Ground Source Heat Pumps
2.) Bore Hole ground Loops
A bore hole installation will require drilling a bore hole to a depth of between 50-150m into the ground and lowering two pipes connected with a U bend at the bottom all the way down to the bottom of the bore hole. These pipes are piped back to the heat pump. The depth and number of bore holes will depend on the size of the property and the size of the heat pump.
Ground source heat pumps (GSHP)
A GSHP extracts its heat from the ground which has absorbed its energy from the sun. Unlike ambient air temperature the ground temperature remains reasonably consistent throughout the year, typically at 8-12 degrees depending on how deep you go into the ground. The deeper you go the less the seasonal ambient temperature will affect the ground temperature. Due to the consistent temperature of the ground, a GSHP’s electrical consumption remains reasonably consistent and easy to predict.
Unlike an ASHP a GSHP is generally installed within the property with pipe lines extending from the unit to the ground, these are called ground loops and contain an anti-freeze water solution called brine.
Ground & Air Pumps – overview
A heat pumps size will depend on the size and thermal efficiency of the property being heated. A SAP calculation will need to be carried out to ascertain the heat load required for the building.
A heat pump is designed to generate temperatures up to 55 degrees. Due to this temperature heat pumps are generally better suited to new build properties which are built with high insulation levels.
Heat pumps are also suited to retrofit installations. If retrofitting a heat pump to an existing properties heating system there will possibly be some incidental works to be considered at the design stage. These could be improving the thermal efficiency of the fabric of the building and replacing existing radiators with larger more efficient types due to low flow temperatures.
Underfloor heating is a preferred heat emitter when combining with a heat pump as underfloor heating requires lower flow temperatures than a radiator due to underfloor heating covering a large surface area.
In most circumstances, a heat pump system will be designed to deliver full heating and hot water demand. In circumstances where the heat pump can’t achieve the full heating load all year round then a backup heat source will need to be factored into the system design like an immersion heater or boiler.
Solar thermal systems and photovoltaic solar panels are a good option to consider when choosing to install a heat pump. A solar thermal system would cover the hot water demand in the summer time allowing the heat pump to be turned off and only used as a backup. Photovoltaic panels would generate electricity to support heat pump electrical consumption.