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Did you know the UKs leading manufacturer of ground source heat pumps is based right here in Cornwall?

We have put together a list of the six most frequently asked questions from UK self builders when they are considering using a ground source heat pumps.

  1. How do heat pumps work?

Ground source heat pumps (GSHPs) extract warmth from the earth via pipes in the ground or water sources and upgrade this to provide heat and hot water in the home. Heat pumps are powered by electricity, but this doesn’t have to be sourced 100% from the grid – they function well alongside other renewable tech such as solar PV to provide a sustainable heating setup. Watch Kensa’s animation on how a ground source heat pump works here.

  1. What tech will the pump work alongside; can the same unit offer space heating and hot water; can it work off-grid?

Ground source heat pumps work best with underfloor heating due to the large surface area and typically operate at 35°C – 45°C flow temp. The most common method is a combination of underfloor heating on the ground floor and radiators to the first floor. A low surface temp radiator should be selected, these will usually be over-sized with a flow temperature of 40°C – 50°C. A ground source heat pump deliver space heating and domestic hot water. Heat pumps can work off grid with the right equipment.

  1. Will the unit be noisy and where in the home should it be installed?

The unit operates around 52dB, a similar noise to a dishwasher. Depending on the size heat pump required, it can be located externally in a weather proof shelter or plant room, or inside the home typically within the hot water cupboard; Kensa’s Shoebox heat pump is the smallest and quietest ground source heat pump on the market, designed to be installed inside the home.

  1. How much does a system typically cost, including installation, and what results will it achieve?

A ground source heat pump will provide all of your space heating and domestic hot water requirements and will typically cost in the region of £10,000 – £12,000, however the running cost savings plus the income from the Government’s Renewable Heat Incentive (RHI) will more than offset the capital cost.

With ground source heat pumps you have many options of heat sources which can influence costs, too; soil, rock, and water. The cost of the installation can vary according to the choice of heat source; boreholes tend to be the costlier option but they are the quickest and most compact form of ground array – great for sites with limited space, whereas when water sources are available ‘pond mats’ offer the least costly option as minimal ground disruption is required.

To see how much your system could cost and earn you click here.

  1. What is the lifespan of the system and what maintenance will it need?

A ground source heat pump will last for 25 years, and has no servicing requirements. This translates to low ongoing lifetime ownership costs and savings of up to 50%.

  1. What are the pros and cons of ground source heat pumps in comparison to air source systems?

In terms of a ground source heat pumps performance and how this can impact costs, for every 1kW of electrical energy you can expect 3kW of renewable heat (this is referred to as a Coefficient of Performance, you can expect a COP of around 4:1 at 0°C/35°C).

The COP will vary depending on the operating conditions of the heating system and the incoming ground temperature. Multiple studies across Europe demonstrate that ground source heat pumps are typically around 20% more efficient than air source heat pumps. This is entirely understandable as the average ground temperature throughout the winter heating season is higher than the average air temperature, which means the ground source heat pump does not have to work as hard to upgrade the source heat to that required for space heating and hot water.

This superior efficiency is only half the story. It is very likely that future electricity tariffs will feature split rates depending upon when the electricity is consumed.  Almost certainly, the lowest tariffs will be available for night-time operation when there are lesser demands. The challenge will be to find ways to shift a household load to these periods. An immediate option would be to re-charge the hot water cylinder through the night. A future option might be to store heat perhaps utilising phase change materials. Either way, an air source heat pump usually operates at its lowest efficiency through the night since the air temperature is usually significantly cooler at 2am than 2pm. Plus the noise of the circulation fan will not aid sleep.  Meanwhile, the prevailing air temperature does not impact the performance of a ground source heat pump since the ground arrays are buried at sufficient depth to be insulated from these variations (ground temperature year round typically range from 8°C – 12°C; an air source heat pump uses external air which can vary by as much as 30°C across the year, between -7°C & 23°C).

Ground source heat pumps also accumulate greater RHI returns (currently 19.33p per kWh – the air source heat pump tariff is currently 7.51p per kWh). In addition to this they have no requirement for planning permission, and no need for annual servicing or maintenance.

For more comparisons between ground source heat pumps and other heating technologies click here.

This blog was provided by Kensa Heat Pumps