Blockage in heated towel rail


29 Nov 2005
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United Kingdom
I've got a heated towel rail which is fitted in parallel with a radiator in the bathroom (the pipework tees off below the radiator flow/return pipes and goes into the towel rail valves). There used to be a blockage somewhere in this, which meant that the top couple of inches never got warm water through. This wasn't an airlock, as I could unscrew the vent valve completely so that the screw came out altogether, and no water came out.

After putting some sludge remover into the heating system, it seems that the blockage has got worse, as the whole towel rail is now cold. (I assume that a load of muck has been freed up from elsewhere and has got into the towl rail and blocked it completely). I tried shutting down the valves on the radiator in order to try to get more water through the towel rail, but the bottom couple of inches next to the flow valve gets luke warm, but that's as good as it gets.

I'm wondering about taking the towel rail off in the hope that I can clear it out, but I'm not sure of the best way to do this. Is it likely that I'll shift anything just by putting a garden hose into one of the valve tails and giving it a good blast of water? The design of the towel rail is a simple 'traditional' style, with two uprights and two vertical bars.

Thanks in advance for any suggestions!
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try putting your hand on the flow pipe before the valve. does it get hot. also when the towel rad was fitted was it shaken out for the crap thats usually inside them
Hi there - yes, the pipe leading to the flow valve gets hot. The valve itself feels hot, but it doesn't go much further.

The rail was already fitted when we moved into the house 3 years ago, although I'd say it's a bit older than that.
My guess is the vent on the towel rad is blocked as a blockage in the feed pipe would result in the rail not working at all.
shut both flow and return valves on the rail and remove the vent pin, stiak a pin or needle in the vent hole and try venting again.
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Excellent! I poked a straightened-out paper clip through the vent valve, and within seconds it was full of piping hot water! (oh yeah - I should have remembered the bit about shutting the valves down first, but I didn't get too wet in the process......).

Many thanks for the advice - it seems obvious now, but it hadn't occurred to me before.

I wonder anyone could oblige with some further advice related to flushing the system out: There's currently a couple of bottles of sludge remover in the system, which has been doing the rounds for about a month, and now needs to come out. The questions I've got about this are:

1. Would you drain off from just one downstairs radiator, or is it better to do it from more than one at the same time?

2. Would it be better to stop the water coming in through the header tank, empty the system out altogether and then flush more water through, or would you just let the water keep going through until the water coming out is clear?

3. I assume it would be a good idea to put an inhibitor in the system afterwards - would 1 litre be sufficient for a system with 9 radiators on?

Thanks in advance for any help - as always, much appreciated.

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