Single pipe central heating
- Thread starter Graham22
- Start date
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ive got the mistletoe in my back pocket john 
Can i just interject and ask;
is Hailsham's pic of a one pipe and two pipe system correct?
I though one pipe systems went through from rad to rad. His pic clearly shows a pipe that tees off to each rad. If that's the case then surely you could shut off one rad and it wouldn't affect the the others as the water would still flow from the single pipe and tee off into the other respective rads?
I'm only asking in here as i often get confused and just when i thought i understood the difference, i see that pic and all is confusion again.
Hope i'm not hijacking too much. It may even help the op.
is Hailsham's pic of a one pipe and two pipe system correct?
I though one pipe systems went through from rad to rad. His pic clearly shows a pipe that tees off to each rad. If that's the case then surely you could shut off one rad and it wouldn't affect the the others as the water would still flow from the single pipe and tee off into the other respective rads?
I'm only asking in here as i often get confused and just when i thought i understood the difference, i see that pic and all is confusion again.
Hope i'm not hijacking too much. It may even help the op.
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Clearly we need to know more about where the pipes run, if its really is a single pipe, if so if its a convential old style single pipe with one loop with each of the rads of it, or if some one has actaully just linked all of the rads end to end. If its actaully its just a weird/bodged twin pipe, or some hybrid.
Worst case, if it really is just all in one line, into one rad, out in the next, into the next, etc, no bypasses. Then yes, remove all TRVs, and if the last rad is the one you want the most heat out of, depending what order the others are in, you could even replumb at the boiler to reverse the direction.
Daniel
Worst case, if it really is just all in one line, into one rad, out in the next, into the next, etc, no bypasses. Then yes, remove all TRVs, and if the last rad is the one you want the most heat out of, depending what order the others are in, you could even replumb at the boiler to reverse the direction.
Daniel
My diagram shows how it should be done!
Only about 30% of the flow should go through each radiator. You can fit a TRV, specially designed for one-pipe systems, on the connection to the rad.
Thanks mate, appreciate the clarification.
So you need to fit TRV's that have the flow in only on direction? (they have an arrow on them indicating the flow direction don't they?)
Some TRV's can be fitted either end of the rad can't they? (i assume on two pipe systems only?)
So you need to fit TRV's that have the flow in only on direction? (they have an arrow on them indicating the flow direction don't they?)
Some TRV's can be fitted either end of the rad can't they? (i assume on two pipe systems only?)
No, you need to fit TRV's that are suitable for a one pipe system, the nozzle is twice the size.
The flow into the rad is by gravity, unless you fit special tees which Kevplumb and me were on about.
Well, i'm still a little confused by it all, but i don't wish to derail the thread, thanks anyway fellas.
I was just curious as i was reading the thread,
i've since popped over to http://diydata.com/planning/central_heating/pipework.php
and that has helped me in understanding it better.
i've since popped over to http://diydata.com/planning/central_heating/pipework.php
and that has helped me in understanding it better.
do they all do that
I once saw a setup like that BUT the pipes went through a central valve which , in effect diverted the water from that rad to the next - yup , they were all linked one to the next like a daisy chain . Now if it had started life like that and the rads had been changed . The boiler was a Thorn Pacific - anyone remember them Surly it doesn't matter how the pipes connect to the rad?
It's how they connect to the main one flow pipe?
Ie the main pipe on a one pipe system should be a continuous run from boiler throughtout the house and back to the boiler.
Then two separate flow and return pipes tee'd into this one main pipe to and from the rad
So if the pipes are under the floor, it's a bit hard.
The only one pipe system I have seen, had all the pipes surface mounted, so it was easy to see how it worked.
It's how they connect to the main one flow pipe?
Ie the main pipe on a one pipe system should be a continuous run from boiler throughtout the house and back to the boiler.
Then two separate flow and return pipes tee'd into this one main pipe to and from the rad
So if the pipes are under the floor, it's a bit hard.
The only one pipe system I have seen, had all the pipes surface mounted, so it was easy to see how it worked.
Thanks for all the posts. I haven't had the floorboards up myself (it's at my son's house) but the plumber said they were all in one line, and he took the top off all the TRV's as he said if one was closed that would stop the entire system.
I think he checked it out carefully as, in the end he was there a very long time, but kindly did not charge any extra (originally he came in to sort out boiler problem).
So is the general consensus to add another pump &/or reverse plumbing direction at boiler?
Thanks for your help on this - they have a young baby and it is quite cold in his room.
I think he checked it out carefully as, in the end he was there a very long time, but kindly did not charge any extra (originally he came in to sort out boiler problem).
So is the general consensus to add another pump &/or reverse plumbing direction at boiler?
Thanks for your help on this - they have a young baby and it is quite cold in his room.
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