Does Geothermal heating really work?

[Angie]

Does anyone have experience of using geothermal heating.  We have received a quotation to have this installed in our new build and although I was expecting it to be roughly "comparable" with a normal boiler and radiators system, the estimate has come out at almost 3 times as much.  Although I am impressed by the savings that can be made (some 75% reduction in electricity costs) we are naturally a little cautious about investing such a large sum of money in something we know very little about. (We spent about £4,000 in the 80s on solar panels for our UK house and frankly they were rubbish!). 

What I really need to know is whether the system will really keep the house warm without the need for back-up heating.  We are going to be using underfloor heating both downstairs and up and will probably have an open fire in the lounge during very cold spells.  I would hate to spend all this money and find that we are having to supplement it as obviously I am hoping to recoup some of this initial large outlay!

Naturally the information we have received with the two quotations are full of praise for the system and claim they "are all we need", are maintenance free and will last for a minimum of 25 years - am I just being sceptical?  Any advice would be much appreciated.

Bevvy

[Nick Trollope]

[quote]Does anyone have experience of using geothermal heating. We have received a quotation to have this installed in our new build and although I was expecting it to be roughly "comparable" with a normal ...[/quote]

I have friends who installed geothermal water heating and they swear by it. 360W of electricity for about 2Kw of heating for the hot water. However, to get this 2Kw, they installed 70M of underground piping - to get 40Kw for a largish CH install, it follows that you would need 1.4Km of piping - I see no reason why the relationship between extracted heat and pipe length should not be linear.

Geothermal heating sould also work backwards - producing "cold", too - as I understand it.

We are fairly up north (22) where the use of geothermal CH is rare (I don't know anyone who uses it!) - it may be for this reason.

We looked at it - and will probably use geothermal water heating soon - I reckon your costs are lower than we were quoted about 2yrs ago.

 

[Angie]

Thanks Nick for your helpful reply.  Our quotation for a 136m2 property is 20,000 euros but this does not include excavation or making good.  Obviously it is a large initial outlay but if we save around 1,000 euros a year, it doesn't sound quite so bad.  I gather electricity prices in France are rather high compared with the UK, although our local company (Powergen) are doing their best to keep up with the French!!

Would appreciate hearing from any other users.

[bejay]

Bevvy

To answer your question will I need additional forms of heating the short answer is should be no but this assumes that the system is correctly designed for your particular situation which of course applies to any heating system. This capacity of the system comes from the size of the house,  where it is,  the standard of insulation etc.  Any heating design engineer worth his salt wiil be able calculate this capacity for any type of heating system.

Solar and geothermal systems ( although I dispute the use of the term in the system I think you descibe. To my mind its just another form of solar heating but I am happy to be corrected on this) are energy efficient and you are doing your bit to save the planet. Only you can decide on how much value you place on such honorable behaviour! 

The real question is  will it be cost effective and the general view seems to be that that manufacturers claims are the best gloss on a very close run contest. Remember you have tried solar heating once before and have formed a clear opinion on its value.

bj

[Ty Korrigan]

Geothermal is truly 'Geo' if you opt for a forage which penetrates 100m into the earth.

My French family and I are renovating a small cob house near Rennes and are obtaining the devis now.

I shall keep you informed...

[Deimos]

I had “the experts” around last month. I discovered my local plumber is ADEME approved and we were talking as I was keen to make better use of renewable energy. So he arranged for a group of experts to come round (think it his first potential system) to do a “technical study” - they even brought a translator for me. And:

Noting that I live in a water mill (in a river valley)

1. Geothermal does not work well when pipes are close to (or in) the water table. You need to watch the water table level, particularly in winter (when it may rise and when you want most out of your system).

2. Aero-thermal (like Geothermal but taking the heat out of the air). Appeared better in my case (due to the water table level), but does not operate well in high humidity (mist, fog, etc.) temperature is not so important. They said that aero-thermal at dry minus 7 deg C will work better that at 0 deg C in mist.

3. Geothermal in a river. Can be done (as I liked the idea). However, they were saying that it needs to be over 1m deep (under water) and that was not possible in my mill pond.

4. Solar (heat rather than electric) was thought best for my hot water system. Seems they will propose a solar heat system with an immersion heater. They said I could expect 100% hot water in summer and 30% from solar in winter. However, they also commented that the electric immersion heater is no more expensive that my existing gas energy so I would still save.

You could also consider a wood boiler (that is a boiler that burns wood and NOT a boiler made of wood). I was discussing possibilities with an architect who specialised in renewable energy (etc.) and he liked these systems though they are not common (he said only a few installations in Sarthe). For my house (400 sq m) he estimated the boiler may cost €20,000 or more (so capital costs are high). There are two types – those that burn pellets and those that burn chips and which type you get is normally determined by the system capacity. I am told they are fairly automated (i.e. you do not need to continually go out and shovel in more fuel) but they do take space, as does the fuel.

