problem showers from combi

[drainrod]

Worcester 35 CDI two different shower valves, I of which is brand new, both showers run hot for say 5mins then start to run cold for 3-4mins then hot then cold again, no taps being opened elsewhere in house
any help please?

 

[ShaunCorbs]

Both showers run at the same time or individual?

 

[drainrod]

Worcester 35 CDI two different shower valves, I of which is brand new, both showers run hot for say 5mins then start to run cold for 3-4mins then hot then cold again, no taps being opened elsewhere in house
any help please?

 

[drainrod]

both showers NOT running at same time

 

[ShaunCorbs]

Does the boiler stay alight or does it go out as well

Also is the kitchen hot tap doing the same ?

 

[drainrod]

both showers NOT running at same time

Does the boiler stay alight or does it go out as well

Also is the kitchen hot tap doing the same ?

kitchen tap ok. just when shower on ,boiler kicks in and out

 

[ShaunCorbs]

Hot and cold piped up correctly to the showers ?

 

[rpm]

Balancing issue between hot and cold?

 

[drainrod]

Hot and cold piped up correctly to the showers ?

def. plumbed right

 

[drainrod]

Balancing issue between hot and cold?

thinking more of boiler issue? diverter valve??

 

[ShaunCorbs]

def. plumbed right

Are they bar showers ??

 

[drainrod]

Are they bar showers ??

1-grohe thermostatic concealed 1- crosswater kai 3 thermostatic valve

 

[ShaunCorbs]

Do you know if the filters were cleaned ?

Doesn't sound like a boiler issue as the hot tap is fine

 

[Allgoode]

Sounds like a bit of cross-flow from the cold supply to the hot water from combi.
Do you have any check valves on pipes to shower valves or non return valve on hot water out from combi?
cheers,
Andy

 

[drainrod]

Sounds like a bit of cross-flow from the cold supply to the hot water from combi.
Do you have any check valves on pipes to shower valves or non return valve on hot water out from combi?
cheers,
Andy

no

 

[drainrod]

Do you know if the filters were cleaned ?

Doesn't sound like a boiler issue as the hot tap is fine

filters very clean