Pressure Balancing Valve

[messy69]

When fitting a Thermostatic Mixer Shower fed from a Fully Modulating Combi boiler is it necessary to fit Pressure Balancing Valves?

My reason for asking is as my mains fed cold supply is quite powerful, not sure how many bar, and the hot from the combi a lot less

If so whats the best to buy, what cost and how easy & how/where do they fit?

Not a plumber so please be basic!

 

[ChrisR]

mains fed cold supply is quite powerful, not sure how many bar

You do need to know how many bar! You can buy a guage from a plumbers merchant for a tenner. If it's more than 6 check your combi's input limits. A thermostatic valve might start to have problems too. If either is a problem, a pressure reducing valve on the mains would be appropriate.

 

[messy69]

Right, have checked the mains feed water pressure and it is 4Bar.

Boiler states -

"Flow 35 degrees C temp. Rise 11.6 l/m"
"Domestic hot water specific rate 13.6 l/m"

So do I need any "special" valves to install between the boiler produced hot water and the Thermostatic Shower valve and before the cold enters the Thermostatic Shower valve ??

 

[kevplumb]

have you seen the price of pressure balancing valves

think i would try it without first

 

[oilman]

It's probably the flow rate that's the problem, as the pressure will be the same on hot and cold taps until they are turned on. The boiler probably has a flow regulating valve in it hich is just a calibrated restrictor, so if you put one of these restrictors in the cold feed to the thermostatic valve, it might reduce the problem.

 

[ChrisR]

What problem - nobody said there's a problem!

4 bar isn't special - some people have over 10! THAT is a problem! You can use a normal thermostatic shower mixer, but they can be troublesome under some circumstances - it seems to be the cheaper ones. Mira, & maybe others, make a pressure balaning shower mixer, which is designed FOR combis, and it works very well.