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Water source heat pump in Perthshire

Water source heat pump in Perthshire

Heat Pumps are becoming increasingly accepted as a means of heating homes without relying on burning fossil fuels. For anyone who hasn’t had first hand experience of a water source heat pump or any other heat pump, the concept is simple. In the case of ground source, collector loops circulate a glycol/water mix (brine). Energy is absorbed by the brine, typically around 5˚C, and delivered to the heat pump inside the building. Once the energy has been extracted by the heat pump the brine is returned at around 0˚C to start the process all over again.

Where sufficient land is available to install ground loops, the ground array will consist of a number of circuits connected to a manifold. A pair of header pipes link the manifold to the heat pump within the building.

The collector pipes are buried at a depth of at least one metre, where the soil temperature remains stable across the seasons. All energy we extract is ultimately derived from the Sun, and this extracted energy is replaced as rainwater percolates through the soil. The design of the ground loop system considers the amount of energy required by the property, and the ground conditions together with local ambient temperatures.

Water source heat pump in Perthshire Scotland

In addition to burying pipework in earth, collector pipes may also be installed into a loch, or lake. The customary method of installation is a closed loop system. As the name suggests, the brine circulates through a sealed system and there is no interchange between the loch water and the brine circuit. Energy extracted by the water source heat pump is replaced by water flowing into the loch, and solar energy falling on the surface of the loch.

In the winter, temperatures in a lake get close enough to freezing that the colder water is less dense and floats to the top. The water temperature a the bottom of the loch, where he collector pipes are remains pretty much constant at a temperature of approximately 4˚C.

Old England Loch in Perthshire

The installation of water source heat pump collector pipes

A recent project took us to a new build house in Perthshire, Scotland, being constructed within a few hundred metres of a small loch. The available land was considered, and the local loch was presented as a possible heat source. Water is an excellent medium for collecting energy from, and this arrangement made it possible to install the complete collector array with minimum disturbance. Ground loops now more accurately described as loch loops are arranged on land where weights are attached. The loops now take on the appearance of a rope ladder, the rungs adding ballast and serving to keep the pipes apart.

Don kept himself warm!

During installation, our team typically takes a rowing boat out to carry a light rope across the loch, where others of the team wait on the opposite side to reel it in and tow the loch loops out into deep water. Before the pipes are filled, there is enough positive buoyancy to cause the loops to float. Having pulled the loop into the loch to its full extent the loop can be maneuvered into position and the ends of the loops are fusion welded to the manifold on the banks of the loch.

Pumping the glycol-water mix into the pipes has the effect of overcoming the natural buoyancy of the pipe, and the loops sink to the bottom of the loch. Once landscaping is completed and land reinstatement has taken place only the lid of the manifold chamber on the bank reveals the existence of the collector system.

Water source heat pump Scotland

The design of a ground heat exchanger is a complex engineering procedure. Typically, a conservative approach is adopted and early dialogue with us is important to confirm the suitability of a particular tract of land or water source as an energy source before work starts.

For those without packages of land attached to their houses, or access to a loch, do not despair. See our pages on air source heat pumps.

For another project in Perthshire: Underfloor Heating Perth.

Drone images and video: MadeByDrones.

Other images by: STUDIOVHF.

Renewable Heat Incentive scheme further improved!

Renewable Heat Incentive scheme further improved!

The Renewable Heat Incentive (RHI) was introduced to help kick-start the transition to low-carbon heating in the UK, giving help to all in moving from conventional forms of heating to low-carbon alternatives. The scheme provides financial incentives to households and non domestic consumers, including public bodies and charities. It is designed to help bridge the gap between the cost of renewable heating systems and those of conventional alternatives. People who join the scheme and stick to its rules receive quarterly payments for seven years for the amount of clean and green renewable heat their system produces.

Since opening in April 2014, the scheme has already seen thousands of people successfully join and receive payments. That is why the Government is reforming the scheme to ensure it focusses on long-term decarbonisation. It made a number of adjustments as a result of a recent consultation process. The consultation proposed several changes to the existing domestic RHI scheme. Below is a summary of the UK Government’s final proposals in relation to the scheme, which the UK Government intends to implement in spring 2017.

·         The scheme will continue to support all four technologies currently supported, i.e. Biomass, Solar, Air source and Ground source heat pumps 

·         The tariffs for new ASHPs (air source heat pumps) will be increased to 10.02 pence per kilowatt-hour (p/kWh).

·         The tariffs for new GSHPs (ground source heat pumps Scotland) will be increased to 19.55p/kWh.

·         The tariff for new biomass installations will be increased to 6.44p/kWh, the level available between October and December 2015

·         The increased tariff for biomass boilers and stoves, ASHPs and GSHPs will be applicable to those participants who apply to the scheme on or after 14 December 2016 (the date the consultation response was published) although the increased tariffs will only apply from the date the regulations come into force. Participants will receive the existing tariffs for heat used (on the basis of either deeming or metering) before this point. This approach is intended to encourage consumers to continue to install renewable heating systems between the date of the consultation response and the date the changes come into force, to avoid a hiatus in investment and consequential impacts on the supply chain.

·         Heat demand limits will be introduced, to limit the level of annual heat demand in respect of which any household can receive support. The heat demand limits will be set at 20,000kWh for ASHPs, 25,000kWh for biomass boilers and stoves and 30,000kWh for GSHPs. However, this will not disqualify properties with higher heat demands from applying to the scheme. There will be no heat demand limit for solar thermal.

·         All new ASHPs and GSHPs applying for support under the scheme will be required to have electricity metering to monitor their heating system. However, payments will continue to be on the basis of the deemed heating requirements of the property, except for second homes and where a renewable heating system is installed alongside another heating system, in which cases payments will continue to be on the basis of heat metering.

·         GSHPs making use of a shared ground loop will continue to be eligible for the non-domestic scheme and will not be eligible on the domestic.

You can read more about the scheme on these websites: