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