Radiator Output Calculator

Ignite

Hi,
I've been looking at a new radiator for a bedroom we are redecorating.  I've gone on 5 different companies websites and used their online radiator calculators.  All of them give wildly differing results ranging from 271W (925BTU) to 700W (2390BTU) at Delta T50.  All of the sites ask about the room size, type of walls / roof space etc so are working on the same information.  How do I know what is the correct results to use?

Thanks

nofoollikeold

1. All the online calculators use assumptions for the heat loss of the room, some more accurate than others for some factors, others more accurate for different factors.
2. I personally don't trust any of them to be accurate because of the above, and use the CIPHE method manually / via Excel.
3. If in doubt put in the biggest radiator.  You can always turn down an oversized radiator, but you can't turn up an undersized one.
4. Given that the future is likely to be lower temperature heating circuits, oversizing is probably a good option anyway.

FreeBear

nofoollikeold said:

1. All the online calculators use assumptions for the heat loss of the room, some more accurate than others for some factors, others more accurate for different factors.
2. I personally don't trust any of them to be accurate because of the above, and use the CIPHE method manually / via Excel.
3. If in doubt put in the biggest radiator.  You can always turn down an oversized radiator, but you can't turn up an undersized one.
4. Given that the future is likely to be lower temperature heating circuits, oversizing is probably a good option anyway.

Fitting a larger radiator means the room should heat up a bit quicker and/or you can run at a lower flow temperature. A lower flow temp means that your boiler (assuming a condensing one) will run slightly more efficiently.

A 600x600mm Type 21 would be an ideal size based on the output quoted by the OP - 750-800W is slightly above the required 700W, but that won't matter. Reasonably compact too. Fitted on in a small box room (2.4x2.4m with two external walls), and it heats the room up quite nicely.

locky123

If the current radiator size is adequately providing heat then go om stelrad and input the size/style to see the BTU output. If you want a different size and/or more BTU then select different size options and type. https://www.stelrad.com/radiators/standard-steel-radiators/classic-compact/

FreeBear

locky123 said:

If the current radiator size is adequately providing heat then go om stelrad and input the size/style to see the BTU output.

Or this site -> http://www.simplifydiy.com/plumbing-and-heating/radiators/power

Ignite

Thank you all for your replies.  I'm erring on the higher end of the scale for the heat output as I can always turn it down.