Reverse Circulation.

[sym]

The upstairs radiators are getting warm when programmer is on hot water only. This has only recently started to happen, I don't think that it's the 3 port valve as the flow outlet to the heating is cold. Surely it's not a piping issue as it's only just started to happen. Any ideas?

 

[nysk2008]

Although you've checked I would further investgate the 3 port possibly letting by first of all

 

[Ermintrude]

Or debris has accumulated and now easier for water to pass rads??

 

[sym]

I have clamped a temperature sensor on the heating outlet of the 3 port valve and another on the return from the radiators, the heated water is definately travelling back up the heating return also the the return pipe on the rads is heating up first.
When the programmer is switched to heating all reverts to normal operation.
Another plumber fitted an expansion vessel at about the time of this problem starting, do you think an airlock or small restriction in the return to the boiler could cause this fault as this would force water up the return(this being the easiest route)???

 

[BLOD]

Can you post a picture of the pipework where the expansion vessel was fitted

 

[sym]

The expansion vessel was a like-for-like replacement on the boiler.

 

[Ermintrude]

Take a picture of pipework by cylinder and valve.

 

[SafeGasInstall]

i think you will save time if you call a local heating engineer to repair it .....

 

[sym]

I am the local heating engineer, I was asking around to make sure that I haven't missed a trick. I did the temp checks to prove that the 3 port valve wasn't at fault and to prove which way the water was travelling i.e finding the easiest route which was back up the radiator return and not back down the the return to the boiler. To me this would indicate an air lock or a blockage.

 

[SafeGasInstall]

Have looked for a bypass under the floor ? Can you confirm hw return is the last one before boiler on primary return ? Is your pump running ok ? What does happed. When you put ch only ? And have all rads down stairs turned off ?