Geothermal energy from well

[stan]

For the last couple of years we have heated the house here in France with a woodburning stove in the kitchen and portable electric heaters in the living room, bathroom and 3 bedrooms. The house is pretty well insulated and, apart from a winter burning wood bill of about 1000€ and 8 weekly electric bills of about 200€, the heating situation is not too bad considering the house is 160m2.

During the winter when the air outside is below freezing, we can see quite a bit of steam blowing out of a disused well, about 40 feet from the house. The well is about 25m deep and the water below is about 1m deep in the winter, and about a foot deep in the summer (drained probably by the farmer next door).

I am looking into the possiblity of a heat pump system for heating the house in winter and cooling in the summer, and thinking of the possiblity of "tapping" into this heat from the well.

If possible it would simply be air fan heaters/coolers inside the house as I have already renovated and have no wish to rip things up to install pipes for hot water to radiators etc.

Does anyone have an experience of this type of source energy for their heating?, or point me in the right direction for any advice. At the moment I do not want to contact any artisans for devis until I know that it is possible, or even allowed.

[Théière]

The system I looked at required a considerably deeper bore hole for a vertical pipe. looking at 100-200m deep.

[NickP]

Our neighbours in the Loir et Cher had this system fitted in their house three years ago, firstly is was very very expensive; and although at the time they got a good government grant, I believe the grants are now much reduced. The system seems to work alright and utilised the existing radiators, but then unfortunately our neighbour passed away and didn't leave very much information about how it all worked, he was OK as he was a retired engineer, but with his passing the widow has had quite a few problems and getting anybody to deal with it ain't easy. I believe that their running costs which are now electrical are much lower than the oil system they had before. But as the initial outlay was huge, it probably  depends how young you are as to whether the return is good or not. As to depth of the well, in our gardens the water table is very high as we have Le Loir at the end of our gardens so the water table is only about ten feet down. It appears to be a good system but needs a lot of maintenance, and the hardware needs a lot of space. In my opinion if the high outlay is a long term proposition and you get a good back up service I would go for it.

[John Shelton]

We have a geothermal system with fan coil units for heating and cooling. Neighbours of ours have a well system from the company that supplied ours,  Originally we were intending to use the well that we have (similar to your situation) but we were told that the well had to provide a flow rate of at least 40 litres a minute to supply the heat pump, and it just wasn't up to to the job.  As you know, the well water is pumped out of the well, into the heat pump, which extracts the heat and then the chilled water is sent elsewhere (a land drain or stream for example).  You can't return it to the well since it is chilled and will reduce the temperature of the well and the heat pump will shut down.  Our choice was to bore a new well (expensive in France) or use their geothermal ground loop system, which we opted for instead.  This was much cheaper than we expected and nothing like the horror stories we'd heard about about how much people have paid for geothermal.  I know that you can keep your existing pipework since these systems are suitable for retro-fit as well.  The company we bought from were very helpful and were able to give us plenty of good advice.  I'll pm you their details.

[stan]

Thanks to everyone who responded..your advice has been most helpful. Looking at this project logically, I now rather suspect that Geothermal heating in this way will not be possible.

I am now looking into the possibility of still using "pompe chaleur" technology for heating the house, but using the air/air convertor systems.

One problem I have is that the house has been renovated and re-wired by an artisan who did not think to tell me that all reniovated properties considering electric heating, must have dedicated circuits for each radiator/air fan (correct me if I am wrong re this please !)

This being so, the only way to run new wiring around the house without the use of ugly trunking or ripping through plaster, is to run electric cables from the mains electric circuit box to ouside the house and back in via the stone walls (tuffeau built old farmhouse), which is possible physically, although I am not sure how regulations would dictate this.

Any thoughts or advice kindly appreciated.

[John Shelton]

As I see it, if you want anything other than electric heaters in your rooms the options are radiators, which need pipework, fan-coils (heating and cooling) which need pipework and cables (which you already have), or an air system which doesn't need pipework or cables but does need ducting.  Maybe it's possible to run insulated pipes in your attic space and drop down into the corner of each room to feed a fan-coil or a radiator, but either way you will have some disruption.  You can go round and round in circles wondering what to do for the best, but I think it's worth your while contacting the people who supplied our system (they do ducted air systems too), since we found them very helpful when it came to discussing what we wanted and fit us up with the best arrangement.  At the very least it might help you to dispel some concerns and give you a clearer idea of what you do/don't want to do.

[stan]

[quote user="John Shelton"]As I see it, if you want anything other than electric heaters in your rooms the options are radiators, which need pipework, fan-coils (heating and cooling) which need pipework and cables (which you already have), or an air system which doesn't need pipework or cables but does need ducting.  Maybe it's possible to run insulated pipes in your attic space and drop down into the corner of each room to feed a fan-coil or a radiator, but either way you will have some disruption.  You can go round and round in circles wondering what to do for the best, but I think it's worth your while contacting the people who supplied our system (they do ducted air systems too), since we found them very helpful when it came to discussing what we wanted and fit us up with the best arrangement.  At the very least it might help you to dispel some concerns and give you a clearer idea of what you do/don't want to do.

[/quote]

Thanks again John, I don`t have an attic, so dropping pipework down is not an option. The easiest way round this for me is to have an exterior fan system outside and to run the insulated pipework to feed the "inverteur" type heating/coolling units and electrical wiring, directly through the stonewalls and into the gap between the plasterboard, where I can sort out sockets etc, hence my queries about exterior cabling etc., but I will get in touch with the company whose details you kindly forwarded me. Thanks again.

[Quillan]

Our old electric heaters were run off individual breakers per room. For example some rooms i.e. bedrooms had only one heater running on a suitably rated breaker whilst in the lounge area there were three heaters running off one suitably rated breaker. All the heaters were the same i.e. 1.5kw.

The inverter units we bought come with an ordinary French plug with about 1.5M of cable. This is attached to the indoor unit which has a power and control cable loom (and of course pipes) that go to the outside unit.

In my case I used the existing heater cables to power the new units and changed the breakers (which was the most time consuming and difficult bit actually) for lower rated ones to match the power consumption recommendations of the new units. I could, as shown on the installation instructions, just plugged the inside unit in to any available power socket.

The cables that join the unit are about 5M long with pre made ends so you can't cut them and remake them shorter. You have the benefit of being able to hide the cables inside the wall, something I could not do. Likewise I bought the pre-gassed pipes which are also 5M long and again you could put these inside the wall. Everything came in the box including the insulation tape for wrapping the the pipes. The only extras you will have to buy is a cutter to make the hole between inside and outside (40mm comes to mind but I forget now) and the outside mounting brackets. Everything goes through the 40mm hole, pipes and electrics.

If your going to install them yourself, and it really is quite easy after the first one, I shall give you some tips. In the box will probably be a paper template for drilling all the inside fixing holes and for the big hole through the wall. What I did is made two templates out of some plywood I had laying around. The first template allowed me to drill the holes to mount the brackets which take the inside unit. I used these holes to screw the template to the wall. I then drilled a 10mm hole for where the hole would be drilled to the outside because I had a very long 10mm masonry bit which would go all the way through the wall to the outside thus making a pilot hole. The reason for this is because of the crepe I have outside and the first attempt with the 40mm cutter 'blew' the crepe off the outside wall making a horrible mess. I then changed the temple for another which had  40mm hole cut to take the cutter which lined up perfectly with the smaller pilot hole made earlier. The idea behind this is so that you can drill mainly from the inside out but for the last bit you drill from the outside in thus not damaging the crepe etc.

Basically it took me half a day to fit the first unit and after two I was down to an hour and a half. There was a DVD with the units showing how to install them. If you have a DVD with the ones you buy please watch it first as there is some important information on it that is not always in the instructions. I can't remember the exact figures but I did post them on the forum ages ago. Basically the 'pay back' is quite quick, much quicker than ground source if you install them yourself and the savings on our electricity bill has been around 60% although as I said I can't remember the exact amount.

Before I hit the post button I had a search and found the following old thread which you may find of interest.

http://services.completefrance.com/forums/completefrance/cs/forums/1/1487368/ShowPost.aspx#1487368

 

 

[stan]

Thanks Quillan, just what I wanted, much obliged.