Their conclusion about the central heating was that somebody needs to re-calculate the house energy requirement (measure all rooms, wall thickness and materials, window areas, etc.). I actually thought that this was a bit like “we don’t know” and so I’ve asked the plumber to just quote for the hot water system at the moment (also I don’t have vast sums on money to do all thus).

Ian

[bejay]

Ty

At 100m I think its earning the right to be called geothermal energy. I presume there wil be a constant temperature at this depth. As a matter of interest and to save me from doing the work and finding out for myself, do you know what temperatures are found at 100m

bj

[Ty Korrigan]

I shall ask my family for these facts...

[Iceni]

You also need to take into consideration the amount of time that it will take to get a 'payback' on the system. We are unsuitable for most of the systems but have opted for log burners (wood yard 1 km away and we live in a forested area). We have also opted for an oil fired central heating system which will be run just above frost free in the winter as we have smaller winter quarters which we can heat with one logburner, the rest of the place is huge.

As underfloor heating is impossible due to the way the barn is built, we have tried to go for a system that is as ecological as possible and will make a sellable property if we do need to sell (central heating means that the whole area can be used in winter).

When solar tiles are finally of a price that makes them useable in the majority of properties this debate may become moot - perhaps the fact that the US is predicting liquid gas for central heating to be 50% higher this year and oil worse will spur the scientists who are working on this to greater effort - they have been around a long time, just not cost effective or easily available YET.

http://www.pvsolar.com.au/

[Angie]

Thanks to everyone for your very helpful replies.  The system we are hoping to go for is a horizontal loop buried 60 cms under the ground over an area of 400m2.  The promise is it will provide constant hot water from a 300ltr tank, run all the underfloor heating and fuel the cooker and lights saving us an estimated 75% in electricity costs.  I am going to shop around and see if we can get the system installed a bit cheaper as still a little sceptical.  Will let you know how I get on.  Thanks again.

[peterw]

Bevvy are you sure they are going to run the cooker and lights? I though geoTHERMAL was only heat generating? Not electricity generating.

[bejay]

Perhaps some detail would help here. The system bevvy describes is operated by electricity just as his cooker and lighting circuit are. Electrical energy also drives a heatpump which extracts free heat energy from the ground, this is where the savings come from. Technically its a perfectly straightforward process.

The difficulty arises when you try to assess the value of the 75% saving  seventy five percent of what exactly. I presume of the electricity bill you would have had if the house were heated entirely by electricity at full price which is very expensive and always will be and probably no-one would ever do anyway. Coupled with the high cost of installation of the system (you have to dig up large areas of land for the collectors) its going to be a long time before you recoup the outlay when you compare it with the installation and running costs of a standard, say, oil fired system. Of course as energy costs rise the economics will change but its not a straightforward calculation more a leap of faith.

bj

[Babnik]

I think putting in oil fired central heating because it's cheaper now, is extremely short sighted. The price of oil is going one way...and that's up. With a large proportion of France's electricity being generated by nuclear and renewable energy sources, I think that Geothermal is a very good option(Electricity WILL become cheaper than oil in the not too distant future!). Couple it with the fact there is a 40% tax rebate on installation, I have found it be only slightly more expensive to install when compared to conventional central heating. I have gone and seen a system working, and I'm still trying to find disadvantages, but can't really find any.

[Iceni]

But you have to be able to install the ruddy thing and many of us cannot - in the same way that our floors would collapse if we tried to put in underfloor heating (and when we took up the thin layer of concrete that was already there we found rotten beams so it was lucky we did not 'take a chance'. The floor will only take boards - nothing else).

Putting in oil central heating is a last resort for us and we intent to use it just to keep part of the property frost free (summer quarters you know old chap). There have been plenty of systems that could have been very cost effective and working if energy had not been subsidised for so long that we all got used to paying peanuts for using a finite resource - and it is now coming back and biting our bums. The research was not done and is now so expensive that no one wants to pay.

New technology is fine - as long as someone else proves to me that it works and is cost effective. I remember how cheap our hot air central heating furnace was going to be in the 70's - smelly, the downstairs was always cold and it simply did not work.

[Ty Korrigan]

 

 Does any one out there think it is the realms of the Bricolar to install a horizontal Geo thermal system?

I can manage all the ground works and actual fitting of anything, I imagine the tough part is the firing up of the system...

This is where trade protectionism get irritating here... The 'Fockers' won't supply,advise or budge on the issue of self installation.

I pointed out that it is possible in the free world for a man to achieve anything he sets his mind too so why not this...? No answer given...just a gallic shrug. They just won't give us the bits!

[bejay]

Hi Babnik

Don't disagree with what you say but nowhere do I say you should install oil fired central heating because its cheaper today. I just feel  that people should understand these system so that they can make an informed judgement as to whether they are actually getting what they are told they are getting. Just look at the list of heat pump based devices mentioned in Deimos' informing post. Don't tell me there isn't scope for a scam or two amongst that lot.

