Heat

Ground source heat pumps (GSHP) are an increasingly popular option for delivering low-carbon space heating (and cooling) for commercial, public and domestic buildings.

The principle of ground source heat pump technology is long-established and is based on the same process as the common domestic refrigerator. A quantity of thermal energy is removed from one source and transferred to another.

In the case of a refrigerator, the energy is removed from the inside of the appliance (cooling the air inside as a consequence) and transferred to the heat dissipation coils on the back of the cabinet. In the case of GSHP, the energy is removed from the ground and transferred into the interior of a building.

In both cases the energy source becomes chilled, and the energy sink is warmed.Which system to choose?

There are two principal methods for supplying thermal energy to the source-side loop in GSHP applications:

Closed Loop Systems utilise, as the name suggests, a system of plastic pipes which simply circulates fluid (water and environmentally friendly anti-freeze) through the ground absorbing heat (heating) or rejecting heat (cooling). The Heat Pump either increases the temperature for heating or decreases it for cooling, dependant upon the needs of the building.

In a currently unregulated industry in the UK (unlike the USA), there are unqualified people from all walks of life designing and installing fairly sizeable Closed Loop Systems. Closed Loop Systems need to be designed by people trained and qualified to do so. In reality, borehole depths generally range from 40m to 200m and the ‘output’ or ‘input’ capacity of a borehole could vary by a factor of ten. Whilst it is acceptable to use generalised estimations for initial concept work, this should be left behind once at Stage B and this is where a company such as Heat Air LTD should drive the project forward in an informed way.

Even a badly designed Closed Loop System may work initially! It may take many months or even years for the ground loop to overheat or freeze. The System may continue to work, however, it will be inefficient and unsustainable and any carbon reduction targets would be missed. At worst, the System could fail altogether.

An Open Loop System involves pumping water from an existing source, perhaps a river or a lake, but more often via boreholes that are drilled to access water sources below ground for efficiency.

The water either travels directly to the integral Heat Pump or more commonly via a Plate Heat Exchanger.

An Open Loop System involves pumping water from an existing source, perhaps a river or a lake, but more often via boreholes that are drilled to access water sources below ground for efficiency.

The water either travels directly to the integral Heat Pump or more commonly via a Plate Heat Exchanger.All Open Loop Systems using over 20m3 of groundwater per day are subject to lengthy and complex Environmental Agency (EA) Regulations.

The EA are reasonably relaxed about Open Loop Groundwater Systems if spent water is returned to the aquifer from which it was taken, meaning that net permanent consumption is relatively small.

It must be demonstrated to the EA that the System is not going to affect an existing user of groundwater in the vicinity of the Project and that it offers no potential threat to the environment.

Heat Air LTD Designers, Project Managers, Hydrogeologists, Groundwater Modellers and Supervising Engineers work very closely with EA officers to ensure that the Scheme will operate within EA guidelines and just as importantly, we will demonstrate the sustainability of the System.