bejay
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Posts posted by bejay
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cheminot
My understanding is that heating by electricity will, with any degree of certainty, only be economically favourable in the long term if a house is designed and constructed to achieve that goal. This is unlikely to be the case with an existing house in France.
bj
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It seems te me that heat pump technology only just works in financial terms. In fact in the UK mains gas central heating is cheaper to install and to run than a electrical heat pump system.which makes it a bit of a non-starter for most people. But, of course, the situation is different in France. Consequently there are compomises all down the line. However I am surprised just how quickly temperatures smooth out at quite shallow depths, 60cm does seem a bit shallow but at depths of about 80cm to 1m companies do seem to become quite confident.of its effectiveness.
It is perfectly possible technically to install a totally renewable energy source heating system using a mixture of photovoltaic solar panels small scale wind turbines heatpumps batteries etc but at present the cost is astronomic. My rough calculations seem to suggest a figure of about £30,000 as a minimum.
I can't raise much enthusiasm for air to air systems. They don't call it air-con for nothing!
bj
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It is difficult to describe this process in words but perhaps the simplest way to view it is to imagine that the tiles have been laid first and then the house set down on top of them . As Gay says get long visible runs straight and true and work from these. Also aim to cut all tiles to walls rather than ending up with a too wide and probably tapering band of grouting. Professional tilers do all this without a second thought but it does take a bit of working out if you are not familiar with the process.
If it doesn't work out you could always cover it with laminate flooring!
bj
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Andy. Hi there.
In the meantime I have found out a little more detail. I was quite surprised to discover that ground temperature is really quite constant throught the year from depths as little as 2 m down to about 100 metres giving a range from about 10C- 13C. These temperatures are described as a solar heat store. These are UK figures and it seems reasonable to suppose that they will be higher in more southerly latitudes. I think I am inclined to stick to my original viewpoint. However I am really talking about borehole conditions and you are referring to cave systems which are bound to be more complex.. It may be that air circulation will bring a cave system to an equilibrium temperature even if this is not immediately apparent. We are after all talking about a quite narrow temperature range.
It seems clear why some mines are hotter than might be expected They lie in areas of 'hot rock', rock which is highly fractured which allows the circulation of of water to very great depths (1000's of metres). True industrial scale geothermal energy plants are attempting to reach these sources.
Interesting stuff.
bj
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Rob
A few points to consider
As I understand it you feel that your electricity consumption is too high. This is quite difficult to estimate in a short time but let us assume that you are correct .There is no electrical fault that can mysteriously use up large quantities of electriciy undetectably, something somewhere will need to be very hot for a long time. Which brings us to the water heater. How hot is the water, thermostats fail and people are often not precisely aware of just how hot their domestic hot water is. This actually happened to me many years ago and I wasn't aware of it until an electricity bill something like five times the normal turned up It was at a time when I could barely afford to pay the normal bill and was a real disaster.
If your water is not heated by your oil fired boiler it almost certainly should be.
How old is the boiler, some older devices are I believe very wasteful of fuel. This will need advice from a local heating engineer.
bj
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Andy
Nice to see this thread come to the surface again, if you will excuse the pun.
Also nice to see some numbers. My knowledge extended to the point where I was aware that it is "surprisingly warm down a coalmine" and crucially that this temperature is constant . This is what makes it such an interesting form of alternative energy for heating purposes (and for that matter, cooling ).
My private grumble is the use of the word 'geothermal' for some plastic pipes buried two or three feet below ground level when the temperature of the ground will change seasonally and also of course be at its coldest when you most need heat from it. So what name do you give to true geothermal energy? ( I do understand that not everybody feels the need to worry about such details, this fact has on occasion been pointed out to me by close members of my family).
We still don't know what temperature might be found down a 100m borehole but it seems likely to be a bit more unpredictable than I imagined particularly if water tables are involved. Clearly its complicated down there.
In reference to caves becoming warmer further south, this may occur because the surface temperatures will on average be higher and this will slow down the rate of heat transfer to the surface rather than any direct solar heating effect.
bj
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Sorry just testing something that doesn't seem to be working
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My you do paint a miserable picture of the the creuse. I only know it in the summer months.
