Radiator sizing

Joined
18 Oct 2006
Messages
1,459
Reaction score
57
Location
Staffordshire
Country
United Kingdom
We have a large room 5m x 4m which has always been a little cool. It has a partial pitched roof with a bedroom over 3/4 of it. Window about 3m2 and 2 outside walls (cavity insulated) and one wall to garage probably insulated. Online calculators show about 6000 btu required. A thermometer is showing room temp at 20 C which is cooler than the rest of the house. The valve is wide open with all the other rads almost closed..... I have been into the roof space and added some more insulation and made sure what was there is properly fitted(no voids or draft pathways).

It has a 1200 x 430 twin modern radiator with two sets of fins, no air in it, no sludge - Toolstation rads 1200x400 are 5000 btu so I am beginning to think that the rad is too small.

As I know what the current rad is delivering would installing a 1400 wide rad improve the temperature? Do I need to worry about the “delta”?
 
Sponsored Links
Hi, my lounge is 4 x 5½ metres, and the type 22 rad is 500 x 1800 mm (approx 9000 BTU) perhaps a little too large.
Could you have a taller rad, as well as a longer one?
As Doogle says a 10% or more larger one is the answer.
I would also check the rad sizes of all your other rads and rooms - if they are all oversized (by say 10%) then your lounge rad needs to be the same ratio. I found that at my daughters house, most rads were 20% oversized, so the replacement rad for a bedroom was scaled accordingly. (Original rad far too small).
 
Height is limited by a window with a low sill, could go wider.

Might get a 450mm Stelrad in but 500 won’t fit.
 
Sponsored Links
I asked on another thread but received no conclusive answer.
Are Stelrad radiators the best as they say?
Are they worth the money for my own house?
 
We have a large room 5m x 4m which has always been a little cool. It has a partial pitched roof with a bedroom over 3/4 of it. Window about 3m2 and 2 outside walls (cavity insulated) and one wall to garage probably insulated. Online calculators show about 6000 btu required. A thermometer is showing room temp at 20 C which is cooler than the rest of the house. The valve is wide open with all the other rads almost closed..... I have been into the roof space and added some more insulation and made sure what was there is properly fitted(no voids or draft pathways).

It has a 1200 x 430 twin modern radiator with two sets of fins, no air in it, no sludge - Toolstation rads 1200x400 are 5000 btu so I am beginning to think that the rad is too small.

As I know what the current rad is delivering would installing a 1400 wide rad improve the temperature? Do I need to worry about the “delta”?
There was a thread on this subject not long ago https://www.diynot.com/diy/posts/5150314/
Might be worth asking Alan 483256 what rads he bought.
 
Getting the insulation sorted helped and saw 20C before changing the radiator - warmer than it has been before.

Stelrad 1600 radiator delivered (eventually) from Screwfix. Tuffnells claimed to have delivered it when they hadn't so got it 2 days late.
To help flow as much as possible it was installed with 15mm elbows on the inlet/outlet instead of 10mm that the builders uses and a 15mm lockshield valve in place of the 10mm. It now has a thermostatic valve (there are still 3 radiators in the house without them) and have seen 21.5C in there with the valve set around 5 so much better. Wife doesn't sit under a blanket any more!

Anyone want a 1200x450 Permo radiator?
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top