General Questions

To understand how heat pumps work it is easier to think of two separate circuits. The collecting circuit and the heating circuit, one collects the heat and the other circuit gives it out.
  • Flow
  • Return

Ground source heat pumps save you money they run on clean electricity and a correctly designed installation will provide your heating and hot water for less than with oil or gas. The high efficiency of a ground source heat pump also means a significant saving on carbon emissions, a heat pump will produce much less CO2e than an ordinary boiler because it uses less energy to create the heat.

A ground source heat pump will save money on your fuel bills, how much money you will save depends on what fuel you are currently using and how well the system is designed. The efficiency of the system changes as the temperature of the collected (incoming) heat changes and the temperature of the heat output changes.

A ground source heat pump runs best with a source temperature above 4˚ and an output temperature less than or equal to 35˚C. At these sort of temperatures it is able to provide up to 6 kWh of heat for one kWh of electricity which means the savings can be significant running a ground source heat pump.

  • Save Money
  • Cut CO2
  • Annoy the energy companies with your cheaper bills!
By collecting a large amount of low grade heat from the ground and concentrating it into a smaller amount of high grade heat the heat pump can supply the heat you need. The water in the ground loop is pumped into the heat pump, the heat pump takes a small amount of heat from it and so the water coming out of the heat pump is about three degrees cooler. This goes back into the underground pipes where it gets warmed up again. The heat taken from the ground loop is concentrated inside the heat pump and used to heat up the water flowing around the radiators or under floor heating pipes and to heat the hot water tank.

With a ground source heat pump the heat is absorbed in the collecting circuit from the water in the ground loop each time it goes through the heat pump. The heat taken from the water during its passage through the heat pump is replaced by absorption from the ground surrounding the pipes. This ground in turn is warmed up again by transferring heat from the area all around and below. This heat originally comes from the warmth of the sun, to get any significant heat from the centre of the earth the pipes would have to go much deeper in the ground. A ground source heat pump is still often referred to as a geothermal heat pump.

The Nottingham Partnership regularly publishes comparison prices for different fuels and in December 2014 the cost of electricity used for heating was 3.46 times as much as gas, 2.97 as much as heating oil and 2.3 times as much as LPG (bottled gas) so a heating system running at an efficiency of 600% would be just over half the price of gas, just under half the price of heating oil and just over a third of the price of LPG.
If the installation has been designed to incorporate weather compensation the temperature of the water in the radiators also changes throughout the season and this can give better efficiencies than using a fixed output temperature. If the system is designed to produce enough heat with a flow temperature of 35˚C in the radiators when it is say -2˚C outside then when it is warmer outside the radiators don’t have to be so hot and the flow temperature can be reduced. Weather compensation changes the flow temperature automatically which makes the heat pump operate more efficiently and save money.

Other Questions

YES! a lot of people say you cant, or that you are better off to continue with a regular boiler. They are wrong, fitting a heat pump to an exsisting building as opposed to a new build is no problem at all.

The trouble with pricing these things is its difficult to get a decent average cost, I can say clearly its not cheap. Dont let that put you off because the government renewable heat incentive is aimed at subsidising the extra cost of having this stuff installed! if you take a house using 30,000 kWh of heat over a year the RHI payment for a ground source heat pump would be £4328.50 per year for seven years (plus inflation if there is any). This gives a total of £30,299. During the 7 years and thereafter you will be making a saving of around 50% on your heating bills – our heating is costing 2.3p per kilowatt – cheaper than gas or oil or any other fuel. This payment would cover the cost of the drilling, the heat pump and probably a replacement hot water cylinder (we need a special high efficiency coil inside). The efficiency of the system depends on the temperature we need to run it at to give you the temperature you need in the house so we would probably need to upgrade the radiators. So you can see its difficult to price it up, if you have had an EPC done recently just let us have your postcode and house number and I can give you a better “ball park” figure.

  • Higher cost to install, but RHI will pay this back
  • Greater space needed to make trenches but boreholes could counter this
  • 50% cheaper heating bills for life.
vaillant ground source heat pump
Ground source is cheaper to run, more expensive to install but the renewable heat cashback is 18.8 pence per kilowatt. Air source is cheaper to buy but more expensive to run with 7.7 pence per kilowatt cash back. air source heat pumps advantages and disadvantages - Air source is cheaper to buy and simpler to install but a little more expensive to run with 7.7 pence cash back from the Renewable Heat Incentive for each kilowatt hour of heat produce less the electricity used .Ground source is more expensive to install but cheaper to run and the renewable heat cashback is 18.8 pence per kilowatt hour of heat produced. The Renewable Heat Incentive lasts for seven years from acceptance into the scheme.
COP
So that you can compare the efficiency of different heat pumps, the manufacturers state the energy performance of their heat pumps at fixed temperatures for the input (source) temperature and the output (flow) temperature. Test are carried out in controlled conditions to EU standards to make sure the products can be fairly ranked. For ground source heat pumps this is usually at a source temperature of 0˚C and an output temperature of 35˚C this is shown as B0/W35 which stands for Brine 0˚C water 35˚C, the water in the under ground pipes is described as Brine as it contains Antifreeze to stop it freezing inside the heat pump where temperatures can get pretty low. The amount of heat produced is divided by the amount of electricity used to produce the heat and the answer is called the Coefficient of Performance and is abbreviated to COP.
SPF
The COP figure is only valid at the temperatures quoted; it’s a snapshot of the performance. During the course of the heating season the temperature of the water in the ground loop slowly decreases, it starts off at say 10˚C at the start of the season and ends up at say 1˚C or 2˚C at the end of the season. These changes in temperature affect the efficiency of the system and the results of these changes are expressed as the Seasonal Performance Factor which is abbreviated to SPF. The SPF is an estimate of the average COP over the course of the season.

Contact

Who we are

Heat Collector are here to help you with the design, installation and maintenance of ground source & air source heat pump systems

  • Design
  • Installation
  • Maintenance
  • MCS accredited
  • RHI assistance

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