Ground source heat pumps vs air source heat pumps

Author: Cormac Reynolds

As energy bills have seen a relative plateauing out, too much fanfare within the media, many consumers are understandably feeling underwhelmed at the limited savings that are on offer.

After all, 5% discounts are hardly a speck upon the unprecedented price increases for gas and electricity over the past decade and unsurprisingly many have looked increasingly toward renewable energy, and traditional energy alternatives, as an answer. Even with falling gas prices, thanks the emergence of cheaper fuel through fracking and other means, this continues to be the case.

Two forms of home energy that are experiencing particular surges in popularity are ground source heat pumps and air source heat pumps, both of which provide for a seriously cheap way of heating the home, whilst being subject to respected green credentials.

However, as with all forms of natural energy, consumers need to be informed in order to make the right choices; so here we take a look at these two forms of heating the home, going beyond the basics to decipher which of the two, if either, is preferable.

Heat pumps: Setting the scene

Heat pumps, of either sort, have a relatively simple premise. And that is that they draw heat from either the ground or the air and convert it into a fluid that then heats the home. This fluid is processed through the system and compressed, which in turn then heats the liquid up further. The end of the process is where the heat exchanger within the system then transfers the heat from the fluid into the water that travels around your home’s heating system.

How do heat pumps compare to traditional electricity?

Electricity is one of the most expensive ways of heating the home. To put this in to figures consider that one kWh of electricity costs, on average, 0.15, whereas one kWh of gas costs 0.4. Most notably however whilst the typical electric powered system would see one kWh transferred into a single unit of useful heat, either of the pumps we speak of here would transfer the same into 3.5 units of heat. So in summary, these pumps are far, far more efficient as compared to the typical electric based system.

Ground source heat pumps vs air source heat pumps: Comparing the two

The premise of Ground source heat pumps and air source heat pumps operate upon same sciences, however despite this the costs of installing each system are significantly different.

For an air source heat pump, installation costs approximately $7,500 for the average home (although this figure doesn’t include the installation of underfloor heating).

In comparison the installation of a ground source heat pump comes in at around $23,000. This significantly higher figure is, in part, down to the need for bore holes that must be drilled, which can cost as much as $9,000 alone.

Physical requirements

Air source heat pumps operate in many ways like an air conditioning system, coming in at a similar size to commercial conditioning units that you may have seen on the outsides of office blocks. That said the size of these systems do differ, and will depend upon the size of your home and how well insulated your property is. Generally speaking however these units may be a metre tall, a metre wide and run back to the wall by half a metre.

In comparison ground source pumps work through pipes that will be laid within your garden, and they may be either laid horizontally across or vertically down (with the former option being significantly cheaper).

Efficiency

This section has a clear winner, and that is ground source heat pumps.

As ground source heat pumps provide for hot water heating that is particularly effective it naturally ensures that you save all year around, especially during winter when your hot water usage is at its highest.

As well as this ground source heat pumps have lower operating demands as well as temperatures that are more easily regulated, whatever the time of year.

The finances

Both air source and ground source heat pumps benefit from a range of financial subsidises under different Renewable Heat Incentives. However there is a difference between the payments that are provided for each system, with an aim to redress the difference between the installation costs. In both instances it is reasoned that over the course of the scheme that the costs of installation will be covered.

 

Cormac Reynolds

 

Cormac Reynolds writes on a variety of green subjects. He works for groundsun.co.uk and can be contacted on twitter @brightoncormac

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