Closed system open system raditors

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.
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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
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Adam Topp wrote:

The instructions may be not so much about open or vented but rather meaning it has to be used on a circuit rather than in the supply to the HW taps.
On flats in North London built between the wars you will often find that the towel rail is in series with the supply to the HW taps. The radiators are made of brass throughout. This is for flat swith _central_ heating in the true sense of the word. I.e. Industrial boiler(s) supplying heating and HW through out the building.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
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I have always assumed that this only works in systems where the hot water is recirculated. Is that right?
The

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GB wrote:

It can be I guess, but in summer the radator gets hot by the draw off of DHW not by any pumps.
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system
the
that
water is

In our house we circulate the hot water summer and winter, as one or two of the taps are a long and convoluted pipe run from the hot water cylinder. In a block of flats they would _have_ to do that.
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GB wrote:

Sure, the DHW is drawn from a pumped circuit - my point which I did not make clear was that (on the flats i've seen anyway) the towel warmer is not part of that circuit but leads to the HW taps from that circuit.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
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