Welcome to the forums.

The quick answer is no. Heat pumps can’t be indoors. The air needs to be replaced because once the “heat” has been stripped out only very cold air remains so new air is required for the air source heat pump to remain effective. So they must be outdoors.

As for your GSHP, 100k is astronomically high. On average, with vertical boreholes they should be around 30k.

@editor

Hi Mars,

What you actually stated is not entirely correct, since it is possible to get ASHP's that can be installed indoors, but have to have the intake and discharge air ducted to the outside. Having said that they do tend to be the smaller range of units. On my last project, down at Kent Science Park, the portocabin type offices had such units, but they were A2A type.

Posted by: @iainw

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Don't we all... Hi forum, I've just bought a new house (old build, dates from about 1830 and very hard to insulate, eg no double glazing, with an antique oil fueled boiler) and am looking at renewable options for heating and hot water (to start with). I wanted to go for a ground source, vertical, but the quote (and we've only managed to get one so far) was well over 100k, assuming of course the geology is amenable (we've not test drilled yet). I realise that this pays for itself in the long term, but I may not live that long... The alternatives are horizontal ground source (which is certainly possible, we have the space) or air source. Our local heating person is advising air source, but I don't like the look (on an attractive old house). However, it occured to me that placing the pump inside, ie sourcing the air inside the house, might be an option. I can't really find much online about this (and nothing returned by a search in this forum, so apologies if it's there somewhere and I've missed it), although it does seem this is possible. We have a large, unheated and uninsulated cellar that is open to the outside through what appear to have been ventilation slots in the walls at (outside) ground level (ceiling level in the cellar). So we don't really care if a pump makes it cooler in the cellar. The question is, is this a possible solution, to put an ASHP in the celler, given that we would want heat and hot water? The house is about 330 sqm over three floors with 3.7 m ceilings on the ground floor (lower as you go up), so a lot to heat above head height! Thanks for any advice.

Iain.

Hi Iain, welcome to the forum.

I agree with Mars that 100k does seem rather excessive even for a GSHP. I would suggest that you contact the GSHP association. I think Mars may have the details. What size of heat pump were they offering? What is the heat loss calculation of your poorly insulated property?

To answer your original question, in theory it may be possible to mount an ASHP within a cellar, but either the intake air and/or the discharge air would need to be ducted to the outside. It would also be necessary to ensure that the discharged air cannot enter the intake. Maybe take the intake from the South side and discharge to the North side. The cellar area may need some level of soundproofing.

Probably a greater problem may be convincing an ASHP installer to carry out the work.

I would also suggest trying to improve the level of insulation, unless you have very deep pockets.

Thanks both. First, I should say that I am in France, although I'm guessing the technology is much the same, if not the prices. For the GSHP The driller (is that the term in English?) wants 53k€, of which about 13.5k for the extracting bore and 20.5k for the reject bore, the rest for all the peripheries.

Unfortunately I'm not at home at the moment so don't have the quote for the rest of it to hand at the moment - I'll get it later - but from memory, just over 45k for a large pump (no, don't recall how powerful) and 55k for two smaller ones. The reason of the two smaller ones is that they don't think they can get a single large pump into the celler (which is where it would go). So all up, not far off 110k€, which these days isn't far short of £100k.

I will get all the details since I would very much like some opinions on what's behind this price difference.

As for ASHP, noted, and it's really not my option. perhaps a horizontal ground system.

@iainw, not the knowing the prices of drilling in France it's difficult to comment on whether that's expensive or not, but by UK standards that is very steep indeed. 

You might find this interview with Geoff Ellison useful – they're an established borehole driller in the UK: 

Thanks Mars, will watch. Interestingly all the websearches I try for "how much is a geothermal heat pump?" (which is what the French call it) come up with figures in the 20-30K range, all included (eg https://www.travaux.com/chauffage/guide-des-prix/prix-pompe-a-chaleur-geothermique). So I don't understand why our quote is so high. Unfortunately I can't get another driller to quote, but I'll keep at it.