Ground Source Heat Pumps

Heat pumps work by moving heat from one place to another. In the case of ground source heat pumps, the sun’s heat is collected from the ground (or a body of water) via a circulating loop of glycol (antifreeze). When the loop reaches the heat pump a refrigerant circuit extracts the heat energy which is then used for heating and hot water.

The magic of heat pumps is that they can use ground with an average temperature of 10 degrees to heat hot water to up to 60 degrees all year round. This is because, although the ground loop may only gather a few units of energy per metre of the loop, it makes this small gain across a very large area in which the heat is constantly replenished by the sun and precipitation. This adds up to a lot of units of energy which can then be concentrated into the relatively small area of your home.

 

Your garden needs to be around 3 times larger than the floor area of your property for a horizontal loop (for new build homes twice as large should be sufficient) .Vertical borehole loops can also be used in some situations where this area is not available. You will need access for a digger or drilling machine. If you have a large pond, stream or access to other water you might want to consider siting your loop in the water, as water transfers heat even more efficiently than soil.

For fault-free operation, heat pumps require a minimum flow rate of heating water. We recommend using a buffer cylinder in order to ensure trouble-free heat pump operation. Amongst other things, buffer cylinders provide hydraulic separation between the heat pump circuit and the heating circuit. For example, if the flow rate in the heating circuit is reduced via thermostatic valves, the flow rate in the heat pump circuit remains constant.

For air source heat pumps the need for a buffer is even greater than for ground source pumps. The heat exchanger in air source pumps runs much colder than ambient temperatures, and as a result it becomes frosted with ice. Air source pumps must periodically work in reverse to defrost the exchanger. A buffer tank provides a source of heat to steal for this purpose, without robbing heat from the property being heated. Without this dedicated store of heat, an air source machine can start to take heat from a house, actually reducing the temperature of the property in a downward cycle.

Heat pumps, like cars, are less efficient if they start and stop frequently. Buffer tanks allow a pump to run for longer periods of time increasing efficiency. If a single room calls for heat it can use energy stored in the buffer tank first, delaying the need to start the pump again.

The size of the project dictates the size of the heat pump(s) required. As a guide, a ground source heat pump is around 600mm x 600mm (same size as a fridge) but projects often also require a buffer tank, these range in size according to the project.

Total NRG is a family run business with a high quality ethos. To provide our clients with practical and efficient solutions, which match their specific requirements, we manage the whole process from beginning to end

“For over a decade Bryan Jones has been a leading light in the drive to promote renewable energy in the UK.
While working as a heating engineer, Bryan came to understand the importance of the energy we use for modern life and the effect it has on our planet. He became passionate about exploring the alternatives to fossil fuels that were available in his industry and founded Total NRG to bring these alternatives to his customers.”

Bryan Jones

Managing Director