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Towel rails on one pipe systems

View the thread, titled "Towel rails on one pipe systems" which is posted in UK Plumbers Forums on UK Plumbers Forums.

C

Chewton-red

I have a recently had a new bathroom fitted with a 6' towel rail. The rail has never heated up. Our heating is a one pipe system. I have tried closing down all the other radiators in the system to force the flow, but to no avail. Now the plumber who installed the bathroom tells me that towel rails will not work on a one pipe system.
Is he right, or is he spinning me a line to avoid rectifying the situation?
Any advice will be gratefully received.
Chewton-red.
 
How old is this system ? alot of new items will-not work to well on one pipe systems, towel rails i would have thought would need 22mm connections to stand a chance of working!! :mickey:
 
Hi.
The system is pretty old with a half inch pipe feeding the radiators, although some of the pipework is bigger (possibly 22mm).
 
1) Has the towel rail been bled?
2) Is it a new addition or has it replaced a previously working rad?

A towel rail is just a rad and if one was in the same position and working well, then there is no reason why a towel rail wouldn't work equally well.
 
Some of the towel rail valves are only tiny bores. Should work OK if you fit with a large bore valve and lockshield.
 
The towel rail actually replaces 3 rads. We used to have a separate loo, bathroom & shower room - each with a radiator. The new bathroom incorporates all three knocked into one. We just left the plumbers to get on with it so I've no idea how it was actually plumbed in.
 
Trouble is a lot of "plumbers" don't know about anything other than modern systems and what they did at college.

If you have dinky little fancy chrome valves on your rail thats probably part of the problem. The other part is that the system won't have been balanced properly. Did someone spend several hours going round the property adjusting all the radiator lockshields using thermometers etc after the installation was completed? My guess is they didn't, and if not, it needs doing (after the valves have been changed).

Is the pipe which the towel rail is teed off getting hot (i.e. is water flowing past the rad and missing it out?
 
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Trouble is a lot of "plumbers" don't know about anything other than modern systems and what they did at college.

If you have dinky little fancy chrome valves on your rail thats probably part of the problem. The other part is that the system won't have been balanced properly. Did someone spend several hours going round the property adjusting all the radiator lockshields using thermometers etc after the installation was completed? My guess is they didn't, and if not, it needs doing (after the valves have been changed).

Is the pipe which the towel rail is teed off getting hot (i.e. is water flowing past the rad and missing it out?

I cant actually see where/how the pipework for the towel rail tees off the main pipe (22mm or the imperial equivalent) as its under the floorboards somewhere. I managed to lift a board on the landing and the hot pipe that would appear to be coming from the right direction was indeed hot.
I can only presume that the plumbers linked the pipework correctly when they removed the other rad's.
 
I don't think it's just a matter of balancing as Chewton-Red has turned all other rads off and still gets no heat, which is why I asked if it had been bled. Seems either to be air-locked or blocked somewhere. Do you get any water coming out if you open the bleed valve?
 
Rail has been bled and yes water does come out of the bleed valve.
The plumber who installed it says that the head of water in the rail (6' tall) has too much pressure to allow the water to flow into it. Personally I think this is hogwash as you could asy that about most rad's. Also there are radiators upstairs on the second floor and the hot water flows up there ok.
 
It probably isn't hogwash.
Your 'one pipe' disribution pipe goes upstairs to feed your rads so your statement about rads working upstairs doesn't make any sense really.

As others have said, modern towel rads have a high internal resistance due to their open bar design (and often pretty questionable manufacture with tiny openings in the main risers to feed the horizontal bars). This doesn't matter in a modern two pipe system where a pump forces the water through the rads but a one-pipe system relies on thermal convection to 'encourage' flow through a rad so if the internal restriction is too high it'll just bypass the rad. It's also the wrong shape and has the wrong connections to work effectively as a one pipe rad. There's a good reason that traditional one-pipe systems used big, horizontal low resistance rads and big low resistance pipework.

I'd also imagine that your towel rad is towards the end of the loop which means it is probably way undersized - one pipe systems generally have radiators of increasing size round the circuit to cope with the fact that all the preceding rads have cooled the heating water.

I have seen the last rad on a one-pipe system piped so that it's 'in-line' and becomes part or the 'one-pipe' distribution system but it's a bit of a bodge.

I think your plumber is probably right - it's never going to work (and it's not his fault).

I'd either put a conventional low resistance panel rad in and hope for the best or repipe the house as two pipe and enjoy the benefits of a modern heating system.
 
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You will need a rail with 3/4 (22mm) connections and only a couple of rails, somthing of this sort would be quite expensive !
 
ive come across this thing before, pretty wierd as it just bypassed the radiator. we put a quarter turn lever valve on the pipework, then opened it very slightly forcing the flow to go through the radiator. goodluck
 
As it is a towel rail that "replaces 3 rads" it is newer going to over heat the room so an easy fix is to put a valve between the tees, fit lockshields to the towel rail and force it to be part of the circuit. A bit of a compromise but it's your cheapest and easiest option.
 

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