Ground source heat pumps use a buried ground loop which transfers heat from the ground into a building to provide space heating and, in some cases, to pre-heat domestic hot water. The efficiency of a ground source heat pump system is measured by the coefficient of performance (CoP). This is the ratio of units of heat output for each unit of electricity used to drive the compressor and pump for the ground loop. Average CoP over the year, known as seasonal efficiency, is around 3-4 although some systems may produce a greater rate of efficiency. This means that for every unit of electricity used to pump the heat, 3-4 units of heat are produced, making it an efficient way of heating a building.         

How much do they cost?
Ground Source Heat Pumps cost a little more than a boiler but the payback period can be as short as 4-5 years and save you up to 75% compared to traditional methods.

How do Ground Source Heat Pumps work?
They work like a fridge by moving energy from one place to another. For example, a bottle of wine brought from your local supermarket is at room temperature. If you put it in your fridge and wait a few hours it will be cold enough to drink. If you touch the back of your fridge during that time you will feel heat. The fridge has taken the low temperature energy out of the wine, compressed it up to a higher temperature and in effect has warmed the kitchen up slightly. By using the same process Heat Pumps remove solar energy stored in either the earth, air of water around your building, compress it to a higher temperature and transfer it into your central heating system and hot water tank. They are also known as geothermal, ground source, earth energy, air source, water source heat pumps.

Does the Ground Source Heat Pump work all year round?
Yes this system provides heating and hot water 365 days a year.

How long do the Ground Source Heat Pump units last?
Typically each Ground Source Heat Pump unit will last around 25 years. This includes the actual pump and the pipe which is buried in the ground. The pipe is impervious to corrosion and tree roots and comes with a 50 year warranty.

How much annual maintenance is required on a Ground Source Heat Pump?
No annual maintenance is required.

Are there any warranties available?
Yes, we provide a full 5 year parts and labour warranty for all our Ground Source Heat Pumps.

Where are Ground Source Heat Pumps located?
The heat pump should ideally be located on a ground floor (ideally in a utility room or garage on an eternal wall). The pipe loop is buried within the ground up to a depth of 1 metre and is not visible. A manifold type system is used where more than two pipe tails are present which is located within a manhole. A single flow and return is then taken into the utility room or garage where the heat pump is situated. This can be through the wall or up through the floor.

How much space do I need for my Ground Source Heat Pump?
The heat pump unit has the same footprint of a dishwasher and stand between 1.4m a to 1.8m and will fit in any model dwelling which has been constructed to UK standards (ceiling height is 2.3m) Space of 300mm should be allowed to one side of the unit to connect the ground loops.

What is suitable for a Ground Source Heat Pump installation?
Ground source heat pump installations are suitable for all new build and renovated building ranging from small houses, flats, apartment to schools and offices and spaces where heating and hot water are required. Where land area is restricted for the loop installation a ground source heat pump may not be suitable. An alternative would be either boreholes (which can be expensive) or an Air Source heat pump.

What is not suitable for a Ground Heat Pump installation?
Older buildings which have not been renovated and have no plans for renovation of heating system upgrade are generally not suitable for ground source heat pump technology. This is because the heating distribution system would have been designed for higher temperature water and its effectiveness at lower temperatures cannot be guaranteed. All new buildings from 1996 to present have been designed with thermal efficiency in mind, unlike properties built prior to this. A full or partial renovation of an older building and replacement of the heating system would normally allow for a ground source heat pump installation.

Do Ground Source Heat Pumps require single phase of three phase electrical supply?
We can supply heat pumps in either single or 3 phase.

Will I need a new boiler?
In most cases a Ground Source Heat Pump can be designed to supply all of the heating and domestic hot water without the need for support from a boiler (Gas, Oil & LPG).

How Much Hot water is produced each day by a Ground Source Heat Pump?
The system can provide all of your hot water for baths and showers. Mains pressure water tanks are available in sizes of 180 litres up to 1000 litres which. 180 litres is suitable for a domestic installation with a family of 4.

How green are Ground Source Heat Pumps?

1. The ground loop. This is comprised of lengths of pipe buried in the ground, either in a borehole or a horizontal trench. The pipe is usually a closed circuit and is filled with a mixture of water and antifreeze, which is pumped round the pipe absorbing heat from the ground.
2. A heat pump. This has three main parts:
   • the evaporator - (e.g. the squiggly thing in the cold part of your fridge) usually a ground loop, takes the heat from the ground with the use of refrigerants
   • the compressor - (this is what makes the noise in a fridge) moves the refrigerant round the heat pump and compresses the gaseous refrigerant to the temperature needed for the heat distribution circuit;
   • Heat exchanger - the refrigerant gives up heat to a hot water tank which feeds the distribution system.
3. Heat distribution system. Consisting of under floor heating or radiators for space heating and in some cases water storage for hot water supply.

What options are available?
The ground loop can be:

1. Borehole;
2. Straight horizontal - trench costs less than a borehole, but needs more land area;
3. Spiral horizontal (or 'slinky coil') - needs a trench of about 10m length to provide about 1kW of heating load.

Running costs

The efficiency of a GSHP system is measured by the coefficient of performance (CoP). This is the ratio of units of heat output for each unit of electricity used to drive the compressor and pump for the ground loop. Typical CoPs range from 2.5 to 4. The higher end of this range is for under-floor heating, because it works at a lower temperature (30-35°C) than radiators.

Based on current fuel prices, assuming a CoP of 3-4, a GSHP can be a cheaper form of space heating than oil, LPG and electric storage heaters. If grid electricity is used for the compressor and pump, then an economy 7 tariff usually gives the lowest running costs.

Ground source heat pumps and your home

What to keep in mind when considering a ground source heat pump.

1. The type of heat distribution system. GSHPs can be combined with radiators but under-floor heating is better as it works at a lower temperature.
2. Is there space available for a trench or borehole to accommodate a ground loop?
3. Is the ground suitable for digging a trench or borehole?
4. What fuel is being replaced? If it's electricity, oil, LPG or any other conventional fossil fuel the payback will be more favorable. Heat pumps are a good option where gas is unavailable.
5. Want to be 100% renewable? Buy green electricity, or install solar PV or some other form of renewable electricity generating system to power the compressor and pump.
6. Need a back-up heating system?
7. Is there also a cooling requirement?
8. Is the system for a new building development? Combining the installation with other building works can reduce costs.
9. Can you incorporate insulation measures? Wall, floor and loft insulation will lower your heat demand.

In most circumstances a heat pump, should be able to provide all of the heating and water required for the home.