central heating

[Mutiara]

Hi everyone,

Hubby wants to install central heating to our holiday home in France and has asked me to post a  question here; Is there a simple way of calculating radiator sizes for each room (in watts) ? Rooms are well insulated and he wants to buy everything in France probably at leroy Merline.

 

 

[jxedwards]

Is this any help?

 

John

 

http://www.deals4homes.co.uk/heating/heatforroom.htm

[Deimos]

Many years ago I thought about DIY’ing Central Heating in my house where I was living in the UK. I purchased a book that went through the calculations.

Not impossible to work out but too involved to go through here. You measure the rooms, work out heat losses through walls, floors, etc. (there are loss indexes for different materials, different thicknesses, etc.) which then gives you the radiator output required (in my book it was all in BTUs). Also seem to remember it depends on what temperature you want to be able to maintain inside and what temperatures you will experience outside.

I did not actually do it myself in the end as I was working full time and seemed quite a lot of work.

Remember you will need a professional to install the boiler (or do the gas or fuel).

(Above from memory as it was agest ago I was looking at doing this).

Ian

[powerdesal]

Try      www.plumbingpages.com or www.diydata.com

Regards

[La Guerriere]

Very basic rule of thumb

100 watts / sq metre of floor area or 40 watts / cubic metre habitable space. This is for properly insulated rooms.

Also look at www.acova.fr which has an on-line ready reckoner

[tj]

Hi

Years ago when I first did calculations for central heating they were very precise, cost being the main factor.

Nowadays, people demand higher temperatures than were / are considered normal, 20/ 21 for living rooms, 17/18 for bedrooms etc, with materials being relatively cheap your biggest consideration is to have enough output, if you follow the guide below you won't go far wrong.

An average house: assuming 8 ft or 2.7 ceiling height, roof insulation and double glazed windows. 

Length x width of room x 110watts          eg  5m x 4m = 20m x 110watts per sq meter = radiator with output 2200 watts 

Add 15% for 3 m ceiling

Add 15 % for bathroom radiator.

Minus 10% for hallway and non room spaces.

Fit thermostatic valves to all radiators in bedrooms, toilets and the bathroom, and a room stat in the living area.( there are other factors involved such as rate of air change etc, but in general, the smaller rooms in your house heat up quicker than your living space, but without control they will continue their output untill the living space room stat reaches its temperature ) 

Buy long and low double panel rads where you can, double convector types are shorter if space is at a premium. Place under windows ideally, in large rooms, or long and narrow rooms for example put a radiator at both ends to spread the heat input evenly.

hope this helped

Tim, Saintes

 

 

  

[Dave&Olive]

hi

            ok found some old college books of mine , this is a rough guide and is based on uk weather.

 40... 50.. 60... ...        x 40 is for hallways and passages ... x 50 for bedrooms and kichens and x 60 for living rooms ...

      so say a 4mt x 5mt x3mt high living room = 60 m3 ...... x 60 =3600 watts

but you can then add your 10%`s and 15% `s for further north , french windows no....the list is endless

    just a rough guide for info

               dave

the sums work out nearly the same as the last post....

[Mutiara]

Thank you for all your much appreciated replies which have been passed on to hubby. From all the different suggestions above, we have worked out that we could be anywhere from 2500 watts up to about 5800 watts for our lounge which is 5m x 5m x 2.8m high. Quite a huge descrepancy !!

Since it is my job to do the calculations, I am now even more confused. The Leroy Merline man said allow 100w per m2 of floor area but after reading some of the above replies, this seems a bit low ?

I realise it does depend on a number of factors concerning each room, but which such varying results, we now don't know wht to do. Hubby suggested we go for the larger size rads and then have thermostatic radiator valves to keep the temp low?

Thanks again,

Melanie.

 

 

I

[Alcazar]

That's what I did here in the UK when I replaced two very small rads in our lounge with larger ones. The local builder's merchants had a strange "size-needed" calculator that seemed to be made of about 3 concentric card circles with figures on them. He arrived at a figure of 18000BTU for my room, so I went with two 10,500 BTU rads and TRVs. No probs so far. He asked me all manner of things like wall material, whether we had cavity infill, size of windows, single or double glazed, as well as size of room and which way it faced.

Just ensure that your boiler can handle the heat requiremnet of all the rads fully on, before choosing. They will all be on first thing in the morning.....

Alcazar