The ground array for a ground source heat pump is essentially its fuel source. Its design is 100% critical to the success of the installation. There must be sufficient pipe buried in the ground, and that pipe must be spread over a large enough area so energy extraction is sustainable (i.e energy returned by solar irradiation or rainfall is greater than that used in the property) over the course of a year.
There are essentially five types of ground array we specialise in. We can provide complete kits, incorporating design warranties for each of the system types below:
- Horizontal Ground Collector – Here the collector pipe is buried at a depth of 1m in open trenches. The trenches are excavated a meter wide, and each loop is laid down a trench, with the pipe tucked against each wall. Trenches are separated by ideally 4-5m. Open trenching is very affordable compared to drilling, so a preferred option if sufficient open ground is available. The quantity of pipe required is calculated by looking at the heating and hot water load of each building, and then comparing that with the thermal conductivity of the ground type found at the property. We have created a basic design guide for horizontal collectors enabling you to see if sufficient ground area is available at your property. (Click here for the layout of the Horizontal Ground Collectors)
- Vertical Ground Collector (Boreholes) – If sufficient flat open ground is not available at a site, an alternative option is to drill a 6” borehole and insert a pair of pipes with a U bend at the bottom. The depth and numbers of boreholes required depends on the conductivity of the geological formations below the property, which is largely linked to the water table. Spire will recommend a driller depending on your area, we have many partners we have worked with previously. We have created a basic design guide for horizontal collectors enabling you to assess the most suitable area for boreholes can be found at your property. (Click here for the layout of the Vertical Ground Collectors)
- Flowing Water Collector (Energy Blade) – A flowing stream is the ultimate energy source. For surface flowing water we are re-sellers of the Energy Blade For a single four plate assembly up to 18kW of energy can be extracted from an extremely compact, durable product. It can be secured to the stream bed or hung in a water column from above. EA permissions may be required for installing the blades at certain sites, please contact us for more details.
- Static Water Collectors (Slinkies) – For the best method of extracting energy from a non-moving water body, we recommend the use of slinky collectors. These are looped lengths of 40mm, cable tied then weighted with engineering bricks so they sink once filled. Secured out across the lake so they are well separated, the slinkies make perfect collectors. The use of a lake to extract energy reduces the need for trenching, making this one of the most affordable ways of installing a GSHP. If you want to know if your lake is big enough to heat your property, please get in touch.
- Groundwater Energy Extraction (Open Loop) – For certain sites across the UK, the water table is very close to the surface. Providing the water found there is low in sediments, iron or corrosive chemicals it can be brought to the surface and the energy stored in it can be extracted by a heat pump before it is returned back to the ground. Ultimately, the fact that you are only sinking two boreholes means that your drilling cost is substantially less than a vertical ground collector, however there is a regular maintenance requirement for the cleaning of various filters and a higher running cost when taking into account the borehole pump set underground. If you want to know whether your site is in an area suitable for groundwater extraction, or require system advice / design then please contact us.
