-lasting vitreous covering, thus these units are also known as glass lined hot water storage tanks.

In addition to the test temperature required by current standards (22 degrees C), our vitreous enamel has a food grade certification at 120 degrees C. This makes sure that it is of the highest quality, even at high operating temperatures.

The maximum operating temperature of an enamelled storage tank

Because of their capacity for molecular interaction with the steel surface, these hot water storage tanks can withstand a maximum DHW storage heated water temperature of 95 degrees C without deterioration or detachment.

Pressure rating and warranty period

These warm water storage tanks, are 8 Bar pressure rated and come with a 5-year warranty

200 to 1500 Litre Warm Water Storage Tanks – CV-R range

Dimensional detail of our hot water storage tanks – The “R” range have a inspection / clean out port which is 146mm in diameter as standard – item “J” on the drawing – we can also fit an immersion heater in this port as well.

Rigid, mould-injected PU thermal insulation that has demountable sections that allow you to get the 800 and 1000 litre hot water cylinders through a standard 800mm doorway.

Demountable thermal insulation on the 800 and 1000 Litre

The full range can be seen on the following brochure –  Please see page 10 for units from 200 to 1,500 Litres , and page 36 for 1,500 to 6,000 Litres of storage cylinder capacity.

Download the Vitreous Enamelled DHW storage tanks or vessels brochure

Commercial hot water storage tanks

We do a full range of commercial hot water storage tanks or industrial hot water tanks all the way up to 6,000 litres

These large-capacity commercial and industrial hot water storage tanks have both side and top DN 400mm manholes to access the interior of these large hot water storage tanks for inspection, cleaning, and maintenance tasks.

Thermally insulated with rigid, mould-injected, 80 mm-thick, polyurethane foam, with an insulating piece in the same material on the DN400mm side manhole.

As standard our storage hot water cylinders are fitted with a cathodic protection system by sacrificial anodes with a charge meter , the anodes must be checked periodically for wear and replaced if necessary.

The anode charge metre is a straightforward and convenient method for determining the state of the anode. Check whether the dial indicator is in the green zone (anode with sufficient charge) or the red zone (anode with insufficient charge, requiring replacement of the anode).

As an option on our industrial hot water storage tanks, Correx permanent anode (cathodic) protection units can be included, which are special titanium anodes that emit the necessary current for the metal surface to be protected via an automatic potentiostat connected to the main power supply.

Maintenance free: since the cathodic protection system is permanent, unlike sacrificial anodes, there is no degradation, and no replacement of the anodes is necessary.

1,500 to 6000 litres commercial or industrial hot water storage vessels, tanks or cylinders

Dimensional detail of our commercial hot water storage tank range

stainless steel hot water storage tank

Stainless steel hot water tanks have become an increasingly popular type of domestic hot water storage tank as they have many benefits.

• Stainless steel hot water storage tanks do not require a sacrificial anode for normal potable water conditions  , unlike an enamelled or glass-lined hot water tank or hot water cylinders. However there is an exception:

  Aggressive agents such as >150 mg/L chlorides in the water with storage temperatures of >75 ºC – in these circumstances cathodic protection is required.

• This means that the inspection and maintenance regime of a stainless steel hot water tank is less than that of enamelled hot water cylinders.

• Stainless steel storage tanks or hot water cylinders used to have a working pressure advantage over enamelled storage tank versions, but these days the hot water tanks are equal in the pressure rating.

Dimensional detail of our stainless steel domestic hot water storage tanks

For example our 500 litre hot water storage tank in stainless steel – is 770mm in diameter and has a height of 1690mm

Our range of stainless steel domestic hot water storage tanks are detailed more in the following brochure

Stainless steel hot water storage tank brochure

Insulation of the DHW storage tanks

The insulation keeps the temperature of the DHW storage at a constant level for extended periods of time without requiring extra energy input. It is an over-sized, rigid, mould-injected PU thermal insulation. This results in fewer external energy source start-ups (such as tankless water heaters), which reduces energy usage, which directly translates into actual energy cost savings when using an insulated hot water storage tank.

