Heat Pumps work by extracting energy from one source and transferring it into another system. This energy can be extracted from the, the, from or almost any medium that is capable of absorbing energy from the sun. The simplest way to think about them is to look at your fridge. You probably haven’t noticed but Fridges have a heat exchanger on the back, which gets hot when your fridge is trying to cool down (incidentally that why they work much more efficiently if you have an air gap behind and why free standing ones work better than under the counter type). Heat pumps work like a fridge in reverse. Trying to ‘cool’ the ground outside (or the air or the lake) they have to reject heat somewhere like the radiator on the back of the Fridge, if that radiator was in your house it would heat it up. Like a fridge the harder they have to cool they more heat they have to reject to the radiator. This is why ground heat source pumps are more efficient than air heat source pump or water because there is a bigger temperature difference. And the deeper you can bury the tubes the more heat they generate as the ground gets warmer the deeper you go (it’s like a very weak version of geothermal energy). Ground source heat pumps are more efficient than air source but they need considerable land area. They also need the pipes to be buried and the appliances themselves are physically bigger and subsequently require more indoor space as well. Water source are a specialized version of the two where you submerge the coils in a lake or river. They are less efficient than ground source but easier to install obviously, depending on how close your water ‘source’ is. Like any energy generation system the better insulated your house is the less you need to heat it and this especially true of heat pumps. If you install a heat pump in a house with poor insulation and normal radiators your heat pump will be less efficient and potentially cost you a lot of money to run as it will require additional mains back up power equivalent to heating your house with an immersion heater! While we are talking about energy usage a crucial difference of heat pumps, as opposed to most other renewable energy systems is that they need an independent energy supply (electricity) to run their compressor pump.
Not all heat pumps work well with traditional existing wet central heating systems and will need to consider extra investment in new oversize radiators. They actually work best with under floor heating and thus typically take 12 to 24 hours to make any significant temperature change.
As you can appreciate they really need careful consideration so give us a call for advice.