Central Heating - One Pipe System

James29 · 2 Aug 2006

Hi - Just had 4 new modern radiators installed downstairs. Previously, all radiators in the house were hot. Now, the upstairs ones still get hot as before but only 2 of the four downstairs do - seemingly at random. We have a one-pipe system apparently and the plumber (who fitted the new radiators) says only solution now is to install a two-pipe system throughout the entire house and has quoted me 3 days work for this. Plumber did try blocking off radiators upstairs (which worked to some extent but not a solution) plus slowing the pump down, turning boiler on full, checking boiler pressure, etc. None of these had any real effect in making all downstairs radiators hot.
Any advice gratefully received - we paid for the new radiators from my wife's redundancy and cant really afford the extra cost of converting to a two-pipe system at present but we're stuck with radiators that wont heat up!!
Many thanks.

Bamber gaspipe · 2 Aug 2006

The problem with a one pipe system is because the first rad passes it`s cooler water to the next one & so on, the rads at the end of the heating circuit will be very much cooler than the ones at the beginning.Another disadvantage is water is only pumped around the main flow pipe & not through each individual rad, these are only heated by convection currents. I would suggest that very careful balancing would solve your problem.

James29 · 2 Aug 2006

Thanks for that. Im very grateful indeed.
When you say balancing do you mean varying (and I apologise for the non-technical descriptions)....

1. the thermostatic valves on the right hand side of each radiator.
2. the valve at the left of each radiator that controls the flow of water.
3. pump speed (I assume this should be low to allow more convection)

Another thing I should have mentioned is that the more radiators we turn off/turn down via the thermostatic valves, the less frequently the boiler fires, whereas I would have expected the boiler to continue firing
And also the "input" pipe to the cool radiators are very hot indeed, even though the radiator itself is cold.

Bamber gaspipe · 2 Aug 2006

Go to `sticky topics` at the Forum index, (Plumbing & heating) section, Bahco has posted how to balance rads there. Thermostatic valves are used to open & close the hot supply as the room requires heat, if you close them manually, they will turn off your boiler.

doitall · 2 Aug 2006

James, I bet the plumber has installed them wrong, used the wrong valves etc.

Email me (in my profile) and we should be able to work it out.

psssst forget balancing it will make no difference.

plumbing321 · 2 Aug 2006

one pipe ring mains are quite an old fashioned system in a normal domestic home these days, but basically the idea is to get the water in the ring curculating nice & hot & then it drifts through the rads via convection. It may well be the "ring " could be "sludged up "a little or perhaps even the circulating pump could be a little tired, try adding some central heating cleanser to the system (providing it`s an indirect system )& give it a run for a few days then flush it out. Balancing could also help.

micky p · 2 Aug 2006

i reckon he has installed them wrong. I still have a one pipe system in my girl friends house. When i installed a new radiator on to it, i used swept tees to branch into the pipework. These tees are very much differnt to the normal yorkshire / endfeed tees. They are very hard to come by as well. What thses tees do is force the water to flow up the branch of the tee and into the radiator.
then again i have known them to work on yorkshire tees before today. Also balancing might solve the problem as well.

Other reason could be the pump may of packed in. If the rads get hot upstairs but not down this can be the case. As upstairs rads may be working on gravity.

doitall · 2 Aug 2006

James29 said:
1. the thermostatic valves on the right hand side of each radiator.
2. the valve at the left of each radiator that controls the flow of water.
3. pump speed (I assume this should be low to allow more convection)

Another thing I should have mentioned is that the more radiators we turn off/turn down via the thermostatic valves, the less frequently the boiler fires, whereas I would have expected the boiler to continue firing
And also the "input" pipe to the cool radiators are very hot indeed, even though the radiator itself is cold.

gordon bennett

1- Thermostatic valves on return, Wrong.
2- Thermostatic valves should be of the gravity type.
3- The lockshield should be full on.
4- The pump speed is unimportant at this time, there is no return from the radiator.

Balancing and playing silly buggers will not resolve the issues, so don't waste your time.

Bamber gaspipe · 2 Aug 2006

Micky p & plumbing 321, balancing will make no difference.. WHY?..because DIA has just SAID SO... although I have just checked with R.D. Treloar & he seems to think that balancing a one pipe system is essential...

doitall · 2 Aug 2006

Bamber gaspipe said:
Micky p & plumbing 321, balancing will make no difference.. WHY?..because DIA has just SAID SO... although I have just checked with R.D. Treloar & he seems to think that balancing a one pipe system is essential...

Give Treloar a quick call and ask him what the point of trying to balance the system is. until the system has been installed correctly.

Typical 10 week plumber that hasn't a clue how or why things work.

Bamber gaspipe · 2 Aug 2006

Calm down DIA, we all know the point about the trv`s being on the wrong side was missed, just threw in the Treloar bit to wind you up.. no need to have a heart attack

doitall · 2 Aug 2006

Bamber gaspipe said:
Calm down DIA, we all know the point about the trv`s being on the wrong side was missed, just threw in the Treloar bit to wind you up.. no need to have a heart attack

Missed the bit about gravity thermostatic valves as well I expect.

Bamber gaspipe · 2 Aug 2006

Gravity type T.R.V as in full flow valve, I know the difference...what`s your problem, it was missed & you were right..the post was not read properly..no need to be such a self righteous berk about it...I`m an 11 week plumber by the way..For your information DIA, I am a fully qualified NVQ Level 3 plumber..& registered Corgi Gas engineer, these days I concentrate more on the Gas side..you`ll have to excuse me if I sometimes get a little forgetful on all things plumbing..but any questions regarding Domestic plumbing that you would like to ask feel free mate..

doitall · 2 Aug 2006

Bamber gaspipe said:
Gravity type T.R.V as in full flow valve, I know the difference...what`s your problem, it was missed & you were right..the post was not read properly..no need to be such a self righteous berk about it...I`m an 11 week plumber by the way..

my problem

The OP has had work done possibly by a 10 week plumber( not a reference to you) who now wants another 400 quid to put right his cook-up.

Then we get a load of stupid advice about balancing systems, blah,blah and then you think it's funny hahaha, well I don't, 400 quid is a lot of money to some people.

Nige F · 2 Aug 2006

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Central Heating - One Pipe System

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