Hot water system

A vented cylinder must feature a vent pipe that allows the water to expand as it warms up in the storage tank and safely condenses any residual warm water into the cold tank. To maintain water pressure to the vented cylinders, there must be “head” or distance above the tank or vessel, which is why the stored cold water tank is often located in the attic space in UK homes for vented cylinders.

On the other hand, unvented cylinders, or buffer tanks, are a sealed domestic hot water heating system. The expansion of the domestic hot water as it heats up is taken up by an expansion vessel in an unvented cylinder or unvented cylinders.

Should you require any more support, selection advice or costs/ get a quote on our domestic hot water storage tank range , with fast delivery times then please use the contact us form page on the website, or feel free to give us a call on 01202 822221.

Gas Water Heaters

Gas Water Heaters

A gas water heater or gas fired water heater is used to produce domestic hot water for your domestic properties e.g. flat, house or commercial property. This hot water is of sanitary quality and is used to feed showers, baths, and hot water taps or faucets. They can be mains gas (natural gas) or LPG gas fired.

Water heater gas fired

One of the many benefits of a gas water heater is the energy delivery that it can dissipate into the water and thus the good flow rates they can achieve when compared to instantaneous electric water heaters, which require a lot of Amps for heating water and normally a three-phase electric supply to achieve similar flow rates.

Gas fired water heaters

Our entire range of our gas water heaters can be powered by either mains gas (also known as natural gas) or LPG (propane gas), which is your liquid gas. It is easy to convert our high energy efficiency gas fired water heaters from one type of gas to another via a simple-to-fit gas conversion kit.

Hot Water Heaters

Gas fired water heaters can be split into two main categories:

On demand water heaters

On-demand, tankless water heaters or instantaneous water heaters will use less energy than storage water heaters and are the most energy-efficient method for heating water, with high performance mains pressure to all warm water outlets. However, the instant hot water flow rate demand and the usage of the hot water outlets by the customer installation must be considered to ensure they’ll work correctly. These gas water heaters are low NOx and cost effective and available in natural gas or LPG. We go into more depth on this range here – instantaneous gas water heater

Storage hot water heaters

Alternatively, we do a range of low NOx storage gas water heaters, which are condensing water heaters with high energy efficiency; the two stock units have a water storage quantity of 150 litres, which is ideal for customers with a larger demand for domestic hot water, such as having a periodic requirement for high volumes of water in a short period of time or intermittent times, that an instant hot water heater couldn’t service with its flow rates. You simply need to store water / storage systems for certain customers’ requirements in the most cost effective manner.

Storage option – 28kW or 34KW output options

The “SFKA” range, as they are designated, is available in natural mains gas or as LPG as their fuel source and is available with an output of either 28kW or alternatively a 34kw output model.

They come complete with a 150 litre stainless steel storage tank, which has a long warranty, and all the associated plumbing pipework and a pump local within the casing.

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

They also have easy access for service or to maintain this reliable water heater unit as the panels are removable-with loads of room to get at and checkout the plumbing components that connect the heat exchanger of the gas water heater to the storage tank. These gas water heaters are sometimes referred to as a gas hot water tank or cylinder, and are detailed on this webpage – gas hot water tank or cylinder  in full detail.

Thermal efficiency

In any domestic or commercial hot water heating system, any gas fired water heaters used these days must not only be a reliable appliance but also as efficient as possible.

This is where condensing water heaters come in as a solution with regards to gas fired water heaters, as you can recover the latent heat from the heater’s flue gases and recover that energy via a heat exchanger back into the hot water temperature-and not lost to the flue gases and the environment whilst saving the customer money.

Gas fired water heaters – Because the flue gases leaving the water heater are cool, they form a visible mist or plume of water vapour whilst leaving the flue terminal point or location

Because of this condensing process, our condensing gas water heater range are at least 15% to 20% more efficient than non-condensing systems. With the current high cost of energy, any customer may save significantly on their water heating costs by the installation of a water heater that will condense, whether in a domestic or commercial application.

