Assuming the whole system is drained down.
Turn off the circulating pump isolating valves. Disconnect another radiator (as close as possible to mystery pipes.) Close valves on all other radiators Connect a garden hose to one of your mystery pipes. Turn on water and see which pipe it comes out of on disconnected radiator. It will be the same (flow or return) as the one the hose pipe is connected to.
Hi all,
I'm putting in yet another radiator, but in this instance have been unable to ascertain which pipes emerging from a wall are which. Given the physical surroundings it's not possible to trace them back. The rad I'm connecting up will have a plain valve at one side and a thermostatic one on the other. I'm resigned to connecting it up both ways in turn and seeing which works better. Is there a more scientific method, though, and if not, how much difference in temp should I expect between right way and wrong way?
cheers, cd.
Most TRVs allow for fitting on either of the flow or return.
Infra-read thermometer, failing that feel the pipes with your fingers after turning on the rad, the flow pipe will get warm before the return. I think you can put a TRV on the return side without serious effects
Agreed. If the body has an arrow on it, though, you need to send the flow that way.
Most TRVs are multi directional.
Unfortunately, this particular one isn't.
Make a temporary connection between the two exposed ends. Run the boiler for a few minutes and see which pipe gets warm first.
This may be a silly idea, but if the pipes are metal ones can one not just measure the resistance from the nearest known pipe, ie the one which the directions known in, to the end of the cut pipes in turn. I'd have thought it a fair bet the lowest resistance was the closer to the known one. Brian
I have some TRVs on the return - they are supposed to be reversable - but they start fluttering as they close and cause resonation. I intend to rotate them 90 degrees rather than swap ends.
When we moved into our present bungalow we had to move a couple of radiator s, so I took the opportunity to replace a couple of odd radiators which loo ked like they were quite old. Every valve/TRV was replaced exactly as befor e only to find after re-commissioning the system all but one radiator was t he wrong way. However, the system worked OK despite that. It turned out the boiler flow and return were mixed up when it was replaced some 3 months be fore the house was put up for sale. Since then I have corrected the fault b y sorting out the monkey puzzle of pipe work.
Richard
I have a rad in the utility room I've had to disable because of the terrible racket the TRV made by resonation. I never knew the reason. So it could just be that that rad is connected up the wrong way around, then?
Would reducing the flow to the rad on the lock shield side ease this. I have a similar problem with two Mistral TRVs and was wondering.
Definitely, when my new boiler was installed the wrong way round one of the TRVs made a dreadful hammering sound as it tried to close, the vibration was so bad the nut connecting it to the radiator worked loose and started to leak! Once the boiler pipes were switched round the problem disappeared.
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