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)

 

[doitmyself]

Try the Myson Heatloss Manager

 

[SimonG]

Length of room x width of room x height of room in feet x (multiplier of 3 for bedrooms or 5 for living area) = rough heat requirements in btu's.

 

[Riley]

There are plenty of apps for if you have a smart phone

 

[Harvest Fields]

There are plenty of apps for if you have a smart phone

I don’t know about you mate. But I find these all give different outputs?

 

[leelister6]

Rough guide: L x W x H in feet, multiply by 4 then stick 20% on (Btu's).I always err on the larger size for rads as you can always turn a bigger radiator down. You just have to be careful not to exceed your boilers ch output

 

[jaz]

thanks for the quick response guys

I tried the myson site but I'm not certain about some of the figures
(The radiator height doesn't seem right and some of the tech info isn't explained)

So I tried the room volume method and got roughly 1500
This is a kitchen and a bit ventilated so what would be the multiplier
would you say? 4 times that value maybe for a kitchen?
(It needs to be comfortable as its used as a second living space)

ps boiler ch value?

 

[townfanjon]

To do it properly can be a drawn out process, as the lads have said above just download an app .

 

[spanner]

Then is it a single or a double rad??
Boiler central heating: What temperature should a house be? Should you turn yours up?

 

[Last Plumber]

What's the:-
Length, Breadth, height?
Is it a solid or wooden floor?
How many outside walls?
What is the wall, e.g. 11 cavity, 18" solid, fully insulated etc
What room is it? e.g. bedroom, lounge, dining room etc.