Thermostatic shower

[The Real JLC]

My thermostatic shower makes a loud screeching sound as the hot water starts to flow through. I think it's because there is a large difference between the hot and cold water pressures. If I installed a PRV in the cold water supply before the shower would this solve the problem? Does a PRV reduce the amount of cold water flow and hence risk turning the shower from a good flow to a trickle?

Any advice gratefully received. Thanks James.

 

[Paulus]

:welcome2: has this recently started or has it been happening since the shower was installed?

 

[The Real JLC]

:welcome2: has this recently started or has it been happening since the shower was installed?

Its Done it pretty much since day 1. I reckon after about two weeks it started.

 

[Paulus]

If it was due to an imbalance in supplies I would have expected the problem to be obvious when it was installed. If it is a recent installation you should get the plumber back to look at it. If not I reckon it's worth taking the valve out and checking that one or both of the filters on the feeds are not partially blocked as a first base for diagnosis.

It may be that debris in the pipes from the installation has found it's way into the filters.

 

[The Real JLC]

Thanks. I'll give that a try. If it still appears to be an Imbalance issue, what do you think about the PRV idea? Would it help? Would it reduce the shower to a trickle?

 

[Paulus]

Where do the hot and cold feeds come from?

 

[mountainman]

If your hot supply is gravity and your cold is mains then a PRV is unlikely to be of much use. IMO

 

[The Real JLC]

The hot comes from an unvented tank on the floor above the shower (townhouse 3 levels) and the cold is mains, and quite powerful!

 

[mountainman]

Ideally the cold supply to the property should come off of the unvented cylinder feed after the pressure reducing valve.
You could fit a PRV on the cold supply and attempt to match the pressures which may help.

 

[PlumbBobBob]

i agree the cold should have been balanced by being taken off after the prv.

 

[The Real JLC]

Thanks guys. So, could I get a PRV put into the pipe that supplies cold to the shower? Would that reduce the shower output to a trickle?

 

[vipey]

u wouldnt need a prv because u are taking it after the prv that goes into the unvented tank itll be the same presure

 

[Paulus]

As vipey says, this would be the way of ensuring equal hot and cold water pressure to the shower.