A thermal store holds excess heat, normally produced by a renewable heating technology (solar thermal, heat pumps or biomass), to be used to heat your space and/ or water, at times when it is required.
These technologies may produce too much heat or produce heat when it is not required, and so by using a thermal store you can maximise the efficiency of these systems.
In doing so you can use less heat on demand created by fossil fuels and save money on your energy bills
- Thermal stores are very well insulated hot water cylinders (sometimes called buffers or tanks) that lock in heat for a long period. The thermal store will be coupled with a renewable energy technology, or several, storing the surplus heat produced from these.
- When required, mains water passes through a heat exchanger in the thermal store, which transfers heat from the thermal store water to the mains water, to then be used.
- In some cases, there may also be an electrical heating element, such as an immersion heater, acting as back up heating for the thermal store
Thermal stores may hold energy from more than one technology and may provide heat for space only, for water only, or heat both. In fact, to get the most out of a thermal store, it should be used to manage multiple inputs and outputs
A thermal store can be sited almost anywhere in a property (as long as the header tank is higher than the heating systems (radiator or underfloor heating).
Thermal stores coupled with a biomass boiler or a biomass stove with a back boiler work well as biomass systems work better when used to their maximum output. Log boilers in particular are designed to burn logs in full loads, rather than in small quantities throughout the day.
The size of a thermal store connected to a biomass system will depend on the fuel type, pellets, wood chips or logs. A pellet boiler or stove will require a smaller thermal store, a log boiler will require a larger one.
Thermal stores coupled with solar thermal systems can mean the heat produced by the renewable energy system can be used to heat space, as well as water. However, a solar thermal system with a thermal store would not be eligible for the Domestic Renewable Heat Incentive.
Thermal stores coupled with heat pumps can help prevent heat pumps short cycling (cycling on and off when heat demand is low and occasional). This can reduce running costs and maintain the life span of the heat pump.
Thermal stores can also be connected to a conventional boiler, for exampleeg an aga with a boiler, or other electrical heating elements like an immersion heater.
Thermals stores require virtually no maintenance.
The cost of a thermal store depends on the size of the cylinder required, the heat exchanger type, and how many connections you need. The costs can range from under a thousand – £4,000.