Howto calculate radiator size for room

[jaz]

How do I calculate the correct radiator size to heat a room?
There must be a formula somewhere even if its only rule of thumb ?

Our current radiator is taking 4-5 hours to heat the room up to about 20C
This seems excessive to me.
The radiator does get hot and has been bled - no cold patches on it.
(although we do have issues with the boiler this is a long standing problem from installation)

 

[Last Plumber]

Did the OP switch off?

 

[jtsplumbing]

Would help if he told us the size of his room and size of currant rad, baffles me why some people get so involved with complicated formulas and calculations just for a radiator, chaps who have been doing this long enough will know by just looking at the room, if rad is slightly oversized so what, there is a proven way to get over this , its called turning down the valve, and most people can do this without calling a engineer, things are to over complicated just no need for half of this BS.

 

[Last Plumber]

Would help if he told us the size of his room and size of currant rad, baffles me why some people get so involved with complicated formulas and calculations just for a radiator, chaps who have been doing this long enough will know by just looking at the room, if rad is slightly oversized so what, there is a proven way to get over this , its called turning down the valve, and most people can do this without calling a engineer, things are to over complicated just no need for half of this BS.

If he gave the sizes and info I asked for in an earlier post, I would work it out and tell him what output I would recommend. I thought it might be a help.

 

[Last Plumber]

things are to over complicated just no need

I would tend to agree with that.

It is one of those long winded calculations which is very methodical and precise. The result however, can still be inaccurate due to all the other factors involved, which are seldom taken into account or cannot be measured.

 

[SimonG]

Better looking at it than for it.