Howto calculate radiator size for room

[doitmyself]

how do you think the manufacturer prepares his catalogue, if not from known kW/sq.m? And the catalogue would be based on specified flow and return (and possibly room) temperatures.

I have yet to see a manufacturer's catalogue which was based on known kW/sq.m. They manufacture rad in four different types (P1, K1, P+ and K2) to standard heights and standard lengths. The catalogue tells you the output and you are left to choose the rad which is nearest (higher output) to your requirement.

Of course the data is based on specific flow, return and room temperatures. If it wasn't, the rads would not meet the standards laid down by BS EN 442.

 

[jonnyswamp]

Kinell, just chuck a 5ft double on the wall
Or see post 3
Forget the p1ssing contest above

 

[fixitflav]

I have yet to see a manufacturer's catalogue which was based on known kW/sq.m. They manufacture rad in four different types (P1, K1, P+ and K2) to standard heights and standard lengths. The catalogue tells you the output and you are left to choose the rad which is nearest (higher output) to your requirement.

Of course the data is based on specific flow, return and room temperatures. If it wasn't, the rads would not meet the standards laid down by BS EN 442.

Of course it's based on kW/sq.m. The manufacturer may not state it explicitly, but there's no other way of doing it.
You can easily work out the area from the published dimensions. Divide the published kW by that to get kW/sq.m.
I looked at Screwfix, and one example is single rad 1.2m x 0.6m, rated 1.231kW. That's 1.44sq.m, giving 0.85kW/sq.m, in good agreement with what I said earlier.
I still say nobody else answered the 2nd part of the original question - having estimated the required heat, how to get some idea whether his existing radiator is adequately sized. He could have looked in a catalogue, equally and probably easier, he could have used the data I posted.

 

[Harvest Fields]

Of course it's based on kW/sq.m. The manufacturer may not state it explicitly, but there's no other way of doing it.
You can easily work out the area from the published dimensions. Divide the published kW by that to get kW/sq.m.
I looked at Screwfix, and one example is single rad 1.2m x 0.6m, rated 1.231kW. That's 1.44sq.m, giving 0.85kW/sq.m, in good agreement with what I said earlier.
I still say nobody else answered the 2nd part of the original question - having estimated the required heat, how to get some idea whether his existing radiator is adequately sized. He could have looked in a catalogue, equally and probably easier, he could have used the data I posted.

Yawn...

 

[fixitflav]

Kinell, just chuck a 5ft double on the wall
Or see post 3
Forget the p1ssing contest above

What makes you think he wants to fit a new rad? Perhaps the existing one is a 5ft double.
He wants to check whether his existing one is up to the job, and presumably take it from there.

 

[Plumbagain.]

Some plumbers can judge the size exactly without any calcs.

 

[jonnyswamp]

What makes you think he wants to fit a new rad? Perhaps the existing one is a 5ft double.
He wants to check whether his existing one is up to the job, and presumably take it from there.

If it's taking 5 hrs to heat a room, it's obviously not

 

[jonnyswamp]

Some plumbers can judge the size exactly without any calcs.

That's exactly how we used to do it
Always worked OK but not scientific enough apparently

 

[doitmyself]

Of course it's based on kW/sq.m. The manufacturer may not state it explicitly, but there's no other way of doing it.

If kW/sq.m. is such an important parameter when sizing radiators, why don't the manufacturers provide this information?

If I need 1.75kW to heat a room and the space available is 2 metres long, I can easily select a suitable radiator from a catalogue without needing to know the kW/sq.m.

 

[fixitflav]

If kW/sq.m. is such an important parameter when sizing radiators, why don't the manufacturers provide this information?

If I need 1.75kW to heat a room and the space available is 2 metres long, I can easily select a suitable radiator from a catalogue without needing to know the kW/sq.m.

Why should they? Manufacturers don't usually release technical information. But they must have it as there's no other way of sizing a rad, as I've said.
I was just trying to help the OP to deal with his problem. I've explained and answered your comments several times but you don't appear to understand.

Of course there are other approaches. ​

I unsubscribe from this discussion.