Hissing Honeywell TRVs

[Alfredo]

I think you will find it still hisses even with new TRVs. There is not a lot to wear out, what you are hearing is a partly closed TRV valve. Someone suggested a by pass. Do you have a by pass radiator (one with no TRV) or a by pass circuit ? I know that many boilers have a built in by pass, but its often a good idea to add another. We do, and it works.

You will always get some noise from a partly close TRV, though it shouldn't be too intrusive.

Alfredo

 

[croydoncorgi]

it might reduce the flow rate but not the pressure, so less water will be going through per minute, but still at the same speed

I think you need to understand the physics of heating systems a bit more, specifically the (very fixed) relationship between pressure and flow rate!

Why not try it. Cost = zero.

 

[Aulus]

I have 2 bypass rads, but - solution in sight - it must be the water.

Today I fitted a rad in the loo. Turned it on, hisses as loud as all the others.