Thermal efficiency or energy efficient ErP rating – “A”

This type of water heater is ErP “A” rated-and due to recent legislation changes, you must now fit condensing gas fired water heaters in all new and retrofit commercial water heating systems. Please visit this location on our site for more in-depth information on this- Water heater legislation changes-Part L Building Regulations-June 2022

Gas water heater controls

You can use the thermostat built into the control panel on the gas water heater to set the hot water temperature output required, or alternatively, we do a remote temperature controller option too.

If you require any more suitable support, solution advice, check stock, delivery times or require a price on our gas water heaters from Flexiheat UK, then please use the contact us form page on the website, or alternatively feel free to give us a call on 01202 822221, as we sell direct to the trade and public customer base. Connect with us on Facebook or Twitter so you can contact us at any time.

Commercial Boilers

Gas condensing boilers for commercial boiler installations

Commercial boilers are manufactured to fulfil the special needs of commercial premises or businesses or for heating apartment buildings with heat interface units, via a local heating network. Commercial boilers work similarly to domestic boilers, but they generate a larger heat output, making them suitable for commercial boiler installations.

Whether you are a professional heating engineer or a business owner looking to upgrade your boiler, this introduction about boilers with high energy-efficiency for commercial or even industrial heating will show you your options.

Our commercial boiler range has been designed and developed to meet a wide range of applications and project requirements from heating commercial stores, factories, schools, hotels, pubs, and leisure industry – just to name a few commercial heating applications with condensing technology to achieve the energy savings.

Commercial boiler systems

They are ideal boilers or perfect solution for producing domestic hot water as well as doing the heating system in a commercial property. This is achieved by using a boiler or even boilers in conjunction with suitable indirect hot water heaters or heat interface units. Making them a system boiler in this case.

Wall hung boilers

Gas boilers – wall hung boilers with condensing technology for commercial heating

Wall hung gas condensing boilers are the most popular units these days for commercial buildings – especially in reference to commercial gas boilers, as they are the ideal boilers to fit in relatively small boiler houses and are easy to cascade to suit any project.

Commercial gas boilers in cascade offer higher modulation ratios, and when you bear in mind that commercial boilers spend 70% of their time at 30% of heat output, and the other 30% of their time at full output range, commercial gas boilers that have a high modulation ratio support these demand cycles.

The result is longer run times with lower cycle rates as the boiler controller operates the required number of commercial boilers or boiler to meet the heating demand of the system, which also reduces the wear and tear on boiler installation as continually cycling on and off can result in early failure of gas valves, fans and pumps fitted to the boiler or heating system.

We supply a full range of high efficiency commercial gas boilers, with modulation figures for single piece boilers of 1:20 and when used in cascade, with a maximum kW output of 960kW, so we can cover or fill any industrial or industry heating requirement as well as commercial applications.

Commercial floor standing boilers are still a very popular installation in the UK, floor mounted boilers are available as gas fired either natural gas or as an LPG condensing boiler , electric or oil fired condensing boiler ranges with some very large outputs.

Commercial floor standing boilers

Commercial floor standing boilers or free standing boilers are still a very popular installation in the UK for commercial applications, floor standing boilers are available as gas fired either natural gas or LPG, electric or oil-fired ranges with some very large outputs. There are various subject options –

Gas-fired floor mounted boiler range

Gas condensing commercial and industrial range – stainless steel heat exchangers

Our gas fired floor mounted commercial gas boiler range is detailed more on the following webpages – Commercial gas boilers – floor standing, or wall hung up to 960kW of output power or our commercial and industrial gas fired floor mounted boilers – which you can install up to 12,160 kW of heating power – which is a large amount of heat ! and enough to cover any installation requirements from one of the leading brands of gas condensing boilers for industry or commercial applications.

Oil fired floor standing commercial / industrial heating boilers

Also available as a dual fuel commercial boiler – oil and gas fired

Commercial oil fired boilers, that are floor standing start at 70kW and go all the way up to 1,550 kW in condensing oil fired boilers – the UK and European legislation states that all boilers from 70kW to 400kW must be condensing to meet the Energy Related Products Directive requirements for heating systems for commercial premises. See this webpage for more information on our commercial floor mounted oil boiler range.

