BTUs and Radiators...

[charliegolf]

Hi all,

I'm doing out a through lounge dining room, and SWMBO has decreed we are having new rads! She fancies chrome. Thing is, the online calculators suggest I need 5000 btu for just the lounge end (4m x 4m). Currently, I have 23 year old stelrad 1200 x 450 single skin rads in each room, and we've never had a problem. I can't believe they were 5000 btu each!

Most of any rads I can find at that size online, are 2000 to 3000 btu.

Any wise ideas? Thanks.

CG

 

[CWHEATING]

Must of got that wrong mate. Just replace it like for like size if you’ve had no issues with the room not being a comfortable temperature.
There is more to take into consideration when calculating rad sizes than just height and length of a room. Windows such as double glazed for example.

 

[charliegolf]

Thanks for that, it's about what I was thinking.

CG

 

[alan333]

I read a thread not long ago regarding heated bathroom towel rails. IIRC the consensus was that there's a big difference in the heat output of chrome versions to white ones.

edit... here's that thread...
https://www.diynot.com/diy/threads/trvs-and-towel-rads.500707/

 

[CWHEATING]

I read a thread not long ago regarding heated bathroom towel rails. IIRC the consensus was that there's a big difference in the heat output of chrome versions to white ones.

The surface temperature of the chrome ones certainly gets much hotter.

 

[fixitflav]

Hi all,

I'm doing out a through lounge dining room, and SWMBO has decreed we are having new rads! She fancies chrome. Thing is, the online calculators suggest I need 5000 btu for just the lounge end (4m x 4m). Currently, I have 23 year old stelrad 1200 x 450 single skin rads in each room, and we've never had a problem. I can't believe they were 5000 btu each!

Most of any rads I can find at that size online, are 2000 to 3000 btu.

Any wise ideas? Thanks.

CG

Sounds like the online calculator gives a generous figure, as others have said. With typical water temperatures water 80° and room 20°C, heat output is about 0.8kW/m^2, which I make 0.86kW or just under 3000BTU/h, much like your figure.

 

[charliegolf]

Thanks Fixit, and others.

 

[D_Hailsham]

With typical water temperatures water 80°

A water temperature of 80°C was typical for cast iron boilers and in pre-condensing days. Modern systems should be designed for temperatures in the 60's so advantage is taken of condensing.

 

[heatservice]

Stelrad quote the btu output at 3095 for their 450 high x 1200 long single panel radiator.

 

[D_Hailsham]

Currently, I have 23 year old stelrad 1200 x 450 single skin rads in each room, and we've never had a problem. I can't believe they were 5000 btu each!

If you mean a rad without any fins on the back, then the output is about 1950 Btu (570W in current terminology); with fins it's 920 W.

You can't trust most online calculators - they have a vested interest in selling large rads! Try http://www.myson.co.uk/hlm/