Calculating BTUs from radiator size

On Mon, 10 Sep 2007 09:00:47 +0100 someone who may be DIY-Not wrote this:-

Look up the catalogue for any manufacturer and you should find a similar sized and arranged radiator. Look up the nominal output in kW and you have a figure.

You will probably find you need a very large towel drier to provide an equivalent output.

It is generally best to separate heating the room from drying towels.

It is better not to use BTUs at all. This is an old unit of measurement, with Watts being the thing to use to avoid getting mixing of units and consequent errors.

The approach is to look at radiator manufacturer web sites for radiators that look as close as possible to yours. Most important is to look for the number of panels and whether or not there are fins since these make the most difference to output. You hould be able to determine a figure in Watts.

Armed with that, you can identify a towel radiator. However, this will be challenging, since this is quite a large radiator that you have. Towel radiators don't have much output anyway and it will be insulated with towels.

Not really feasible as it depends on many factors - eg a modern radiator is likely to be much more efficient than an older but similar-sized radiator. Better to calculate the requirements from first principles.

David

I've just been through an exercise of re-calculating my heat losses and estimating the output of my radiators in order to do a sanity check on my system. Most of my radiators are single or double panel unfinned ones, which are not too common these days - so not easy to find current catalogues of similar ones for the purpose of finding the heat output. I have, however, got some historical information from when I installed a system in my previous house in about 1970, and have converted that from BTU/Hr into Watts.

The rule of thumb which I have been using for single panel unfinned rads is

Thanks Roger, this is very useful. My rads are 20+ years old, unfinned, so probably not as efficient as modern designs.. It is possible to get a towel rad with this sort of output but with adding a bit on try and compensate a bit for the insulation of the towels I'm looking at a rad of about 1500mm x 600mm. This is for a white one, can't find a chromed one near big enough. At this size it's probably going to dominate the room too much, so maybe time for a rethink on the project.

================================== Cheap and cheerful - quite effective:

It doesn't appear to be available in designer chrome ??

=================================== Try 'googling'. They are available in (designer)chrome - I've got three, but I've had them quite a long time so can't give you a source.

Cic.

You don't state the size of the bathroom/showerroom you've got which would help us. My bathroom is near enough 2m x 4 and is heated by one

Rob

My bathroom is 2.3m x 3.2m with one outside wall, double glazed, and plenty of roof insulation. So do you find you need to use the fan heater much?

On Mon, 10 Sep 2007 10:39:13 +0100 someone who may be DIY-Not wrote this:-

Is there space to fit a small water filled towel rail. These can be fed off the central heating and provided with an electric element for use when the heating is not turned on.

Alternately use solar water heating and in the summer use a little of the hot water for the towel rail.

Note that SS bathroom rads have a much higher output than chrome plated ones.

If your bath is steel you could hide a radiator underneath (and possibly in contact with) the bath. Robert

They do - I recently checked this point.

However, this is still small in comparison with a panel radiator especially if covered in towels.

Assume the output of the towel rail is zero, which it pretty much is when it's got towels on it. The rating published is with no covering, which is not how towel rails are used. Thus you probably don't want to get rid of your radiator when you add a towel rail.

If you've just splashed out on an expensive designer towel rad the last thing you want to do is cover it up with towels. ! Robert