But it would be foolish not to use condensing technology above the stipulated 400kW, as condensing condensing technology is 20% more efficient than a non-condensing boiler, and benefit from low emissions. Again, they can produce domestic hot water through our commercial hot water indirect cylinders or heat interface units.

Frequently asked questions

Here’s some frequent questions we get

What are commercial boilers?

Commercial boilers are widely used to heat structures such as offices, schools, blocks of flats, and local surgeries or hospitals etc. They typically create hot water using either gas, electricity, or oil as a fuel source. This heated water is used to power the heat emitters in the building, such as underfloor heating, radiators, or fan coil units.

What size is a commercial boiler?

Gas and oil-fired commercial boiler range in size from 70kW to 2,000 kW plus. This wide range of output capacities helps to guarantee that businesses may select products that fit their individual heating and hot water requirements.

Commercial boiler prices UK

If you require any further support, advice, latest offers of our commercial boilers range, be they floor standing or wall hung models then, please contact us via our email contact form above on the website or call our business sales services team direct on 01202 822221 and deal with your commercial project interest. Sign up and follow us on Facebook and twitter for our latest news.

15kW Electric Boiler for a wet central heating system – radiators or underfloor heating.

15kw electric system boiler

Our 15kW electric boiler is our most popular electric boiler, for central heating and hot water system replacement for a gas boiler or oil boiler, as customers look to reduce their carbon footprint / carbon emissions. They can be used for underfloor heating or traditional radiator central heating, or even a combination of both.

These are electric system boilers, so have a pump, pressure relief valve and expansion vessel fitted internally, and these eliminate unnecessary external plumbing and pipework and have a 100% electric energy efficiency.

They can also be used to produce domestic hot water, when used in conjunction with an indirect hot water cylinder, especially if the property has a bath, as you will need an element of domestic hot water storage, as an electric combi boiler will not be able to cope with the demand.

Central heating with green electricity

With gas boilers being phased out in the UK to reduce our reliance on fossil fuels and reduce carbon emissions, electric boilers when powered by carbon neutral or renewable energy sources are just one of the solutions to reducing global warming and help replace gas boilers.

Largest electric boiler on single phase supply?

A 15kw electric boiler is the largest electric boiler you can run off a single phase supply that is commonly connected to properties with a 100 Amp electric supply that we have in the UK.

Thus, at maximum output these 15kw electric boilers can consume 72 Amps – when wired to a single phase / 240-volt supply

Should you put a kettle, a toaster, tumble drier, or hair dryer on, which all can consume 13 Amps each of your single phase / 240 Volt electricity supply – then you can get very close to maximum amps available or even blow you main board fuse.

With the following unique product – Our maximum current Watcher – which essentially, temporarily reduces the boilers output, and thus the amps drawn, should the boiler get close to your maximum amps – all automatically – when the amps drop, the boiler automatically goes back to the power required.

The” maximum current watcher” – it is basically a releasing relay (restriction of current). The relay monitors and controls the electric voltage in the whole house or flat and in the case of exceeding the permitted values of the electric current it reduces the input power to the electric boiler. All of this is done automatically, without any human intervention needed. This system will not only operate on our 240 volt / 1 Phase Electric boilers, but also our 400 Volt / 3 phase units as well. This now means that you can use our 15kW electric boiler model, in a property or flat with standard 240-volt, single phase with no worries or problems that the boiler will trip out the main electric board.

Electric Boilers

Electric boilers work without emitting any fumes or waste gases that you get with a gas boiler, which reduces your carbon footprint, eliminates the possibility of a carbon monoxide leak, and allows for flexible installation because a flue system is not required . Electric boilers are almost completely silent when running too thanks to the silent triac power switches. We supply a full range of outputs up to 45kW, so if you require another size, please see our webpage – electric heating boilers 

Wall mounted heating boiler

Advantages at a glance:

Energy saving circulating pump

High efficiency erp smart pumps are used in our 15kw electric boilers, with stainless steel impellers.

Pump protection against clogging

Regular spinning of the pump (once every 24 hours) prevents potential clogging of the pump during an extended electric boiler off period

Very quiet operation

Thanks to the silent triac power switches in this electric heating boiler – they are completely silent.

