Heat pumps are a renewable technology that converts energy in the ground, water or air into heat. This process delivers green, low-cost, energy-saving heating and hot water all year round.
Heat pumps work a bit like a fridge, but in reverse. The heat pump uses a cool source – could be air, water or the ground; it circulates water around the source and collects what heat there is; this is then put through a condenser which uses small amounts of electricity to concentrate the temperature of the water. In efficiency terms this can result in 1 unit of electricity being used to generate up to 3 or 4 units of heat. The heat that it will generate is limited to 30-40oC depending on the temperature of the source.
The equipment is quite bulky, looking like a large storage heater. Sometimes (such as for air source heat pumps) this is attached to an external wall and can be heard in the same way as air conditioning. Ground source heat pumps collect the heat from the soil. This can be done either by digging up a trench in the lawn running to around 50 metres in which is laid a plastic pipe; or if there is little space, it can be done vertically with a drill rig (which is quite a bit more expensive).
A ground source heat pump could cost from £11-15,000 and air source from £7-14,000; saving depends on many variables such as what your current and future fuels are and what you power with your heat pump. There may be Feed In Tariffs in the form of the Renewable Heat Incentive that you can claim, which will be based on your rated generation. Current rates are 18.8 and 7.3 pence per kWh though these change regularly.
These are technologies to be used with care because:
- There have been many complaints about the efficiency of the systems that have been installed. Installers need to be very experienced and you need to be sure that this sort of (not really renewable technology) will work for you.
- Heat pumps are most successfully installed connected to underfloor heating. This can work because the water temperatures needed for that are low and because it probably only worth installing HPs if you are doing other work at the same time.
- The heat pump works best in a well-insulated property, as it is providing low-temperature heat. It is usually on 24/7 and runs off ordinary electricity tariffs, not economy 7, so there are extra electricity costs to offset the savings in other fuels.
If you’ve installed a heat pump, we’d love to hear about your experiences – both good and bad. Please get in touch!