Coefficient
of Performance COP = Heat into building / Electrical power consumption
= 3How
does it work?
The evaporating gas
passing through the expansion valve and takes the heat from the ground
at the evaporator. Then the compressor turns this gas into liquid which
releases its heat into the house at the condensor.
A large amount of pipe is required in the ground outside to to absorb
heat from the cold ground and consequently drops the ground temperature
around the pipe by one or two degrees. Then a relatively small amount
of water is heated to 35 degrees C in the house when the gas is compressed
to liguid by the compressor at the condenser. the heated water is stored
into a cylinder which becomes the water heat source in the building.
1- Heat pumps use electricity to drive compressor and the water pumps. Electricity is a an expensive fuel in the UK. This is because it is mostly generated from oil, gas or coal.
2- COP of 3.5 is required to break even on electricity fuel costs compared to gas central heating.
3- A large piece of land, a lake, a pond or a well is required to generate enough heat for a heat pump.
4- The capital cost of heat pumps, including outside ground equipment installation, is high.
5- They require sophisticated controls such as weather compensation to keep water temperature down and to keep running cost low.
6- They work at their best efficiency at low temperature and are therefore best suited with low water temperature underfloor heating systems. Such as the Pexatherm UFH systems.
Please visit Energy Saving Trust for more information.