Have I got a one pipe system ?

[Nevis8]

Yesterday I removed a radiator, each pipe had an inline tap, I switched these to off and removed the radiator.

Today my heating doesn't work - the boiler fires up for a few minutes only, no radiators get warm.

my understanding is that one pipe systems have a by-pass, so taking out a radiator shouldn't have any effect, but maybe here it has. Is this likely ? - CH probably fitted mid 80s, rads have TRVs fitted

 

[JCplumb]

Sounds like a 1 pipe system, with those if you isolate anywhere on the loop pipe all the rads stop working. If you have only isolated the rad and not the main heating pipe then it is possible that it was piped up in a way that means each rad is part of the loop, i.e. the main pipe stops and goes through each rad in turn, but the fact that you have TRVs fitted pretty much rules that out.
It could also mean that the rad you removed is the bypass rad, or the one that is always on and part of the loop, Usually the bathroom one or in the room that has the room stat.
Pictures of what you have turned off may help.

 

[Nevis8]

Thanks JC. The rad I've taken out is not a bathroom rad or in the room with a stat, but it is a long way from the boiler so will be at the end of the loop.

I'm pretty sure that someone fitted the TRVs sometime after the system was installed so it's possible they didn't realise what the system was.

The pioework is under the floorboards so I can't see what's going on, but maybe I'll connect the two pipes together and see if that solves the problem

 

[Ric2013]

My limited understanding and experience of one-pipe systems is that water will flow through the system whether or not radiators are connected as each radiator is in parallel with the one pipe that runs uninterrupted from flow to return.

It doesn't really make sense in my mind to plumb all the radiators in series - you are, in effect, making the installation behave as if it were one single radiator, but it may be that this was once common practice?

What do you mean by an inline tap? Are you saying that there is a valve on the pipe one end of which is connected only to an individual radiator? If so, I can't see how this differs in operation from a standard radiator valve, so I wonder why the installer went for this variation.

 

[jonnyswamp]

We need some pictures to determine what you have

 

[Nevis8]

Not sure if these snaps help, you can see the v old style rad I've taken out, leaving two exposed pipes. These had valves in them so it was a simple job to close them, and remove the rad.

I'm thinking that if I connect them then the system will work again ?

 

[Ric2013]

So the two quarter-turn isolator valves come out of the floor and connect to the radiator top (via TRV) and bottom. The radiator is plumbed in top and bottom same end.

Nothing especially unusual in the above.

I'm thinking you may well be right!

 

[cdodds2004]

sounds like 1 pipe,

two types of 1 pipe,

one were the rads are part of the primary circuit and if you isolate 1 the whole system stops.

the other type is radiator takes both tee's off the same pipe that just loops all the way round back to the boiler, this style can have trvs, both are not great systems as heat in the system is not very well balanced

 

[jonnyswamp]

Temporarily connect between the 2 iso valves and turn on (you could use a 15mm x 15mm comp flexi for this)
If everything works, you have your answer
If it doesn't, it points to something else

 

[AWheating]

your system has trvs? if so a system where turning one rad off stops the flow would not work when any trv shuts off

 

[Ric2013]

Think of the saving in TRVs though... 1 TRV controls the whole house