• Smart electronic modulating system with step less regulation in low power steps or jumps of 2.5 kW each – the modulating electronic control of this wall mounted heating boiler, will ramp up and down the power steps or levels , to suit the central heating system requirements – be it underfloor heating or radiators – this auto heating regulation mode or process ensures reduced energy consumption, as the electric boiler matches the heating output to the demand of the hot water radiators or under floor heating, and result in lower energy bills / running costs.

• Automatic modulating electric boilers (sem system)  – the minimum power of the electric boiler is 2.5 kW, then the boiler modulates up and down the output range in 2.5kW steps .You also have the capabilities of setting the boiler at a maximum kW output i.e., to either 2.5, 5, 7.5, 10, 12.5 or 15kW, and the boiler will ramp up and down depending on the heating system demand to the maximum set value.

• Comes with a wall bracket steel template for wall mounting these electric heating boilers.

Download the Flexiheat Electric Boiler Range Brochure

Thermostats

• Possibility of connecting a controller with “OpenTherm +” communication – these are your “Nest” or “Siri” type of thermostats, that can be wireless or internet thermostats- that you can control from an app on your phone, iPad or computer. Allowing you to control your central heating system.

Or you can use traditional ambient thermostats,

• Possibility of regulation according to the room or outside temperature

• Possibility of remote control of the electric boiler using an SMS message in conjunction with an SMS module (optional extra)

• Digital control panel with a clear, two-digit LED digital display

• Safety switch protection with heating flow detector

• We use copper elements – not stainless steel shielded elements – as copper has a shorter heat up period, and thus is a better product in this application.

• HDO communication – remote switching of the operation to a low rate by the electricity supplier- very handy if you’re on an economy 7 type of cheaper tariff scheme – saving costs on running your

• Internal heating expansion vessel

• Possibility to control the outlet temperature of the electric boilers by means of a 0 – 10 Volt electric signal

• Possibility of producing hot water in an external storage tank after installing a three-way valve which is controlled by the electric boiler.

• Top design – with all the components to operate a wet central heating system be it underfloor heating systems or radiators, with all pipework connections easily accessed at the bottom of the boiler, for ease of installation. The auto air vent is located at the top of the boiler, to ensure it gets the air removed from these electric boilers and an easy to use digital display inbuilt to the unit.

• Smaller external dimensions of the packaged boiler, with lower water content

• Integrated refill (regulated by hydro block) integrated frost protection

• Small dimensions – you have more location’s to fit you electric heating boiler, with a time saver install, with no additional external plumbing and pipe work are required , as these are sealed system boilers.

• Auto air vent – to remove any air from the electric boilers heat up chamber, and to prevent any damage to the immersion heater / heaters.

• Two year warranty for our insulated steel manufactured boilers.

• No noxious fumes or gases when you use electric central heating boilers.

Electric combi boiler

They simply don’t work at this size , you need a three phase supply for these boilers to give a usable hot water flow rate. See our dedicated webpage on electric combination boilers for more info.

Hot water indirect cylinder heating

1. The electric boilers have an automatic system in them that operates both the heating and the indirect DHW cylinder

2. It operates in switching mode

3. Domestic Hot Water always has priority

4. For heating it works at the “heating” temperature – lower temperature (25C to .80°C), can be set and controlled – and you can use weather compensated control –

Compensated weather control- the boiler automatically drops the flow temperature relative to the weather conditions – for example on a day when the temperature is 12C outside – and you want 20C inside, the boiler works out that you only require 50C to the radiators, and this saves you energy and thus running costs.

The boiler then automatically switches on the pump and immersion heater heating elements and regulates to the desired temperature for the heating system.

5. For the DHW cylinder, the electrical boiler heats up to a higher temperature (usually 75-80°C, to heat the DHW indirect stainless steel cylinder as quickly as possible)  – the automatic control closes the heating circuit and opens the DHW storage heater heating circuit, switches on the pump and heating elements and heats to a higher temperature (75-80°C) and heats the DHW cylinder very quickly (100 litres in approx. 10 – 20 minutes! Based on a 15kW )

6. After the DHW Cylinder is heated, it switches to heating (see “4.”)

Why is this indirect set up important?