I take your point about the DHW circulating pump.
My suggestion was that you could circulate the water through the coil of the chauffeau mixte (thanks for that) from your larger tanks so you still have that heated water. The snag with his system is that it will only be working when the water in the large tanks is hotter than the water in the chauffeau and these occasions will be deeply unpredictable.You could of course send the water directly from the solar panels (which will be hotter more often then the water in the large tanks) through the chauffeau and then divert it through the large tanks when it is cooler. This should be possible with a mixture of C/H diverter valves and imagination.
I persevere with this recirculating principle because it is well used standard practice.
Your 10 m of pipe will hold 1.1 litre of water At 12 l/min your it will be through your tank in 5 seconds when it is flowing.
The mains water will pick up heat when it is stationary but littlle when it is on the move.
You can multiply this up for 100m of pipe but that is a lot of copper.
The conductivity of copper is pretty irrevelant here, you can regard the pipe as thermally transparent, its more to do with volume/surface area ratios, type of flow, laminar or turbulent and the low conductivity of water itself.
This is, of course, why heat exchangers such as car radiator cores have many very narrow and flattened water channels and dozens of fins.
Alternatively!
Forget your storage tanks, build a swimming pool, put a collector pipe circuit in the pool connect it to a heat pump, circulate the pool water through the solar panels. You can extract the heat energy from the pool as you need to. If you overdo the heat extraction in the winter you might even get a bit of skating in, that is if it stops raining on you.
Shouldn't cost much!
bj
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Hi there
Thermal conductivity of copper = 380 W/m/degK but I dont think it will help you much. I feel that the heat take up by the fast flowing mains water will be too small to be of much value, neither the surface area nor the temperature gradient is great enough. But do the sums and prove me wrong!
My I suggest the following alternative solution to your situation.
To avoid the problem of hot taps running cold, run the hot water from a single large Chauffeau in a pumped recirculating loop and tap off hot water where you nned to, rather like a ring main. The circuit would need to be well insulated.
To use the solar heated water get a chauffeau with a coil in it (its got a name which I can't remember as I write) and pump the heated water through the coil, again using a recirculating system. You will need a device to switch off this pump when the water in your solar tanks is cooler than the water in your hot storage tank. These are obtainable.
bj
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Steve
There is certainly provision in the Consuel system to inspect partial renovations of existing systems. Have you confirmed that EDF will actually relocate your incomers or that they will accept the new position of your tableau. It seems to me far from certain that they will automatically carry out this work.
bj.
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One question: if using a UK electrician (even if following French regs) how do you get a certificate of conformity for the work if an artisan isnt employed. Would this not affect insurance and the abilty to resell?
Mike
My understanding is that it doesn't matter who does the work . It is inspected independently by the consuel and if it is done right it will get the certificate.
bj
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Do make sure that the dull basic stuff is done. The first essential to good environmental design is good insulation. It isn't easy to get the best possible levels of insulation in an existing building but you have the best chance during a renovation program. and it will certainly be worth an extra cost.
You might consider installing the pipework for underfloor heating if floors are being relaid. This system works well with geothermal/heat pump technology and would be very difficult to install at a later date.
Direct solar heating is also very effective, this of course takes the form of some sort of conservatory but it does need to be designed to achieve this heating function.
With insulation and solar heating it is perfectly possible to heat a house very economically by electricity.
bj
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Quillan. What you describe in such interesting detail would clearly provide a very worthwhile electricity supply if there were no other supply available (actually I did wonder at for a time if I had missed the point about our fantasy watermill and that there was indeed no electricity but it seems there is) but mains power it isn't. I do feel that to take such a direction would be more a political decision than a technical solution. Also I just can't bring myself to believe that an ancient waterwheel is going to give the more or less continuous running that would be essential to your system. I still stand by my opinion that you get what you can out of the system cheaply or do the job properly.which means a new wheel.
Interestingly it seems that the costs for new installation start at about 5000 euros per kW which includes installation and, crucially, grid connection and if used about half and half for personal use and grid supply, then costs can be recovered in about a decade. Goodness knows what the details are but a useful 10kW supply is not a ridiculous proposition when one considers what private individuals do spend on property renovation these days.
