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House Renovations
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 04/03/2007, 17:44
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Gluestick
 
Joined on 22/03/2006
UK and Nord Pas de Calais
Posts 2,342
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Re: Boiler heating hot water or not?
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You cannot beat Heures Creuse for water heating, by either oil or gas.
If you really want to copper your bet, ask your plumber to quote you for a bi-fuel ballon, which can be heated either by the boiler or electricity. (Simply, it has a second dedicated calorifier - heating coil - inside, run from a domestic hot water circuit from the boiler).
There is no real downside problem in shutting off central heating for the Summer, provided, of course, it is fully protected with anti-corrosion fluid.
Firing up a central heating boiler merely to provide domestic hot water is extremely expensive and inefficient. Firstly, the system has to overcome the latent heat requirement of the boiler casing, the static water and etc.
Personally, I would stick with a dedicated boiler for heating: and a cheap rate ballon for hot water.
One final point: the heat output of your boiler will be predicated by various factors, which include the volumetric capacity of the rooms; the number and surface area of windows (and the attendant heat loss); the level of insulation of the rooms (and the attendant heat loss); how many levels the house is on, as heat rises; and the ambient temperature you want for each room. For example, living rooms are normally kept at circa 24-5 degrees and bedrooms 18-20 degrees.
Finally, the radiator size is critical as is their placement: rad size is predicated by the total heat output required to raise and maintain each room at the desired temperature, allowing for continuous heat loss.
It is critical to work out the demand potential, maximum. A larger boiler than maximum is always a good idea as the boiler is then not working flat out to meet the requirement.
In my experience, French plumbers are not very good at this!
Worth checking.
"Yes, but that apart, Mrs Lincoln, did you enjoy the play?"
Gluestick
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04/03/2007, 17:54
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powerdesal
Joined on 07/01/2006
Sharjah U.A.E
Posts 2,017
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Re: Boiler heating hot water or not?
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As Gluestick says, a larger boiler than max demand but.......not too much larger, especially if condensing. See comment about part load etc.
The primary factor is, to paraphrase TB Insulation, insulation, insulation.
There is absolutely no point in pumping in heat that is going to go to waste.
The maths of designing a properly sized system are not that difficult, time absorbing perhaps and quite repetitive but not difficult (unless you dont have a calculator).
Steve
Sharjah + 50 (in France)
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Roll on death.....Demob is too far away.
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04/03/2007, 19:22
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Chrissie
Joined on 23/08/2004
southern Tarn
Posts 558
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Re: Boiler heating hot water or not?
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quote"It should be noted that condensing boilers only operate in 'condensing mode' at full load or thereabouts, not at low / part load. Hence, in summer, with just DHW not CH+DHW it will not be in condensing mode and hence any perceived efficiency increase will not be there."end quote
Now that is something I'd never heard of (why would I?) Another nail in the coffin of a dual system. My gut feeling all along has been to stick with an electric ballon, and it looks like this is what we will do.
Funnily enough, I am fairly happy with the way they have all calculated the boiler size required. Each set came with proper measuring equipment and there was a lot of discussion of window location and double glazing etc - our house is pretty well insulated, thank heavens. The old radiators are not going to be replaced or moved in a hurry, but they were installed by a (wealthy) chauffagiste and apparently this was well done. There was also discussion about future plans etc. My only "problem" has been this surfeit of bright ideas and desire to fit new technology for which, on a different budget, I would be all in favour!
Many thanks to those who replied so helpfully
Chrissie (81)
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24/03/2007, 6:36
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powerdesal
Joined on 07/01/2006
Sharjah U.A.E
Posts 2,017
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Re: Boiler heating hot water or not?
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Yes, analogous to the uk system. Its a ballon with a water / water heating coil for when your boiler is running and also an electrical heating element which you use (during summer) when your CH boiler is shut down / not required. The electrical heating element supply can be on heures creuse if its available to you. Its just left electrically isolated during winter CH time.
Steve
Sharjah + 50 (in France)
...........................................................................
Roll on death.....Demob is too far away.
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24/03/2007, 9:10
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powerdesal
Joined on 07/01/2006
Sharjah U.A.E
Posts 2,017
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Re: Boiler heating hot water or not?
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ErnieY,
I am pretty certain that the UK type system in totally illegal in France, I am sure that someone else here can confirm that. Why would you want to do it anyway? The ballon is the hot water store, as it is in the UK.
Steve
Sharjah + 50 (in France)
...........................................................................
Roll on death.....Demob is too far away.
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24/03/2007, 10:36
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ErnieY
Joined on 05/12/2006
Nr Prayssac (Lot)
Posts 2,945
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Re: Boiler heating hot water or not?
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A ballon is indeed a hot water store but in my system the one which was there was purely electric and not heated from the boiler at all. This would be OK for the summer but not really acceptable otherwise.
A new boiler would be far more efficient and quieter than my ancient monster although of course one would expect a new replacement French one to be also.
Maybe the way to go is have a new ballon fitted which is fed from the boiler because storage, by whatever means, is what I need to overcome a lot of the innefficiencies.
I think I'll have a word with the local chuffage engineer who has been maintaining the system for the previous owner.
Cheers
My doctor said one drink per day, I can live with that !
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24/03/2007, 11:10
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Monika
Joined on 23/08/2004
Dorset/Suisse Normande/Switzerland
Posts 621
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Re: Boiler heating hot water or not?
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How would we know if we are on Heures Creuse?
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24/03/2007, 11:26
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Cassis
Joined on 25/12/2005
Here and there
Posts 6,411
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Re: Boiler heating hot water or not?
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Heures Creuses vary - they are 8 hours per day. Ours are something like 2.00am to 8am and 12.30 to 14.30 but other people will have other regimes.
EDF TARIFFS
You have to opt for Heures Creuses - most people do because if you have hot water heating it generally works out cheaper, especially if you have other appliances on timers (départ différé) so you can run washing machines, tumble driers, dishwashers etc. during the cheap period.
It will be shown on your last bill if you are on Heures Creuses.
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France Forum » Building and Re... » House Renovatio... » FAQ - Oil Heating, Hot water production and plumbing “funnies” in France
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