"Adam Topp" wrote in message
m...
Hi,

I have just acquired a heated towel rail, which, when looking at the
spec. is designed apparently for use on a closed system only. Our
system is open vented. What is the difference between a radiator
designed for use on a closed system as opposed to an open one. I
cannot see much difference but I'm now loathe to put it on the system
for fear of what it may do or damage may be done.

Adam,

There are two types of heated towel rail, those for connection to the
central heating radiator circuit and those for connection to the hot water
system (as long as this is circulated by a suitable pump).

The logic for connecting to the hot water system is that you may want your
towels heated even when the heating is off in the summer. Because new water
is going through the hot water system whenever a tap is run, you need a
brass towel rail for connection to that circuit - the new water has lots of
air in it which would rust a steel towel rail.

It sounds like you have a steel towel rail, which is intended for connection
to the central heating radiator circuit. I think that this is what they mean
by a closed system, as the same radiator water circulates all the time, and
apart from leaks it is not replenished. This is not really affacted by
whether there is an open expansion tank on the system or it is a completely
sealed system with a pressure vessel. The expansion tank may allow
marginally more air into the system, but this should be minimal if the
system is working properly. Let's hope it is, because your radiators are all
made out of steel, and they will rust just as quickly as the towel rail!

I'm not 100% certain about this, but 'pretty sure'! Perhaps someone else can
confirm.

Geoff