Because you can have two required temperatures – i.e., the heating side of the boiler, may be running underfloor heating – which needs a maximum temperature of 45C, or if the boiler is compensating the flow temperatures to a radiator system, for example – it may have reduced the flow temperature to 50 or 60C – This would not be a high enough temperature to heat the indirect hot water cylinder

And this is the problem with the old “S” and “Y” plan control system, that use 2 x 2 port valves – one for the heating and one for the DHW indirect water cylinder. You can only have one temperature coming out of the electric boiler – which may well be not high enough to supply the domestic hot water cylinder.

Electric central heating boilers

So call us at Flexiheat UK as we are the electric boiler specialists for the United Kingdom , our helpful friendly and professional sales team are ready to deal with your enquiry, get a price or order please contact our sales team on 01202 822221 or click above on our website for our email contact form.

Electric Boiler 9kw Output

A 9kw electric boiler works just like a gas boiler, just that it’s powered by electricity rather than gas. They benefit from easier installation, as no requirements for flue offers flexible installation location – you can decide where to locate your electric boiler to suit your needs or your customer requirements, unlike a gas system which can be dictated by the flue system requirements of gas or oil boilers.

With no annual gas safety certificate required for electric boilers resulting in lower maintenance costs, and being suitable to installed in customers property for either a retrofit or new installation.

Wet central heating with an electric boiler

These 9kW electric boilers, which provide wet central heating come complete with an integrated “ERP” energy efficient compliant heating pump and an integrated 7 litre expansion vessel, making these electric boilers what is commonly known as a “sealed system boiler” or sealed systems.

A compact and small electric boiler – energy efficient home heating electric solution from Flexiheat UK

This means this electric boiler can not only do the heating system, be it an underfloor heating or radiator heating system, but can also heat an indirect cylinder for your domestic hot water requirements if so required.

This allows you to have a “sealed heating system,” meaning that no feed and expansion water tank (i.e., open vented systems) is required in the loft — which can be prone to freezing or bursting, you don’t get this potential problem with sealed systems. It also makes installation much easier and more compact in the property because all the necessary parts are inside the electric boiler casing, such as the factory fitted circulating pump and expansion vessel.

Electric boilers

• Factory fitted circulating pump – Energy saving ErP compliant pump – quality products
• Heated water temperature output range of up to 80 Degrees C operating temperature
• Power surges are avoided with soft start and zero volt switching.
• 9 stage heating – this electric boiler 9kw output will ramp up and down to the heating demands in small 1Kw steps or stages – closely matching the requirements of the system and thus reducing electricity consumption
• Electric system boiler outputs all the way from 1kW to 9kW for a wet central heating system, i.e. underfloor heating or standard radiators and domestic hot water purposes via an indirect cylinder
• No moving parts for long life soft start operation
• This electric boiler is virtually silent in operation.
• Fitted with an auto air vent to eliminate air from the heating system
• Space saving unit – this electric boiler is small in size but will deliver a lot of heat – will fit in a standard domestic airing cupboard
• No Requirement for annual safety certificate for landlords and no fuel tanks required -reducing maintenance costs
• Can be controlled via the nice touch screen panel – with operation front control panel indication of temperature, times etc
• The boiler can be installed for heating only, or for heating and domestic hot water production, via an indirect hot water storage cylinder
• Can be used with standard radiators or underfloor heating systems – efficient wet central heating
• This boiler can use a standard room thermostat ( which must be volt free) , or a “Opentherm” suitable/ compatible room thermostat such as your Hive or Nest type of thermostats, which can allow you to control the electric boiler status via an phone app, iPad or computer and reduce electricity consumption and running costs with weather optimization and compensation that Opentherm intelligent controllers do.
• Constructed with top brand quality engineered products from the leading manufacturers which ensures long life of the electric boiler
• No flue system is required for an electric boiler – a nice convenience to have, as it cuts down installation time for the installer and costs for the customer – flexible installation location – annual safety certificate
• Has the ability for automatic switching to off peak tariffs
• Product code – FHEL9 – Single phase electric system boiler ( can all be run on a 3 phase supply to)

Energy efficient wet central heating system

To ensure maximum efficiency from our unit, our 9kW electric boiler incorporates nine-stage heating modulation, with small increments of 1kW power steps. This unique benefit will modulate the boiler to reduce electricity consumption and running costs, via better heat load matching of the central heating system as the thermostatic radiator valves open and close or in the case of underfloor heating systems control.

