FAQs Archive

Q: How Does a Ground Source Heat Pump Work?

A ground source heat pump, also known as a shallow geothermal heat pump, works by absorbing heat from the ground and transferring the heat into buildings as hot water. The heat pump works on the same principles as a domestic fridge. In your fridge a heat pump extracts heat from the inside and transfers it to a small radiator at the back, where the heat is dissipated into the room. In exactly the same way a ground source heat pump takes heat from the ground and transfers the heat into the building by circulating hot water though radiators, or underfloor heating pipes. A heat pump works by increasing the temperature of a fluid it contains at the temperature of the ground using a cycle of compression and evaporation of a thermal transfer fluid fluid. When a large volume of gas is compressed into a small space the heat energy in the gas becomes concentrated, causing the gas to heat up. When the gas is then depressurised, and turns back into a liquid, energy is released. A heat pump uses a heat exchanger to capture the released energy and transfers the heat as hot water into the heating circuit of the building and hot water supply system. Once the highly pressurised gas has condensed, and released its heat, it then becomes very cold. The heat pump uses a heat exchanger to transfer that cold fluid back into the ground where it absorbs heat from the surrounding ground and the cycle can begin again.

Q: Is a Ground Source Heat Pump Efficient?

Yes. We believe that a ground source heat pump system, is the most efficient heating and hot water system available for commercial and domestic projects; no matter how large or small. A ground source heat pump uses electricity to operate its compressor and to pump fluid through its circuits. This accounts for around 20 - 25% of the energy requirement for the overall heating system. The remainder of the energy demand comes from the ground and this energy is free. As the heat pump actually generates energy it is a carbon positive technology; you get more energy out than you put in A well-designed ground source heat pump installation typically provides four or even five kilowatts of heat for the consumption of one kilowatt of electricity.

Q: What is the ambient/average room temperature achievable with a heat pump?

Same as gas boiler. Room temps are set by building regulations and the heat pump delivers this in the same way as a gas boiler.

Q: How quickly does it heat the water? With a combi you can have multiple showers and not worry about running out, is that an issue?

Hot water is priority for a heat pump. Usually a 3 port valve is used to ensure the hot water cylinder is kept topped up. If the cylinder drops in temperature (e.g., having a bath or shower), the heat from the heat pump is diverted temporarily from the heating circuit to the cylinder to ensure you don’t run out of hot water. The sizing of the cylinder and the coil within is very important – make sure you ask your installer about this.

Q: What is the cost of installing a ground source heat pump?

The initial purchase cost of a ground source heat pump system is more than a conventional oil or gas fired boiler. The initial capital expense is offset by lower running costs, lower maintenance and low servicing requirement. There is also the security of knowledge that the majority of your heating and cooling energy comes from the ground and will not increase in price. Be careful to avoid judging an installation on price alone. It is very important to ensure you have a well designed system if your aim is to save money over the life of the installation.

Q: What are the financial implications of installing a heat pump through retrofitting over installation into a new build?

Cheaper to install in a new build as there is nothing to strip out and the pipework and radiators will have been designed specifically for low temperatures. The hot water cylinder will also be specifically designed and installed within the new build.