Not sure I'm as confident as you about the nuclear energy industry though. Tell me why I should be!

bj

 

[Ty Korrigan]

Now then... the problem with burning oil (hydrocarbons) is that we release elements into the atmosphere that have been 'banked' effectively put away/stored.

If we used fuel oil derived from plant matter as in veg oils we are using the existing CO2 in the atmosphere then simply re-releasing it again.

Now then... where is the future for a veg oil burning heating system...?

[Hegs]

>If we used fuel oil derived from plant matter as in veg oils we are using the existing CO2 in the atmosphere then >simply re-releasing it again.

Why not logs? We have a variety of heating systems, that is:

- Wood burning stoves provide a good source of point heat, heat up everywhere upstairs of them, are very cheap to run and look great. Wood comes from 2 miles down the road so I guess pretty eco-friendly. Pain on a cold morning!

- Inherited tanked gas central heating for a little while every day when its cold to equalize the temperature around the house; and all day when it is bloody freezing!

- Cheap plug-in electric convention heaters and oil filled radiators for late nights in the office, heating a single room etc.

[Ty Korrigan]

Hegs you are a beardy weirdy!

Maybe a question of automation and mass... Liquid logs? yes I have heard of pellets but wood is very slow to produce calories as plant naturaly tend to put all the energy into the seeds and this is the reason that annual crops such as rape and maize have such high calorific value.

Is that image one of you or of 'Tim' the enchanter of Mont Python's holy Grail...?

[Deimos]

[quote]Does any one out there think it is the realms of the Bricolar to install a horizontal Geo thermal system? I can manage all the ground works and actual fitting of anything, I imagine the tough part is...[/quote]

There are pre-filled systems available that are DIY installable. However, last time I checked they were not yet approved for France – by which I mean they are no approved for the 40% tax rebate. You can still buy and install them, just can’t get the tax back. Try looking on http://www.greenspot.biz/ (sorry you will have to cut and paste the link) – then look in the Avenir Energie section. This is just an example and I’m sure there are loads of others.

Ian

[Deimos]

[quote]I think putting in oil fired central heating because it's cheaper now, is extremely short sighted. The price of oil is going one way...and that's up. With a large proportion of France's electricity be...[/quote]

Re: the 40%. I think you may find this only applied to the cost of materials (i.e. the pump, pipes, etc.) and would not include installation costs. Also, as it is given as a tax credit, it will only be available to people who pay French income tax.

Ian

[Hegs]

>Is that image one of you or of 'Tim' the enchanter of Mont Python's holy Grail...?

Try Slartibartfast!

I was making the point that if you want a combustible form of plant matter, you don't need to go for liquid bio-fuels as there is already a well-establish version!

[Ty Korrigan]

Slartibartfast! what a hero! I used to use a variation of his ' Ah the late Dent, Arthur Dent' when ever a certain member of staff was ...late... He was the late 'intertesting' Bland... Young Bland had always interesting excuses and was always late...

However... you can't easily go away for even a day without you wood stove going out...

[Fridgeman]

Hi All

As one that works within the industry may I pop in here............. as in all figures and savings quoted by manufacturers etc these are under IDEAL conditions ............. normally these occur once every 3 months on a Thursday and last about 1 hour !!!!!!!! ............ do these systems work ...... yes they do ........... are they cheaper to run ....... yes they are .............. are they expensive to install .......... yes they are .......... do they break down............ yes they do ........... are they easy to repair .... no they are not ( you will need a refrigeration / air-con engineer with knowledge of YOUR system)............ are repairs expensive ........ yes they are ......... is the pay back time as quick as they say ........... very debatable, and in my opinion NO!!........ do I think they are rubbish ............... no I do not ............. IMO they are still in the experimental stage ...... should you be a guinea pig ............. that's up to you ................would I be a guinea pig ..........no I would not ...... so what would I do ......... air to air heat pump ...........  why? ...........well for me a tried and tested system with a reasonable green factor ..... do these systems work ...... yes! you enjoy them in offices & shops .............cheaper to run ......... yes ...... are they expensive to install ........... should not be  ....... do they break down ....... very rare ( some units have 3 year warranty) ...... are they easy to repair ........ any competent engineer should be able to repair .... are repairs expensive ...... could be, but not normally ....... is the pay back time as quick as they say .......... no, but pretty close ..... are they the ideal solution ....... not really but closer than other systems

Other factors..... electricity is getting cheaper to produce .... other fuels are getting more expensive ....... you get the full benefit of cooling in the hot weather, very important to some people.

I' ll get off my soap box now ...... and remember nothing is perfect Not even ME.

 

Love to you all

[Gyn_Paul]

So with an 'air-to-air system' are you talking about a blown hot-air

system to heat a house? Not many of us have the space to accomodate

trunking, or am I barking up the wrong arbre?

paul