What an interesting topic.
bj
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Quillan
I can't see much of a conflict between the two aims. If Jan can get some electricity out of her watermill then its consequence-free energy and if it can be done cheaply then so much the better. But enough already.
On a slightly different tack if an indoor heated swimming pool is important then a possible direction is a geothermal system using the river as the energy source. But once again this is down to local expertise and detailed information.
bj
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Negative, not at all. Useful and highly informative more like but I was rather amused by the number of people that can involve themselves in such a private project. Perhaps I should learn to use emoticons (Nah, too old).
But there is a rather dreary bottom line to this alternative energy and energy conservation stuff and this is that the most cost effective procedure is to reduce your energy consumption (or carbon footprint!).This requires passive processes such as high levels of insulation and direct solar energy etc. Specially developed eco-houses have spectacularly low energy requirements and although they do contain hi- tec devices much of their efficiency comes from good technical design..
Just think of the energy you have saved for future generations by not having a heavy turbine shipped all the way from Canada.I bet it makes you feel warm all over.
bj
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I think that the original posters may have their answer. Quillan is up to £5000 for some of the bits and Deimos has imposed the full weight of French bureaucracy on the project. Coupled with the fact that to be anything like a modern electricity supply the wheel would have to run 24/365, it just isn't a practical proposition.
I have to agree with le visiteur, Machinemart in the UK will be only too pleased to sell you a 5kV alternator for about £250 this would be fun to play with and might just give you some useful heat
Perhaps we should remind ourselves just why there are so many abandoned/derelict water mills in France.
bj
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Jan.
To my mind many of these alternative energy projects need to be a DIY/ home experimenter challenge if they are to make sense financially at the moment. Now I personally cannot imagine any better fun on this planet than spending some months messing about with a mill wheel and an alternator but I have to accept that this may not appeal to everyone's taste. If you were to 'get in a company' to carry out this work it is going to be expensive. You don't say but does your mill wheel actually work reliably? Without doubt though it is possible to get a worthwhile amount of electricity from an industrial water mill, they are powerful devices.
Ron in the Aveyron
This business of feeding electricity back to the grid has puzzled me for some time (but not enough to get me to find an actual answer), Certainly big (container size) diesel generator sets can be synchronised to the grid system but one respectable alternative energy site I looked at talked about simply fitting an import-export meter and informing your electricity supplier.This was however in connection with a wind powered micro generator and I have assumed that the input is so tiny that the grid can just cope with it and its not much more than a PR exercise. Looks like I'm going to have to find out!
bj
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Just a bit of emphasis really. Whem Bannon says a damp mix he really does mean just barely damp.
Secondly I think you will find that it absolutely essential that you use some suitable bonding agent on the concrete or scarify the surface with an angle grinder or even do both. Otherwise your screed just will not stick.
bj
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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
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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
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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
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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
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Ah TU. After all your trenchant posts over the years about the true nature of France I was hugely amused (and perhaps concerned) about your having absolutely nothing to get annoyed or agitated about. Nothing deeper than that I'm afraid.
bj
Heating. Is it worth changing?
in Finding/Owning French Property
Posted
Cheminot
Yes it did come out a bit cryptic didn't it
What I was trying to say is that some very highly energy efficient homes require very little energy input and since you need electricity anyway you you may as well use it for the small amount of heat required. Some of the concepts involved are unusual, going towards bizarre. No normal or traditional construction techniques come near these efficiencies.
Which is a long winded way of saying that electricity is an expensive way of heating a normally constructed house which you know already and is not the question you are asking!
Actually you will have the critical information you require to work out a pretty accurate analysis of costs involved. One years worth of electricity bills will tell you exactly how much energy in kWh you have used to run your house. This has to be matched by any other system you care to choose and then it just a matter of arithmetic. Which is what Albert is saying.
But this is of course based on current energy costs.
I think it is safe to assume that oil will become more expensive but then so will electricity even in France where nuclear power is so important. Electricity is a marketable commodity and its price will be determined by market forces.
I'm afraid there just is not a simple answer to the question you pose.
bj