Yorkshire Post - Property - - NEWS -

Ground source heat pumps use pipes buried in the gar­den to ex­tract heat from the ground. This is usu­ally used to heat radiators or un­der­floor heat­ing sys­tems and hot wa­ter.

How does a ground source heat pump work?

A ground source heat pump cir­cu­lates a mix­ture of wa­ter and an­tifreeze around a loop of pipe – called a ground loop – which is buried in the gar­den. Heat from the ground is ab­sorbed into this fluid and is pumped through a heat ex­changer in the heat pump. Low grade heat passes through the heat pump com­pres­sor and is con­cen­trated into a higher tem­per­a­ture use­ful heat ca­pa­ble of warm­ing wa­ter for the heat­ing and hot wa­ter cir­cuits of the house. Ground loop fluid, now cooler, passes back into the ground where it ab­sorbs fur­ther en­ergy from the ground in a con­tin­u­ous process while heat­ing is re­quired.

The length of the ground loop de­pends on the size of your home and the amount of heat you need – longer loops can draw more heat from the ground, but need more space.

Nor­mally, the loop is laid flat or coiled in trenches one to two me­tres deep, but if there is not enough space in your gar­den you can in­stall a ver­ti­cal loop down into a bore hole to a depth of up to 100 me­tres.

Heat pumps have some im­pact on the en­vi­ron­ment as they need elec­tric­ity to run, but the heat they ex­tract from the ground, air, or wa­ter is con­stantly be­ing re­newed nat­u­rally.

Un­like gas or oil boil­ers, heat pumps de­liver heat at lower tem­per­a­tures over much longer pe­ri­ods. This means that dur­ing the win­ter they may need to be left on 24/7 to heat your home ef­fi­ciently. It also means that radiators should never feel as hot to the touch as they would do when us­ing a gas or oil boiler.

Is your gar­den suit­able for a ground loop?

It doesn't have to be par­tic­u­larly large, but the ground needs to be suit­able for dig­ging a trench or a bore­hole and ac­ces­si­ble to dig­ging ma­chin­ery. The out­put from the pump varies from site to site be­cause soil con­di­tions can have a sig­nif­i­cant im­pact on per­for­mance.

Is your home well in­su­lated?

Since ground source heat pumps pro­duce a lower tem­per­a­ture heat than tra­di­tional boil­ers, it is es­sen­tial that your home is in­su­lated and draught proofed well for the heat­ing sys­tem to be ef­fec­tive.

It could also make the sys­tem cheaper and smaller.

What fuel will you be re­plac­ing?

If you're re­plac­ing an elec­tric, oil or coal heat­ing sys­tem, ground source will save you more on your heat­ing bills. Heat pumps are not usu­ally rec­om­mended for homes on the gas net­work.

What type of heat­ing sys­tem will you use?

Un­der­floor heat­ing sys­tems, larger radiators or low tem­per­a­ture fan con­vec­tors (warm air heat­ing) can per­form bet­ter than stan­dard ra­di­a­tor-based sys­tems be­cause of the lower wa­ter tem­per­a­tures re­quired.

What are the costs of in­stalling?

Costs of in­stalling a typ­i­cal sys­tem range from about £9,000 to £20,000 depend­ing on the size of the house. Grants of about £750 may be avail­able from April next year.

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