TRV bang

kcopp

What would cause a TRV to bang when the heat is running?
TRV has been in the system for close to 15 yrs... no issues. The system is able to be quiet if the valve is opened up 100%

Alan (California Radiant) Forbes

If no changes have been made to the system, replace the TRV.

GW

Take the TRV head off, and push against the piston-valve with a blunt object. If you can re-create a noise, your flow is probably going backwards.

If there’s no odd noises, I would take the TRV head off and swap it with another radiator somewhere else, see if the noise follows or see if the noise stays

kcopp

The entire TRV or just the head?

GW

You should be able to take the head off pretty easily, it’s usually finger tight or channel locks will loosen it. If you’re really unlucky, you won’t be able to separate the head from the valve. I hate when that happens. So, take the head off, and push against the little piston and see if you can replicate the noise

kcopp

Thanks.
From the description I was wondering if you were suggesting to drain down the system and pull out the entire assembly.

GW

no need to drain. At least for this portion of the experiment

Alan (California Radiant) Forbes

I doubt if it's the head and think that you will have to drain the system and replace the actual valve.

ChrisJ

I might have missed it but what kind of system is this?

kcopp

Hot water. old cast iron radiator. Probably an old converted gravity hot water system.