Domestic GSHP FAQs2022-05-17T11:09:51+01:00

Domestic GSHP FAQs

We’ve put together a range of questions and answers to help demystify the tech around Domestic GSHPs.

How Does a Ground Source Heat Pump Work?2022-11-15T09:24:00+00:00

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.

Does a Ground Source Heat Pump provide Cooling?2022-11-15T09:35:31+00:00

Yes. The same components can be designed to provide cooling in the summer.

If cooling is provided in summer, by allowing heat to escape to the ground, then this will improve the performance of heating in the following winter.

You would need to specify this requirement with your installer at the design stage.

Is a Ground Source Heat Pump Efficient?2022-11-15T09:26:21+00:00

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.

What is the ambient/average room temperature achievable with a heat pump?2022-05-10T15:54:53+01:00

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.

Whats normally involved?2022-11-15T09:28:57+00:00

A ground source heat pump installation consists of:

  • a ground source heat pump in your building
  • a ground array for heat exchange with the ground (pipes in horizontal trenches or vertical boreholes)
  • a heat distribution system within your building (underfloor heating, radiators or air ducting)
  • a control mechanism to transfer heat from where it is available to where it is needed.
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?2022-05-10T15:38:56+01:00

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.

What is the cost of fitting a new natural gas boiler compared to a heat pump?2022-05-10T15:54:13+01:00

Gas boiler c.£2500. ASHP c. £8,000. GSHP c. £20,000. Totally dependent on heat load though.

What are the financial implications of installing a heat pump through retrofitting over installation into a new build?2022-05-10T15:38:10+01:00

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.

What is the size of a domestic heat pump system?2022-05-10T15:37:36+01:00

Depends on house size and heat demand. Anything from 3kW for a small flat to 100kW+ for a stately home!

When a new heat pump is installed, is the obsolete central heating pipework removed?2022-05-10T15:36:32+01:00

If the existing pipework can be reused, it will be left in-situ. Ideally, the flow and return pipes from/to your boiler will be used to hook up to your heat pump, albeit with new pipework to the hot water cylinder. But there may be a requirement to change the pipework to fit to the heat pump or possibly to make the pipework bigger. But the pipework around your house should be OK – unless the installer calculates it needs to be upgraded.

What are the noise levels from ground source heat pumps?2022-05-10T15:34:36+01:00

Should be very low, almost like your fridge freezer humming.

How do you deal with some households requiring more resources than others?2022-05-10T15:53:21+01:00

It’s the same philosophy as gas or water supply. Some houses need more water and some need more gas. It is paid for by gas and electric metering. Heat meters are used for the same purpose.

What is the potential to combine multiple technologies such as photo-hydro with air source or ground sound heat pumps with heating water?2022-05-10T15:55:35+01:00

Very good. On-site electricity generation can be used to power some of the heat pump demand. Solar thermal can be used to supplement or replace heat pump in the summer to save money.

As a customer, how would I know they’ve done a heat loss calculator or the installer has done a DNO?2022-05-10T15:51:50+01:00

You need to ask. Also heat loss calcs and Connect and Notify (DNO) is required as part of the MCS process so your installer should do that to remain MCS compliant.

Where the new heating technology is shared across more than one house, how is the electricity supply paid for and can each residents, like now, chose their own supplier?2022-05-10T15:46:18+01:00

This depends on the install.

If one heat pump per house operating on a shared ground loop, electricity used to power the heat pump is usually organised and paid for by the homeowner. The heat pump can be metered or the power to the heat pump will be metered via your electricity meter just as any other appliance in your home.

If a central heat pump supplying heat to multiple homes via a heat network, the owner of the heat network will charge the homeowner a heat price which includes the cost of running the heat pumps and network. You do not pay the electricity directly other than electricity for other appliances in your home.

Where are they manufactured?2022-11-22T11:22:09+00:00

We have heat pump manufacturers in Britain (domestic heat pumps). Others are built all over the world.

I’m really conscious that fabric first build is essential, as we know already our current new build homes are thermally efficient. With this in mind, I am concerned with over heating. Are there cooling options in conjunction with air source heat & hot water pumps?2022-07-19T13:44:59+01:00

Yes – there are heat pumps capable of both heating and cooling. Heat pumps are actually chillers in reverse. You will need to make sure to select a heat pump capable of this in the first place – ask your installer. And you need to make sure your emitters are capable of emitting cool as well as heat. Condensation on pipework can be a problem and normal radiators are not a good type of cooling emitter. Convector radiators are good.

With the switch from gas to renewable electricity, will domestic electric consumer units have to be uprated in respect of supply ampage?2022-05-10T15:32:10+01:00

You will only need single phase electric supply up to 28kWth heat pump. Depending on how full the distribution board is in your house, you may need an upgrade. It is a question to ask your installer and/or surveyor. The installer is also responsible for the Connect and Notify process with the DNO, who will advise if there are local issues with electrical connections.

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