Hydro phonic (noisy) rads with bi directional TRV’s

[RobertC]

Just had a new Potterton combi boiler installed and had the existing radiators single flow TRV’s replaced with bi directional TRV’s (one rad left without a TRV as per norm). When the heating reaches a specific setting one of the rads emits a vibrating hydro phonic noise which can be stopped by moving the TRV setting a fraction. However it returns or reappears on a different rad. I have had some success by turning the TRV settings higher and lowering the boiler temp but this is only a fudge and I am looking for a permanent fix. The plumber has no suggestions as he has only experienced this problem when single flow TRV’s are fitted to a new boiler.

 

[dontknowitall]

Try turning the lockshield a little instead.

 

[RobertC]

I assume I only turn the lockshield of the specific radiator when it is making the noise. At one end of my radiators underneath a plastic cover there is a thin vertical square sided brass pipe protruding through 2 brass nuts, is this the lockshield that needs turning?

 

[dontknowitall]

That's the bit - just a 1/4 turn might be enough. Don't force it too much though as they snap off quite easily.

 

[RobertC]

Thanks for the info, I am waiting for the noise to return before trying it. However since turning the boiler temp down and turning the rads temp up the noise has not yet returned. Is this having the same effect as turning the lockshield and would the noise return if I just reduced the rad settings?

 

[dontknowitall]

Not really. The hole in the lockshield is quite small and the noise is the water being forced through. Nothing to do with heat really (although I suppose there'll be a slight expansion in the metal with the hot water). If you reduced the rad settings (do you mean the TRV?) then this might cure the problem (similar to the lockshield hole).

For the sake of finding a spanner and turning the lockshield 1/4 turn ...!!

 

[Inverness]

hello. ive always used danfoss bi directional trvs which ever is the flow you turn round the grey arrow. this time round ive purchased from plumbfix bi directional trvs but they dont have any arrow like danfoss do. can someone please advise me on this type of trv. they were only £5.99 from screwfix and highly reviews. i just want to try them out.

 

[ShaunCorbs]

hello. ive always used danfoss bi directional trvs which ever is the flow you turn round the grey arrow. this time round ive purchased from plumbfix bi directional trvs but they dont have any arrow like danfoss do. can someone please advise me on this type of trv. they were only £5.99 from screwfix and highly reviews. i just want to try them out.

turn the valve to the flow

 

[Inverness]

It's not that type of bi directional valve trv.