TRV question

[Leoki]

If replacing a TRV on an indirect heating system i am aware you can bung the vent pipe and the cold feed from the F & E to the boiler creating a vacum (so long as there are no micro leaks anywhere in the system).

With regards to a sealed heating system, that fact that it is sealed, can you carry out the same process of replacing a TRV without the need to drain the system because it is a sealed system. Is it this simple or am i overlooking something blindingly obvious ?

 

[Puddle]

yes you can replace valve without draining system on pressurised system,but obviously you will need to let the pressure out first

Some would say you should isolate expansion vessel for best results to stop any dribbles but the danger of isolation valves leaking afterwards could be more of a problem

 

[Leoki]

Puddle - thankyou for time/response.

Release the pressure in the same way as you would if doing it on a vented system, isolate the radiator at both ends the open the TRV slowly to release any excess pressure and it should slowly stop and hold as a vacum ?

 

[Puddle]

do same as vented system,release system presure through system drain cock or boiler drain if one fitted,then close drain and then work on radiator