underfloor heating

[Cendrillon]

Try Acova radiators which we were told are more efficient than night storage. We have two of these and they are excellent, we also have woodburning stoves.

[Théière]

[quote user="Pat76"]

" effective at temperatures above 5 degrees" which seems a bit odd, Pat

[/quote]

Why odd? it's much easier to manufacture a unit that doesn't use - deg compared to + deg. The Scandinavians use them and they aren't far off the arctic circle [:)]

[Pat76]

I said "odd" because I thought the whole point was to use these heaters when it's cold!  I clearly have missed something, but I'm happy to try to learn. (notice the word "try", but I will do my best) If the temperature drops below 5degrees, as it does in winter, will the air units work?

Thanks for the name of the heaters, Cendrillon, I will look at them.

Pat

[Cendrillon]

Pat 76

Acova radiators are so easy to controle, they are electric but are filled with a type of gel that retains the heat. With night storage the disadvantage is that you need to plan ahead.

[CollyC]

I am considering putting in underfloor heating when we convert our cave. With insulated walls I am expecting it to be warmer in the summer and cooler in the winter, and so need less energy to regulate.

It occurred to me that the fosse septique is a heat source, both from hot water which we put into it as waste, and from bacterial action. From what I can see on the web it is around 5degrees warmer than surrounding ground. I am wondering if anyone has tried using the fosse with the geothermal system, putting the heat exchange pipes into the fosse tank. It would be easy to install.

[Théière]

Your'e taking the P*ss now [:)] well the energy from at least

[Quillan]

Using the Brico Depot website as a reference for the units I will try and keep it simple.

There are two types of 'Clim' units, standard and DC Inverter. Both give the same result but work differently. The standard type simply turns the external compressor and fan on and off when the room temperature is reached. When you start the compressor and fan from a stopped position it will burn more power to come up to speed. They also work down to -7 deg external temperature. The other unit, DC Inverter, costs more money because it is 'high tech' and rather than keep turning the pump and fan on and off it can vary the speed which makes it much more economical to use hence the better COP number and they also work down to -15 deg outside air temp. However the more you pay and the bigger the brand the better performance and the lower the outside temperature they will work at. Some units work down to -35 deg or even lower and as pointed out they are 'the source' of heating in many Scandinavian countries these days.

If you look on the Brico Depot website they also do a version that heats and cools water which is used as a 'preheater' for a boiler raising the temperature of the water prior to it entering the boiler to be heated further before being sent round the central heating system. You can used such a device with either a oil or gas fired boiler. So whats the point I hear you ask, well it's actually quite simple and I will try to explain. Normally when the boiler starts from cold you have to heat the water from about 5 to 8 deg to around 70+ deg that means you have to burn X amount of gas/oil to raise the temperature from between 65 and 62 deg. If you could 'preheat' the water to say 50 deg you would only have to raise the temperature 20 deg so you would burn less oil/gas. The unit shown on their website burns far less energy to get the water from 5 to 50 deg than the amount of oil/gas you would usually use, how true that is I don't know but it does save you quite a bit of money, some claim around 70% but I am not so sure, I think a more reasonable figure is around 40% saving heating water by this method. As oil and gas prices go up and electricity prices go up at a far lesser rate this saving will get bigger and bigger.

You also have to take in to account that the more you spend the better the performance (COP) and the hotter the water. If you have around 20K euros to spend then Sweco claim a COP of 4.3 (that means for every 1kw of electricity you get 4.3kw of heat or cold) and can heat water to 80 deg so you wouldn't need any other boiler and is ideal for underfloor heating.

It's a big subject to get in to but can save you a lot of money if running costs are one of your main concerns especially with the price of oil and gas going up and will probably increase even further. France, as we know relies mainly on nuclear power so perhaps in the future electricity may become the cheapest form of heating. All these units are also eligible for government subsidies if professionally installed in your primary residence and you complete a French tax form every year.

Just to reiterate I have kept this all very simple before anyone starts' picking 'holes' and that if you are interested do some research and, as always, ask a professional.

Personally we heat with electricity and had rather expensive radiators that came with the house. I have been replacing these with reversible DC Inverter clim units and have seen quite a drop in my electricity bills by about 30%. The only 'temptation' is to use them in the summer when we never had clim before which will of course offset what we saved in the winter. We managed before without them in the summer so we just have to use a bit of self discipline and not get tempted to use them when its really hot.

The other thing we have noticed is that they dehumidify the air as well which makes for a much more 'comfortable' form of heating.

The negative side is that on the old radiator system we had timers to control when the heating goes on and off in different parts of the house, this does not work with these units from Brico Depot. The best you can do is by using the remote control that comes with the units is to tell the unit to switch off after X hours and/or to come back on after Y hours and it only does it for one cycle. Fortunately for me I have an old (about 15 years old now) Philips Pronto Universal programmable remote which I have written a program for so it makes it simpler to use (Mrs Q is no technophobe so it needs to be simple), you just type in the time you want the unit to start, it does the maths and sends the right command string to the units. So when you use it to switch the unit off at night (or whenever) it automatically sends it the right amount of hours for the units to come on automatically at 07:00 in the morning irregardless of what time you turn it off. It's a very expensive remote control unit designed for X10 home automation which I had back in the UK and cost about £400 at the time. It was sitting around in the 'junk box' for six years and has now got a new lease of life. There are remote control units around (and much cheaper) that can be used to do this but I have yet to buy and try one.

[Pat76]

Thank you for taking so much time to give me such a comprehensive reply.

