advertisement


Geothermal heat pump domestic heating system?

NeilR

NeilR

pfm Member
We are considering buying a house (in Switzerland) that has a geothermal heat pump heating system.

I am told that there is a borehole drilled into the rock below that is 200m deep and water is circulated and heated by the warmth of the earth and this is used to heat the house. Electricity provides the backup heating/additional water heating.

My question is are these systems any good, i.e. how much energy do you think would be saved? or are we still looking at a significant electricity bill in the winter? It's quite a big house (250m2) so I am worried about huge heating bills.

What about reliability, any particular worries? it seems quite a simple system on the face of it.

Does anybody have experience/knowledge of this kind of setup?
 
There are various types of heat pumps systems (ground source, air source, water source). My Sisters house has an air source heat pump system and it is excellent. The ratio on energy return seems to vary from 1:2 up to 1:4 (I kw in; 2-4 kw out) so much more efficient than using electricity alone for space heating. I am told that ground source or water source are better than air source so your potential system should be good. Downside seems to be maintenance of the heat pump itself but I have no experience of that.
 
My understanding is that these systems work particularly well with underfloor heating as this can use the lower temperature water that heat pumps provide. If the house and heating system were designed with the ground source Heating in mind it should be very effective.

The system should be reliable as it is little more than a industrial refrigerator.
 
I have an Air Source heat pump. Its excellent for anybody off grid I was spending £1800-£2000 a year on LPG I now spend less that £800 and because the heating is on 24/7 you do not have that up and down with the temperature it just stays warm all the time. My mate has a ground Source heat pump and his comments are similar to mine.
 
Obviously, it depends on the system, but I had one in Sweden. Kept me toasty warm when the outside temperature was -15 degrees C.

Stephen
 
When I looked into it capital cost was the main disincentive. C£16k for a four bed house.

You need to run the system at a low temperature to get maximum efficiency so big rads required if using a conventional water based circulation.

Hot water will require additional heat input. Insulating the house properly becomes more important.

The mechanical bits are supposed to be reliable now.

If already installed and it's not being priced in excessively i'd be very happy to buy the house.
 
Lucky you. I'd have it like a shot. As others say the big cost is installation. In addition I'd say that if you have the money for a 250sqm house in Switzerland then you don't need to lose too much sleep about heating the place. Nice problem to have, and all that.
 
Ground source heat is probably the most efficient heat option available to anyone. I am guessing it is used for under-floor heating. The low temperature (compared to a wet or electric radiator) is emanating from the entire floor area, which is huge by comparison to a wall mounted radiator. You leave it running continuously in the Winter as it is not a system to warm up, or cool down quickly. You have a very large thermal mass maintained at a comfortable temperature. The electricity cost is for the electric pump. If you could find a way to drive the pump from solar panels, wind or a water turbine, you would be warm for free!

It is a little bit like driving a room with a back horn loaded Klipschornns, 3W maybe for very loud, compared to running a pair of Devialet Phantoms (who knows - 1Kw or more?). Get same loudness but an entirely different 'feel'. And efficiency.
 
As there seems to be some confusion I think this needs pointing out...

Geothermal systems use the Earth's internal heat directly from natural sources like hot springs, geysers and volcanic hot spots.

Ground source heat pumps are vapour compression refrigeration devices (like air source) that use an underground heat exchanger as a heat source (rather than an external coil and fan). It uses electricity to move heat energy from one place to the other.

Sadly, marketing pricks for heat pump installers/manufacturers seem to have decided that throwing the word geothermal in to their copy is a good idea. It is at best misleading as it is different to the long standing definition of what geothermal energy is, at worst it is grade A bat-spit as at the depths we are talking about the energy probably comes from the sun warming the surface, not the Earth's internal heat; so it would be less dishonest to call it solar!
 
Last edited:
The OP mentioned Heat Pump in the title so I assumed it would be Geothermal coupled to a Heat Pump to extract maximum benefit from the heat source.
 
Thanks all for the responses. very useful - sounds like it is a plus point of the house and not a cause for worry.

I am not exactly sure of the design of the system, all I was told is that warm water from the borehole is used to heat the house. Underfloor heating is used all round. The house was certainly toasty warm when we viewed it, despite being close to freezing outside.

The house itself (known locally in the village as the 'Schlössli') is over 100 years old, but was gutted in a fire in 2005. the current owners rebuilt it from a shell including new roof, internal floors, new windows, so it is like new inside. They obviously took the opportunity to install a good heating system as part of the renovation.
 
Snufkin said:
The OP mentioned Heat Pump in the title so I assumed it would be Geothermal coupled to a Heat Pump to extract maximum benefit from the heat source.
Click to expand...

Not paying attention and off by a factor of 10 :D, at 200m the system the OP is describing will be a GSHP, not Geothermal...previously post edited for accuracy!
 
stevec67 said:
Lucky you. I'd have it like a shot. As others say the big cost is installation. In addition I'd say that if you have the money for a 250sqm house in Switzerland then you don't need to lose too much sleep about heating the place. Nice problem to have, and all that.
Click to expand...

Yes, we are lucky, but we have saved prudently for 25 years and were fortunate to be able to come to Switzerland 6 years ago and both find work. If you look at house prices relative to average earnings, I think Swiss houses are far cheaper than houses in SE England!
 
We have an apartment in central Basel, which has underfloor heating, but it is a new build to Minergie standard. My main concerns would be the quality of insulation on an older building (but it is likely that the renovation you mention has addressed that already), and also the fire safety. When we rented, we had a flat in an older building that had been renovated, but the ceilings between floors were filled with grasses, probably from the upper Rhine wetlands. Not great sound or heat insulation, and they did prove to be a fire risk. Good luck!

The other thing to check is the wiring - the colours used by Swiss electricians do vary, and it's not always clear which is the live wire.
 
We currently rent in Therwil, but house prices are far too high in this area as much as we would like to stay here. We are looking a bit further out in the Jura where houses are a lot cheaper. In fact, I suspect the rather large house that we are thinking about is no more expensive than a flat in central Basel!

I am with you on the insulation and fire safety though, it is a concern but the house has been very well renovated. I don't think corners have been cut but of course it is always possible.
 
Tantris said:
The other thing to check is the wiring - the colours used by Swiss electricians do vary, and it's not always clear which is the live wire
Click to expand...


why is that? I cannot for the life of me understand why in such a well organised country, the electric wiring is a bit of a free for all!
 
NeilR said:
why is that? I cannot for the life of me understand why in such a well organised country, the electric wiring is a bit of a free for all!
Click to expand...

It is nuts, and I don't understand it either! I put all the lighting into our place, and although the earth was obvious, I had to call back the electrician to correctly distinguish the other two wires. We have an impressive circuit breaker box, however.
 
It's perfectly straightforward...yellow and green is PE unless it's very old - then it's yellow and red, blue is neutral except when neutral is yellow then it might be live, red, black and white are permanent lives except when they're switched, and all other colours are switched lives, neutrals or commons :D

*This post does not constitute professional advice and the poster takes no responsibility for the forces of natural selection if you mess with mains voltages without knowing what you're doing!
 
You must log in or register to reply here.


advertisement


Back
Top