Air Source v Ground Source Heat Pumps

[EcclesCake]

Has any one looked in to either of these systems or even better have first hand experience.

I'd be interested to know your opinions.

[jomifl]

I've just bought 4 units on reduction for £1100 the lot in France. Hope to install this spring in time for the summer. Can you wait that long?

[jomifl]

The price for a ground source heat pump system would have been about £15000 and would have involved a lot of work installing ductwork/pipework. I decided to go for individual units for each room as they would be independant of one another so the whole system couldn't fail simutaneously. They can also be installed piecemeal or relocated according to need.I'm not sure if they are prone to icing up in cold foggy weather but we have electric heaters as backup anyway and they wouldn't be called upon very often. Steep learning curve coming up. :-)

[Clanad]

As mentioned, the ground source heat pumps are quite expensive, due to the installation in the ground. Here in the U.S. they can be placed down drilled wells (maybe 100 feet deep) or in a trench system, but regardless it gets expensive fast. Thing is, once they're installed they are extremely cheap to operate. All that's needed is a cirulation pump driven by a small electric motor. Here in the western U.S. we have an air to air heat pump and it works very well down to about 25 or 30 degrees (F). Below that one needs a back-up source of heat.
The unit sets outside, of course, and is a scroll compressor unit and is fairly quiet, but if I were to do it again, I'd move away from under a bedroom window. It cycles on and off dependant on demand from the furnace air handler. It never freezes up, since it has a sensor for tha tpurpose and goes through a defrost cycle if required.
Here, we get a tax credit for the energy savings. By the way, it also does airconditioning duties in the summer and it's even better at that...

[buildersmate]

I looked at GSHP about 8 years ago and baulked at the cost of about £15k-£20k. Costs are have reduced since then. The issue then was that you needed a fair bit of land area to put the trenches but now more systems drill down - as Clanad mentions. Clearly things are further advanced there then in the UK. ASHP didn't seem to exist 8 years ago.

They do provide near to free energy (just the small cost of running the electric motor). I don't understand why all the focus in the UK on PV installations that look so hideous stuck up on the roof tiles.

[jomifl]

That's reassuring clanad, The units that I bought were such a good deal that I had to make a snap decision before they sold out. I will bear in mind your observations re. siting of the compressor. Having read buildersmate's post(thanks) I realise that we couldn't have ground source heat as we have rock not far below our garden and probably not enough surface area too.

[EcclesCake]

Thanks guys. Jomifl, where did you buy from in France, is it something you can get from Merlin or Msr Le Bric (or whatever the big DIY stores are called!)

Having been quoted around £15k for GSHP we would make a saving longterm taking into account our age and not intending to move from this house.

A colleague recently mentioned that they had GSHP and if they knew then what they knew now they would have gone air source.

I thought I would canvas opinions to see if other concurred...or not.

[jomifl]

Hi Eccles I got mine from Weldom which is (along with Castorama I believe) a subsidiary of B&Q. I got them cheap because the were being pushed as air conditioners(coolers) for the summer heat and these were remaining stock. Most of the big French DIY chains sell them at some time, you can check on their websites to see if they stock them. In the SW. of France Castorama, Mr. Bricolage and Weldom are prevalent, I know there is a Leroy Merlin in Toulouse, but none around me near Agen, Montauban. I believe there is a more expensive version which is already charged with coolant and has valved connectors so that you can poke the pipes through a hole in the wall and connect up. I imagine that a little coolant is lost every time you do this but it is probably not significant. Mine will have to be charged by an a/c 'expert' (they are all expert in France).

[Clanad]

One other bit of information re: ground source heat pumps... thing is they are placed in an area deep enough in the well (differs in all areas) where the temperature is a constant 55 to 65 degrees F. In the winter, they will warm a house but the fluid from the ground source passes through an air handler and is then ciruclated in the house and it never has the nice warm feeling near the register one usually expects. It also runs (the air handler) almost constantly, but, again is only a smallish electric motor. Some systems incorporate an electric warming grid to help warm the air, to which, I think defeats the entire purpose of the GSHP...