These boilers can be wired either by a 3 Phase 400 Volt electric or 1 Phase 240 Volt electric mains electrical connection- we have highlighted the single phase boiler electrical details in the above data – as it’s the most common electric supply to this boiler size.

The full brochure for our range of units available can be downloaded here –

Flexiheat Brochure For Electric Boiler Range 

Energy efficient domestic hot water heating via a hot water cylinder

Delivery or production of domestic hot water is achieved via pressurised or open vented indirect cylinder, for fast filling baths and to supply multiple tap outlets with hot water supply at the same time – schematically like so

The boilers have an automatic system within that operates both the heating and the indirect DHW cylinder

It operates in a switching mode and Domestic Hot Water always has priority

Lower temperatures ( from 25C to 80°C ), can be set and controlled for the heating circuit– and you can use Equithermal control – as our unit is “Opentherm” compatible with various controllers or via our operation front panel indication.

Equithermal control is compensated weather control- the boiler automatically drops the flow temperature relative to the weather conditions – for example on a day when the temperature is 12C outside – and you want 20C inside, the boiler works out that you only require 50C water temperature output to the radiators, and this saves you energy and thus running costs. – more on this in this video

Why is this set up important?

Because you can have two required temperatures – i.e., the heating side of the boiler, may be running underfloor heating – which needs a maximum temperature of 45C, or if the boiler is compensating the flow temperatures to a radiator system, for example – it may have reduced the flow temperature to 50 or 60C – This would not be a high enough temperature to heat the indirect hot water cylinder

For the DHW cylinder, the electric boiler heats up to a higher temperature (usually 75-80°C, to heat the DHW cylinder as quickly as possible) -the automatic control closes the heating circuit and opens the DHW heating circuit, switches on the pump and heating elements and heats to a higher temperature (75-80°C) which heats the DHW cylinder very quickly (100 litres in approx. 10 – 20 minutes! Based on a 15kW)

If you use an unvented mains cold water supply hot water storage cylinder, then you can have a powerful hot water supply delivering mains pressure showering hot water and fast filling baths.

Note – If you require a 9kW electric combi boiler or combination boiler, look at our solution – as a true 9kW electric combi won’t work correctly to produce an adequate flow rate based on the water temperatures we get in the UK and Ireland especially in the winter period – the flow rates as just pathetic and unusable – look our solution here – electric combination boilers

Open vented systems

Pressurised or open vented central heating systems? open vented systems are now old technology when it comes to a wet central heating.

You can use our boilers on an open heating system, but the require minimum head is 8 metres,

But we don’t recommend it as open vented system allow oxygen ingress into the heating water, which result in corrosion in the system, with standard radiators and some thermostatic radiator valves being manufactured in steel this is not a good idea.

Electric boiler with 9kw Output electric powered

We at Flexiheat UK limited, supply and stock a large range of electric boilers, with our 9kW electric boiler being the best on the UK and Irish markets. Having many benefits such as the best boiler modulation or turndown ratio on the market. Being extremely compact and suitable for use in a house, apartment, mobile home, or flat, along with other types of residential properties. With soft start and zero volt switching to avoid power surges.

Please don’t hesitate to contact our sales customer services team on 01202 822221 or use our email contact form via the contact tab above to message us and get the best price. We normally have stock of the electric boiler unit on the shelf, or we can arrange a delivery on a small pallet service, which can either delivered on an overnight delivery service or a 2/3-day delivery service depending on the customer requirement. All our customer invoices are inc vat, as we are vat registered company number GB236 9061 01.