On 10 Sep, 10:39, DIY-Not wrote:
On Mon, 10 Sep 2007 10:23:17 +0100, "Roger Mills"
wrote:
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
1280 Watts per M^2 (of projected area rather than total surface area) at a
Delta-T [1] of 60 degC. On that basis, your radiator would have an output of
about 645 Watts. You may struggle to get a towel radiator with this sort of
output because they necessarily have far less surface area than a normal
radiator size for size.
[1] Delta-T is the temperature difference between the room and the mean rad
temperature. Your system probably runs at less than 60 degC difference, in
which case the radiator output will be less. If you compare it with another
one which is also rated for a Delta-T of 60degC, it doesn't matter. If you
compare it with one specified at a lower Delta-T, you need to allow for
that. For example, your rad would be worth about 515 Watts rather than 645
at a Delta-T of 50 degC.
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.
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
10 plate heater a bit like this from Screwfix but 75mm wide plates.
http://www.screwfix.com/app/sfd/cat/...79837&ts=22101
I don't know what it's heat output is but it acts well as a towel
drier and room warmer. To back it up there's a pull cord fan heater -
viz
http://www.tlc-direct.co.uk/Main_Ind...Fan_Heaters_3/
which was put in for my wife's benefit only !
Rob