Isoenergy install the correct, most efficient Ground Source Heat Pumps to provide the best return on investment. Our Tamworth project with Premier Inn is returning a staggering 6.25kWs of heating and hot water for every kW used to run the system!

Ground Source Heat Pumps (GSHP) operate on the same principles as a domestic fridge, but differ in the ways they retain heat and recycle cold. The temperature of the earth at one metre below ground remains between approximately 9 to 12 degrees consistently throughout the year depending on geographical location. Contrary to popular belief this is due to solar heat stored in the ground, not geothermal heat from the centre of the earth. An installation will typically consist of a heat pump, ground loops, a manifold and manifold pit, circulation pumps, automatic and manual valves, an expansion vessel, a filling set, a buffer tank, a hot water cylinder, a control system and an additional heat source if required. Generally GSHPs have built-in circulation pumps, making it easy to connect to the heating medium and collector circuits.

Ground Source Heat Pump Basic Principles.

The basic principles of the GSHP begin with the absorption of heat from the heat source (rock, ground or lake). This is achieved through a closed collector system containing water mixed with vegetable based antifreeze. These collectors are predominantly placed in long runs in the ground but can also be coiled up and placed in a body of water (as there is an abundance of usable energy, coiled piping will not extract too much energy) or placed vertically into the ground in boreholes.

Closed Loop Collectors for a GSHP.

For horizontal ground loops, using a lake as the heat source is the most preferable option, as it has the best heat transfer qualities. Installing the collector in a lake or any permanent water source will also drastically reduce the necessary collector pipe length. In short, the wetter the better. Installs using closed loop collector pipes in the ground also follow these rules: collectors in wet sandy soil or wet clay are always positive. Dry media is the least suitable, as it is the least effective transferor of heat therefore the pipe lengths required can increase hugely as it takes longer to both disperse the cold and absorb heat from the earth.

Boreholes.

When a lake or sufficient ground for loops is unavailable, drilling boreholes becomes an option. In the UK drilling can be an expensive exercise due to the unpredictable make-up of the ground. Isoenergy can recommend a trusted drilling contractor to ensure you receive the most affordable drilling solution.  

GSHPs (Ground Source Heat Pumps) take latent solar energy stored in the ground and compress it to heat your house and/or provide hot water.

The main way of extracting heat for use in a GSHP system is by using plastic tubing. This system is placed in the ground, in a borehole or in a body of water. An environment-friendly, non-freezing liquid circulates in the tubing and delivers the collected heat to the heat pump. Once in the heat pump, the heat is converted into high-grade heat for space heating and/or hot water.

The Stages Inside a Ground Source Heat Pump.

1. Heat is absorbed from the heat source (rock, ground or lake) through a closed collector system containing water mixed with vegetable based antifreeze.
2. The collector fluid then emits its heat to the refrigerant in the heat pump's evaporator.
3. The refrigerant vaporises and is then compressed.
4. The refrigerant, with its increased temperature, is led into the condenser where it emits its energy to the heat medium circuit, and therefore provides heating to the home, the hot water cylinder or both.

Renewable Heat Incentive.

From July 2011, Ground Source Heat Pumps will be able to qualify for the Renewable Heat Incentive (RHI).

When Ofgen announces its qualification criteria, Commercial properties will be paid 4.3p per kW for systems under 100kW and 3p per kW for systems over 100kW for 20 years.

Domestic properties will be eligible from October 2012.

The Incentive will be paid based on metered systems, perfectly placing isoenergy's high performance, highly efficient systems in a position to reap the greatest benefits for our customers.

For more information, see our Renewable Heat Incentive FAQ or our News section.

A heat pump can generally reduce energy bills by around 70% when compared to oil.

When run efficiently at about 45 degrees centigrade, heat pumps can produce four or even five times as much power as they use. This is called Coefficient of Performance (COP) and means that for each kilowatt of energy provided to the heat pump, 5 kilowatts of energy will be provided to your house.

Our recent Whitbread project is producing an average COP of 6.25!

Docking to backups or existing systems.

With older properties, the ideal level of insulation required for a GSHP to be fully effective during the very coldest days of the year cannot always easily be achieved.  The harder a GSHP has to work the less efficient it is and the further its COP will drop. Therefore in some cases we suggest supplementing the coldest days with an auxiliary system, such as an existing oil boiler.

Isoenergy has extensive experience installing GSHP systems in all types of buildings, and has unparalleled knowledge of installing in large scale country houses and listed buildings.

We are fully MCS accredited and perfectly poised to install Renewable Heat Incentive eligible systems.