Concealed shower 2 dodgy cartridges?

[Matt887]

I have a friend whos had a bathroom fitted by someone. The shower is concealed and never got hot from the start. The plumber returned and swapped the cartridge and the shower worked fine for 3 days. Then it stopped getting hot again. Is it likely 2 dodgy cartridges is the fault? The shower is from victorian plumbing. I wonderd of if could be a pressure issue. Thanks.

 

[terryplumb]

Quite possibly either. What provides the hot water , is it from a hot water cylinder fed from a loft tank ?

 

[Matt887]

It's a combi boiler I think.

 

[terryplumb]

Combi runs on mains water pressure ,so that shouldn't be an issue. But you may be wrong on type of boiler ??

 

[Matt887]

If hot water from a cylinder you mean could be unequal pressures?

 

[Matt887]

I was possibly thinking the mains pressure could be too high effecting the cartidge.

 

[terryplumb]

Yes ,that's possible . Thermostatic mixers need balanced pressures.
Gravity fed showers would need cold from the tank in loft. And hot from the cylinder.
If it is a combi boiler both would be under mains pressure.

 

[Matt887]

I've had it before on a combi system we're the shower wodnt get hot unless had the stop take turned right down. Or fit a flow restricter or pressure reducing valve.