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Ground Source Heat Pump Information page

Ground Source Heat Pumps Explained

Types of GSHP systems

GSHP systems can be installed almost anywhere providing the conditions allow. We can install into a city building with little site room available, or out in the country where a different approach can be taken. The heat energy acquired can be used for a variety of different purposes; under floor heating and cooling, heating swimming pools, domestic central heating and cooling, all types of glasshouse plus many commercial applications. There are several ways of collecting the latent heat from the earth adjacent to your property; the method that best suites you will of course depend upon a number of factors, these include:  site location, size, available access, underlying soil type/rock strata and resources available locally. Explained briefly below are the most common types of installation.

Open Loop Systems

Heat sourced from a borehole or watercourse is extracted and then returned to the environment (or stored for other uses). This method would be the obvious choice for properties with an existing borehole, stream or lake. It also eliminates the risk of localised chilling of the earth mass, but requires careful design and implementation.

Closed Loop Systems

These involve a circuit of pipework through which an antifreeze solution (Filterclean use an environmentally friendly vegetable based/non toxic product) is pumped.  Horizontal ground loops are generally placed in a series of trenches and are relatively straightforward to install, however, they often require plenty of space. Vertical loops can be used where space is limited, although this approach requires the drilling of boreholes to accommodate the ground loop. Somewhere in between sits the "slinky" installation, which packs more ground loop surface area in a smaller space. The above methods can all be considered as ‘closed-loop’ systems, as the heat collecting media is re-circulated.

There is a risk with closed loop systems that, if not carefully designed, the earth mass from which heat is extracted becomes chilled due to unsustainable heat extraction. This chilling effect will impact on GSHP efficiency and so care must be taken to ensure ground loops cover an adequate area.  We size our systems with the aim of not changing the ground temperature by more than 1 degree Celsius over a fifty-year period.

Bodies of Water  

Open or closed-loop methods can be used to take advantage of latent heat in adjacent bodies of water, such as ponds, lakes or streams. These are very efficient at transferring heat from the surrounding landmass. Utilizing a lake or pond often leads to a significantly less complicated installation. Again we take care in this instance to ensure that we do not overcool the surroundings.

(Click here for further information, system sizing and technical data)

System sizing

Ground Source Heat pumps are available in differing kilowatt ratings and will be sized along with the type and length of the ground loop dependent upon a number of factors including, but not limited to; Heat loss of the property - This will be calculated by the architect, obtained by best-fit models or found in the Standard Assessment Procedure (SAP) for new builds. Size of the property - Total floor area including all levels. Size of land available for ground loop - Horizontal loops are the cheapest and most efficient but require a lot of space to install. The space you have available will dictate the loop type. Soil type / rock type - Plays a significant part in the sizing of the ground loop and heat pump, generally heavy soils are more efficient at transferring heat that lighter sandy soils. A geological survey will be required if vertical loops are used, granite is the most efficient while sedimentary rock is less so. Amount of Domestic Hot Water - The system has to be designed to cope with peak hot water usage for the property.

All the  information above will need to be gathered in order to put together an accurate cost for installing the system.

Installation pictures

Laying horizontal loops	Slinkies	Typical heat pump	Underground connections	GSHP Heated pool

Advantages

Some of the advantages of heating by GSHP are:   

• Save up to 75% on energy bills

• Fulfill all domestic heating requirements from an existing borehole or lake

• No need for a conventional oil/gas boiler or fuel connection

• Low carbon footprint 

• No unsightly bulk storage

• No need for a flue

• No explosion or carbon monoxide risk

• Protection from fluctuations in the oil and gas markets

• Maintains efficiency throughout service life *

• Up to 600% efficiency possible with open-loop systems

• Especially suited to use with under floor heating**

• All ground loop joints electro-fused for a long service life

• Can be used as a heat source for water to air systems and conventional central heating systems**  

• Systems can be designed to reverse cycle to cool the property during the summer if needed

* The efficiency of a GSHP will not degrade over time to the same extent as an oil or gas boiler for example, though this statement assumes stability of any geothermal heat source.

 ** To ensure maximum efficiency internal heating systems must be correctly sized