Heat Pumps
Heat pumps can obtain usable heat from either the ground or the air and transfer this heat into water. They have been extremely popular in the Nordic countries for many years but are now being installed throughout the whole of the world.
At one metres depth the average soil temperature in the UK is between 10 and 13 degrees. By use of glycol filled pipes buried in the ground the heat is taken from the ground and transferred into the heat pump where by means of heat exchangers and a compressor temperatures up to 65 degrees can be obtained. This is why heat pumps are effective. Heat pumps have efficiencies of between 300% and 400%. They are able to convert 1 kWh of electricity into 3 - 4 kWh of heat.
They cost roughly two to three times as much as a conventional boiler but, given the right property, can reduce annual running costs by as much as 70%. The main reason heat pumps are a cost effective way of heating your home is by converting a unit of electricity into 3 to 4 units of heat. HOWEVER, it is critical that the building being heated is as thermally efficient as possible otherwise efficiencies can fall to as low as 1 to 2 i.e. 1 unit of electricity will only produce 2 units of heat. This will lead to high annual electricity bills and even possibly will cost more than oil or gas to run. Do not forget that electricity is expensive to buy (currently up to 17p/kWh) and oil at 50 pence a litre costs approximately 4.8 p/kWh. So electricity is currently 3.49 times more expensive than oil so installing a heat pump in a thermally inefficient house with a heating system designed for water at 70 degrees might cost you more to run than oil or gas.
for Heat Pumps
This having been said they are very efficient at producing water at 35 degrees which is what most under floor heating systems run at. So if you have under floor heating, are doing a major refurbishment or building a new property heat pumps have a lot to offer. They require minimal maintenance, you don't need a tank and so it will never run out. As a guide for working out how much land is required for the trenches you will require approximately ten meters of trench for every kW that the heat pump is sized at i.e. an 11 kW heat pump (which will happily heat a 140 sq meter property) you will need 10 times 11 i.e. 110 meters of trench.
Here at The Energy Warehouse we have an 11kW air source heat pump which heats our building (which is newly built and very thermally efficient) very effectively. It costs approx £800 a year to run compared to an oil boiler which would cost £1400 a year to run. Is it noisy? No! Come and have a listen...
If you are interested in seeing if your house is suitable for a heat pump please contact us.