Tap into the warm earth to heat up your home
Those who rely on oil-fired heating are digging deep to find an alternative source of warmth. Sharon Dale reports on the benefits of using ground-source heat to slash your bills.
HAVING lived in a draughty old farmhouse that required gallons of oil to keep it warm in winter, Tim and Samantha Abbey knew they wanted an alternative to expensive fossil fuel for their new home.
The couple decided to install ground source heat when they sold their 17th century farmhouse to a build a more energy efficient property in the village of Long Marston, near York.
The system can cut heating bills by up to 70 per cent in homes that currently use oil and up to 30 per cent in those that use gas. The cost of installation for the average home is between £10,000 to £17,000.
“When we were planning the new home, we thought it was a great opportunity to install a renewable heating source. We had an oil-fired boiler in the old house, which was expensive to run and with the rising cost of oil, we were keen to find something more affordable,” says Tim, a farmer.
He and Samantha, who also run a marquee and hat hire business from home, bought the system from Sheffield-based Danfoss and it was installed by Pure Renewables of Cottingham near Hull.
The first job was to dig trenches about 6ft deep in a nearby field. This was done by a local drainage contractor. Next, piping known as a ground loop was buried in the trenches. The loop carries cold water and antifreeze. This fluid is warmed by the earth and flows back into the 12kw heat pump unit that runs on electricity and is enclosed in a cupboard in the garage.
Here, a refrigerant absorbs the heat and evaporates to form a gas. The gas is then compressed, which causes its temperature to rise. The hot gas passes into a condenser where it starts to change back to a liquid as heat is transferred into the house and supplies the under-floor heating on the ground floor and radiators on the first and second floors. It also heats the hot water.
After passing through an expansion valve, the liquid refrigerant returns to the evaporator and the cycle begins again.
Heat pumps are often describes as working like a fridge in reverse and are effective both in summer and winter, day and night because the ground temperature remains at a constant 12C at only a few feet below the surface.
For the Abbey family, ground source heat has paid off. The system cost £13,000 but their energy bills have been slashed.
Their bill for heating and hot water in their six bedroom home is £750 a year, which is less than a third of the cost of an oil-fired system.
Tim says: “My family really enjoy having a home which is continuously warm after living in an older property that sometimes had ice on the inside of the windows. I would definitely recommend this form of heating to others because it is performing very efficiently. To provide a similar level of heating and hot water from an oil-fired system would have cost at least £3,000 a year. I am amazed at how much money I have saved.
“We’ve had it two years now and it’s fairly easy to run. You just need annual maintenance checks on the boiler and system.”
Ground source heat pumps also attract a one-off Renewable Heat Incentive premium payment of £850 from the government, though householders must also demonstrate that their home is well insulated and they must monitor and record the new system’s performance.
From October 2012, a new RHI scheme is expected to pay homeowners for each unit of green heat they produce.
But ground source isn’t suitable for everyone. Ideally, you will need enough land outside the property to lay the ground loop, which usually extends to about 600ft, though you can use a vertical bore hole system in a smaller space. These are more costly to install.
The pump also works best with under-floor heating or new high efficiency radiators. You can’t have instant warmth as with a conventional boiler as the system is designed to run most of the time at a constant low heat.
The pumps are also best fitted into a new build. Retro fitting is possible though you may also need new radiators and a new boiler.
Chris Dale, director of Danfoss Heat Pumps, says: “An increasing number of farmers and self builders who own land are taking advantage of ground source heat pump technology and enjoying both the immediate benefits of lower heating costs and the peace of mind which comes from being less affected by future energy price rises. Of course they are also helping to reduce carbon dioxide emissions, which means they are doing their bit for the environment too.”
ECONOMICAL: Tim and Samantha Abbey’s ground source heat pump, means their bills are around the third of the cost of oil-fired heating.