Ground Source Heat Pumps



A Ground Source Source Heat Pump is an efficient and environmentally friendly way of heating your home or workplace using heat drawn from ground, lakes and rivers. It works in a similar way to your fridge at home where heat is removed from food (source) and released to atmosphere through the metal coils on the back of your fridge.

A ground source heat pump reverses this process by removing latent heat present in soil, bedrock or water and releasing it to your heating system inside. There are several methods of heat extraction depending on the heat source. For example, ground heat extraction can be effected by burying lengths of polyethylene pipe in soil and circulating a heat absorbing fluid which moves heat from the soil to the heat pump. Alternatively, the same process can be applied to individual boreholes drilled deep into bedrock.

The two methods are known as “closed loop”  because the means of heat extraction (absorbing fluid) is “closed” to direct contact with with heat source (soil). Alternatively “open loop” refers to heat extracted directly from a heat source, usually heat laden water from ground aquifers. This method involves drilling two boreholes, one to pump water out (extract borehole) and the other (recharge borehole) to take water back into the aquifer when heat has been extracted. Ground Source Heat Pumps can be used to provide heat for underfloor heating, radiators and warm air convectors, and supply all of your hot water requirements.

The great advantage of ground source heat pumps is that for every unit of electrical energy consumed, free environmental heat units are captured and with vast amounts of solar heat stored in soil, bedrock and water, it makes the ground source heat pump the most efficient renewable heating technology currently available. For example, a typical ground source heat pump will generate 1kw of electrical heat and 3/4kw of environmental heat for every unit of electricity consumed giving an efficiency rating of 1:4/5 or 400/500%. Compare this to a traditional gas or oil system with standard efficiencies of no more than 90%. With a projected life span of between 15 and 20 years, your ground Source Heat pump guarantees future proofing against rising fuel prices as the renewable energy units captured from the source will always remain FOC.


At The Underfloor Superstore we offer a comprehensive range of ground source heat pump products from industry leading manufacturer Stiebel Eltron.

For a FREE heat pump quotation or consultation call our sales team on 01283 850045 or click here to email us.



RENEWABLE HEAT INCENTIVE (RHI)

RHI is a government run incentive scheme designed to encourage the take up of renewable energy by paying owners of eligible technologies for the renewable heat generated. In the case of domestic owners, payments are made over 7 years whilst commercial owners receive payments over 20 years. RHI is index linked to inflation.

For Domestic customers, there are two further qualifying criteria to gain acceptance onto the RHI scheme. Firstly, your property must have a compliant green deal assessment attesting to minimum insulation levels required within your property and secondly, you must have a valid MCS certificate. MCS certificates can only be issued by accredited installers or installers operating under an MCS accredited umbrella scheme. The Underfloor Superstore is completely flexible in that we operate an MCS umbrella scheme allowing your chosen installer to do the work or we can recommend installers from our network of accredited installers.

Financial Benefit – Working Example
Mr Y is building a four bedroom rural property set in 3 acres of land with insulation levels slightly better than current building regs. He has a Green Deal Assessment indicating a heat load figure of 28,000kwh covering heating and hot water.
With ample land available, he has opted for a ground source heat pump closed loop system with 6 x 100 Metre lengths of polyethylene pipe buried in in 6 x 50Metre trenches.
The cost of installing the 12kw Ground Source Heat Pump and underfloor heating is £25,000 compared to around £7,000 for an oil heated system. (Diff = £18,000)
Mr Y will save around £715 per year in running costs compared to the oil system. He will also receive £3,400 per year in RHI payments for 7 years. With total benefit of £4115, the recovery period to reach parity with Oil system is £18,000 / £4,115 = 4.37 years. Thereafter, Mr X is £4,115 better off per year for the remaining 2 ½ years and £715 per year thereafter.

A ground source heat pump will require extra investment in the short term, which you will recover in the medium term through cheap energy bills and RHI income. Over the longer term, on-going lower running costs will deliver a significant return on your investment, especially when substituting fuel sources such as solid fuel, oil, LPG or direct electric.


ENVIRONMENTAL & LIFESTYLE BENEFITS

Primary fuel for ground source heat pump is the freely available solar heat trapped in soil, bedrock or ground water. Depending on the fuel being substituted, carbon emission savings can be as high as 3.6 to 10.5 tonnes per year.

A Ground  Source Heat Pump is a “fit and forget” technology which doesn’t require you to interact with it in any way once it is installed. Service and maintenance is minimal as there is no on-site combustion taking place. A once per year service is generally all you will need.


WILL A GROUND SOURCE HEAT PUMP WORK FOR ME?

There are a few basic qualifying answers to the questions you should ask yourself when considering whether a heat pump will work for you and your property.
If you find yourself ticking these boxes and wish to speak to one of our team about your specific project, don’t hesitate to get in touch.

√ - Apart from ASHP, my only other fuel options  are Oil, LPG, Direct Electric, Solid fuel
√ -I will be using low temp heating ( underfloor heating, oversized rads )
√ -I can add more radiators if necessary to reduce system flow temperatures.
√ -My property is either well insulated or can be improved
√ -I have got room enough to site outdoor unit ( at least 5m away from neighbour )
√ -I have got room to site a domestic hot water tank and maybe a heating buffer tank
√ -I want to save money and future proof my property against rises in energy costs.


FAQ'S

Q - Do heat pumps need a back up boiler? Can they provide all heating and hot water without it?
A – Heat pumps don’t need a back up boiler when they are designed to cover full heating load. However, heat pumps and boilers can work together in situations when it is cheaper to run the heat pump to one set temperature and the boiler to another. For example, a retro-fit situation where existing infrastructure can’t be changed, the heat pump will operate as the lead heater for majority of the time, only switching to boiler on coldest days.

Q
Do you need a lot of land?

A – In some cases yes, in others, no. A ground source heat pump with trenches will require a significant amount of land. If there is not enough land available, boreholes take up less space so might be a suitable option.


QAre heat pumps any good at heating Domestic Hot Water to higher temperature?

A - Typically, heat pumps will heat domestic hot water to a temperature of around 50 to 55°C which is perfectly adequate for system users who will experience a mixed down tap temperature of 41-43°C. The only consequence of a lower domestic hot water temperature is the requirement to run a  periodic legionella cycle whereby cylinder immersion heater is energised once every few days to lift the temperature to 60°C and hold it for an hour.