Radiator/wattage question

[martyc]

Guys,
Just knocked an opening wall between sitting room and kitchen...of course this wall had a radiator either side of it...one for kitchen one for sitting room.
Im hoping to get away with just the one rad now in the sitting room.
The dimensions are as follows.
Kitchen 9'*9' and the sitting room is 13.5'*12'
The longest section now of the new room is 21 feet and the location for the new rad will be @ one end of this 21 foot section.
Firstly will one rad suffice?(would save me digging up concrete floor in kitchen)...and secondly a guesstimate @ wattage i should be looking at.
Cheers,
MArty

 

[muggles]

Need to know the height of the room, how many windows, whether the windows are double or single glazed and whether any of the walls are north-facing. Oh and also what the walls are made of.

You can use one rad but it might be quite big...

 

[tonybhoy]

You need approx 3.5KW for a sitting room to be comfortable at 21 degree C with zero or minus one outside however you will probably need about 4.5KW which is a massive rad-from memory about 1800X700 high DP DC.

Better with two rads if it is going to that big though.

 

[D_Hailsham]

You need approx 3.5KW for a sitting room to be comfortable at 21 degree C with zero or minus one outside however you will probably need about 4.5KW which is a massive rad-from memory about 1800X700 high DP DC.

Do you mean that any sitting room will need 3.5-4.5kW or just the OP's combined sitting room/kitchen? If you mean any sitting room, how do you justify the figures?

Better with two rads if it is going to that big though.

I agree that a room 21 ft long will need more than one radiator, just to prevent unwanted draughts.

 

[tonybhoy]

Do you mean that any sitting room will need 3.5-4.5kW or just the OP's combined sitting room/kitchen? If you mean any sitting room, how do you justify the figures?

.

Typical sitting room/lounge rad size where I live is roughly 3.5KW. Think three bar (3KW) electric fire on in winter in the lounge and you'll not go far wrong

 

[martyc]

Hi guys,
the heigth of the room is 8'4"...there is only one external wall(it is 21 foot long)...2 small windows...40"*40" each approx and there is a doble doors 6 foot wide approx.
All the windows and double doors are double glazed and there are no draughts.
Cheers,
Marty

 

[martyc]

...oh and the extertnal wall is SW facing
Marty

 

[D_Hailsham]

Typical sitting room/lounge rad size where I live is roughly 3.5KW. Think three bar (3KW) electric fire on in winter in the lounge and you'll not go far wrong

It will depend so much on the construction of the house that I don't see how you can be so sure.

My living room/dining room is virtually the same dimensions as the OP's combined kitchen/living room. There is a 2kw rad in the living area and a 1kw in the dining end. These are the original rads put in about 20 years ago.

The house has now been double glazed, cavity filled and loft insulated. The rad requirements for the two rooms are now 1400 watt and 750 watt, total 2150 watts which is 28% less than currently provided.

 

[tonybhoy]

It will depend so much on the construction of the house that I don't see how you can be so sure.

Thirty years of experience for a start

You can always turn a rad down (TRV) with more than enough output but you can't turn a lower output one up to provide more heat,can you?

I live in these houses don't forget and Ireland is much the same as the West of Scotland re weather, probably worse if the OP is in the West of Ireland ,so 4KW and above will be about right.

Would hate to have a cold irate punter giving me a sore ear in January as a result of being spot on with my calcs.

Calcs smalcs

 

[D_Hailsham]

It will depend so much on the construction of the house that I don't see how you can be so sure.

Thirty years of experience for a start

Many years ago I picked up a radiator catalogue in B & Q. It had a formula for working out the size of rad for a room, which went something like this: take the volume of the room in cubic feet multiply by a number (5, I think) and that gave you the rad size in BTU. This "rule" was used by heating engineers for years until it was realised that it was producing results far in excess of the actual requirements, mainly due to improved insulation of houses. New builds now have to be insulated to very high standards, though not as high as in parts of Europe, that "rules", such as that quoted, are no longer acceptable.

You can always turn a rad down (TRV) with more than enough output but you can't turn a lower output one up to provide more heat,can you?

But the owner has spent more money than necessary on radiators, boilers etc, or does that not matter to you, the contractor?

I live in these houses don't forget

So you live in a house, like me and millions of others. But your house is not like mine, neither is it like the OPs; so I don't see the relevance of this comment.

Would hate to have a cold irate punter giving me a sore ear in January as a result of being spot on with my calcs.

Calcs smalcs

If the punter is cold your calcs are wrong.

I can foresee the time when heating engineers will have to produce the calculations for replacement CH systems when they apply for Building Regs approval for the work.

 

[Bambergaspipe]

All a load of bollo***x. measure your wall. see where you want it & tell the plumber to put it there.rads are great these days anyway, they bang the heat out, normally the firm supplying will give you what you need, forget all the rest....it`s B##llshit. 3kw max..& I`m being ridiculous........

 

[martyc]

Cheers Guys...ill be fitting it and doing the calcs myself (as in there was a 2kw in one room and a 1kw in the kitchen so im guessing 3kw should suffice!!)
Really my question is whether i need 1 or 2 rads in this proportion of a room....sounds like i need 2...dont fancy the idea of digging up another bit of floor
BTW there will be a wood burning stove in the same room...but right beside the site for the one rad i was hoping to get awat with.
Marty

 

[tonybhoy]

[
If the punter is cold your calcs are wrong.

I can foresee the time when heating engineers will have to produce the calculations for replacement CH systems when they apply for Building Regs approval for the work.

Ain't going to argue the toss with you here but the cost of a larger rad isn't that much more than a smaller one so why would anyone take the chance on the calcs being right or wrong,only thing that matters is that the punter is happy and a happy punter is a warm punter.

I installed my own (last)heating system using a mears calculator rather than my own instinct and you know what? Some of my rooms were freezing in the winter but I knew they were too small in some of the rroms but I went with the calcs,ended up replacing them for larger ones.

Sixty five degrees for a bedroom or 70 degrees in a lounge ain't that warm in the depths of a Scottish winter no matter what the calcs say

 

[D_Hailsham]

... I installed my own (last)heating system using a mears calculator ....

Sixty five degrees for a bedroom or 70 degrees in a lounge ain't that warm in the depths of a Scottish winter no matter what the calcs say

Mears calculators? Fahrenheit temperatures? That's like using a slide rule and log tables to calculate the trajectory of a space ship

It's a funny thing that a room temperature which feels warm in the summer can feel cold in the winter. There must be a psychological reason for this; something to do with sun and snow?

 

[tonybhoy]

It's a funny thing that a room temperature which feels warm in the summer can feel cold in the winter. There must be a psychological reason for this; something to do with sun and snow?

More to do with living in the dreariest wettest place in the western hemisphere,apart from the south west of Ireland,LOL,I'd say