Geothermic Heating

[Le Chemin]

Hi All,

We, my family and I, bought a large property in Giat 18 months ago. It still needs plenty of work doing to it, but, we are thinking of putting in geothermic heating. I have read a number of articles/web sites on it and understand the basics of it but they never mention a price. I understand that there is a company in Clermont-Ferand who can do the work but just wondered if anyone has experience of this type of heating, how much work was involved, and ofcourse, how expensive it is?

Mike.

[minesthechevy]

Hi Mike

Based on my personal experience, I would suggest you firstly define what you're prepared to sacrifice; your garden or your wallet.....

Basically, you can go down 2 metres (tops) over a very big area (several hundred square metres) for the pipefield, or you can go down vertically. For my 300sqm house, at 650metres altitude, I was looking at three 70metre deep holes - ballpark figure €17K.

Now, let me sweeten the pill - if you have a good flow of running water on your property (eg a healthy stream) you can literally lay your pipe in it - it'll work OK.

Also, if your water table is less than 70 metres below ground, then you'll only need one shaft, and even that only needs to just reach the water table - so you may be lucky and get away with a low cost to the vertical idea.

Be aware that the 'Coefficient of Performance' (which is the ratio of energy in:energy out) drops off markedly at around +3 to zero degrees - and gets worse as the temperature drops. 'Aerothermie' systems are even worse......

Another thing about geothermal that the salemen dont want you to know - There have been unconfirmed reports that the early systems have overcooled the ground surrounding the pipework, and I have been told that Sweden now specifies a minimum distance between separate household installations, possibly over the supercooling effect.

We looked at all the options and eventually settled on cheap and cheerful solar panels to boost water heating.

[giantpanda]

Here you can get free quotes:

devissimo.fr

Yours,

giantpanda

[Le Chemin]

Hey, thanks for the replies.
giantpanda; we will try the link and try getting a quote, thanks.
minesthechevy; why did you go for the solar panels in the end? You said they are "cheap n cheerful". I haven't thought about them, but, thought they were expensive, not only to purchase but for the continued servicing? Where did you purchase your solar panels from? if you don't mind me asking.
Also, are you saying, when you mention 'Coefficient of Performance', that when the temp drops below +3 degs, that the cost to run comes more in line with conventional heating, or that it just isn't as efficient running as it is the rest of the year? (am I saying the same thing there......)
Mike

[minesthechevy]

<<<why did you go for the solar panels in the end?>>>

Well, my other half did not take too kindly to having one third of the garden ripped up; and the €17K was just for the holes, not even the tubes to drop down them. This place is enough of a money pit as it is....

<<< You said they are "cheap n cheerful". I haven't thought about them, but, thought they were expensive, not only to purchase>>>

Solar panels come in two breeds - those which look like, er, solar panels, and those which are solar panels moulded to look like tiles. The difference in price between the two would keep gordon brown's slush fund healthy for weeks ;-)

<<< but for the continued servicing? >>>

Apart from a quick peek to make sure they're still up there and to hose them off, there is no maintenance to them, is there?

<<<Where did you purchase your solar panels from? if you don't mind me asking.>>>

Not at all - the decision will probably be to go for German units, because they are a lot cheaper.

<<<Also, are you saying, when you mention 'Coefficient of Performance', that when the temp drops below +3 degs, that the cost to run comes more in line with conventional heating, or that it just isn't as efficient running as it is the rest of the year? (am I saying the same thing there......)>>>

Yes you are in effect saying the same thing - it is NOT 'free' heat, it needs to be harvested, and that takes an electric pump.

Say you use a 1kW pump, the system will give you 3-4 kW of heat down to 3 degrees, then only 1.5-2 kW ie the returns diminish.

When you start your research, make sure you get CoP figures for ALL temperatures.

For background, we are hedging our bets in all directions; solar panels running underfloor and wall-panel heating as our primary heating, plus wood fires and 'turbines' for when its so cold even alastair darlings smile looks warm. It does get down to minus 15 here even in the recent gentle winters.

[Le Chemin]

Hey, thanks for that. Cheers, Mike