In addition to recovering heat from the air in your property before you change it for fresh air, it is also possible to gain some additional benefit from the latent heat or coolness in the ground. In a similar way to benefits that can be made from using a ground source heat pump, it is possible to pre-heat or pre-cool the incoming fresh air going into your property by using a Geothermal Heat Exchanger unit.
In the winter, many domestic heat recovery units can switch to a 'frost protection mode' when there are low temperatures of incoming air coming through from the outside. This often means that the supply fan then slows down, causing an imbalance between supply and exhaust air through the unit. Alternatively some machines will turn on a built-in pre-heater which then uses 1-2kW of energy to warm up the incoming air flow.
In the summer, at higher external temperatures, the fresh supply air from the outside can be warmer than the air inside the house, so even if the MVHR unit has a summer bypass which has turned off the recovery function, the incoming warmer fresh air can heat the house. The GEO is a Geothermal heat exchanger unit that will address both issues.
The system comprises of 3 elements - the GEO unit itself, 100m of Geothermal Pipework (to be buried underground) and the Glycol Heat Exchanger Liquid. The GEO system can be used in combination with any heat recovery units up to 500m³/hour output airflow. It is a cost effective solution which gives both pre-heating of incoming air in the winter months and pre-cooling during hotter summer months and could be considered as a very cost effective alternative to comfort cooling if you have enough garden to adequately run the required pipes. The system is easier to install than air ducted systems due to smaller pipework and is a hygenic liquid-filled closed system.