Pat

[Quillan]

No problem. I actually spent quite a bit of time looking in to this before 'taking the plunge' and installing one unit to experiment with. Installation the first time takes some time, about four or five hours because it's a learning cycle. Once the first was installed and providing you have an adjacent power socket next to the internal unit I can drill the hole for the pipes, mount the external brackets and internal bracket, connect the pipes and 'bandage' them in under two hours, it really is that simple and there is very little mess or 'making good'. There was a guy around on the forum called UlsterRugby1999, don't know what happened to him, but he installed the same system for all the heating in his house and his electricity bill was almost halved (he had electric night storage heaters before I believe). I gather he was very pleased with the results, or so I am told, I know I am with mine. As I said, if you are interested, do your research, look around on the Internet, go to a specialist for advice, you don't have to buy from them but they can tell you how it all works and what unit capacity you may need for each room etc.

[tonyv]

I have had ground-source geothermal heating installed in my1960's chalet in Ariège, and am absolutely delighted with it. The only drawback from my point of view was the installation cost, 30k € all found. I don't really expect to recoup that, but the luxury of having a fully-automatic system, without having to shovel fuel or order gas/oil (assuming it remains available long-term) was for me the clincher. I have experience of acquaintances' air-sourced heat pump systems, and without exception, they were extremely noisy and the evaporators tended to ice up in cold weather. This was a few years ago, and the technology has probably improved.

The system feeds underfloor heating downstairs, and radiators upstairs. This winter we have had outside temperatures down to -12C, the central heating was quite up to the job of maintaining a very comfortable living environment; typically 20-22C. The system is rated for -20C exterior temps. In fact, the downstairs heating is so effective, that the thermostatically controlled upstairs radiators, maintained at 18C, hardly ever come on. The temperature of the water for the heating from the single-stage heat pump reaches about 50C, a bit lower than a conventional boiler-based system, but the high-efficiency radiators seem quite happy with this. The underfloor temperature typically sits at about 20-25C, which makes for nice warm feet. Mrs V, who has circulation problems in her feet, muchly appreciates this!

One drawback is that it is not very controllable; because of the thermal inertia of the great slab of concrete under the floor, it takes about 12 hours to heat up, or cool down. The electronics does its best, but can only react to what is happening outside. Thus, if the outside temperature suddenly drops significantly, it can feel a bit chilly until the underfloor heating compensates. However, this is very rare.

We have not yet had a complete winter with the system, so I can't yet testify to its efficiency, but it certainly beats the hell out of the previous system; wall mounted radiant panels, plus an open fire in the living room.

Please, don't believe all the negative hearsay about this type of heating, I'm sure there are some poorly designed/installed systems about, and it does need to be done professionally, but despite all the upheaval, I don't regret for one minute that I've had this system installed.

[Quillan]

I agree with regards to noise although I hardly notice mine but I can't deny there is a noise even if it is very low and in the background but then the noise is outside and with the windows closed you don't hear it. The thing with the DC Inverter systems is they are a lot less noisy mainly because they slow down and speed where as the 'standard' ones stop and start and the initial noise on the start up is quite noisy, think of a refrigerator when that starts and that initial noise it makes for a few seconds.

Most of the units do have a automatic system for de-icing and where you put the outside part is quite important as it explains in the instructions to minimise this. So far we have not had a problem that we have ever noticed.

I would install a ground source pump but the truth is our house is not suitable and the cost of installation is frightening. It's not just a simple thing of digging up the garden and laying the pipe inside the house, most houses have to be redecorated, doors might need to be trimmed and possibly new skirting fitted, OK if you are doing a total renovation or building from scratch. Retro fitting a DC Inverter system is so much easier to do and as I said very little making good afterwards. If I were building from scratch then I would definitely look at ground source pumps. I would also like, as I am sure would Mrs Q, the feeling of walking around on a warmish floor instead of cold tiles.

[Noisette]

I'm a (NOT) 'rich guinea-pig'[:D]  As I had to have a new system from scratch anyway, opted for geothermal wet underfloor heating.  The (single-storey) house was very well insulated, which makes a big difference to the efficiency.   Just come through second winter and wouldn't choose any other form of heating, although as remarked above, some form of back-up would be needed in the coldest weather or to cater for power-cuts. The system also provides for a 300l ballon which is supplemented on cheap-rate electricity. Can't quantify 'savings' because no idea what the electricity bill would have been without the system.

The layout of the pipework takes into account major fixtures and fittings, so these areas aren't heated unnecessarily. The only drawbacks I found were the laughable guarantee of 2 years (negotiated to 3, but still pitiful considering the outlay) and the lack of urgency on the part of the SAV, once the final bill was paid.  But then, this is France!

P.S.  Friends with air/air have had a lot of problems with the convertors breaking down, and the house feels coldddd.

 

[Quillan]

[quote user="Tabitha"]

P.S.  Friends with air/air have had a lot of problems with the convertors breaking down, and the house feels coldddd.

[/quote]

Well perhaps they were installed badly. My oldest is just over three years old and works fine and we have had no problems, no gas loss etc. As for cold, well we are 'toasty' here. The one comment you made which I could not agree more with is that it is absolutely critical you have excellent insulation and decent double glazing but then that's the same whatever system you use.

[Noisette]

Could be, Quillan....the friends experienced the same drawback re. getting the Co back to do repairs, even under guarantee.

And yes, of course the better the insulation, the more effective any source of heat. For sheer, all-over, comfortable, work-free heating, though, GT takes some beating.  Be interesting to compare notes in 5 years time[;-)]