Thermostatic mixer shower issues.

[scudo12]

When I turn it on ...nothing no flow. If I leave turned on after maybe 5 minutes it starts to flow slowly then goes to full power but the temperature sometimes fluctuates. Once turned off I can turn it on say an hour later and it flows ok, however if left off overnight I have the same `no flow` again in the morning.

Any ideas what is likely to be wrong (image is similar to mine)

 

[terryplumb]

Is it fed from a vented hot water cylinder and a pump ?

 

[scudo12]

It is fed from a combi gas boiler (central heating) so not a separate cylinder.

 

[terryplumb]

Fed from a combi the hot water would be under mains pressure,as would the cold,so the valve itself is faulty.
Those horizontal bar mixers are relatively inexpensive and easy to replace. I would just fit a new one.

 

[HERTS P&D]

Cheap as chips!

https://www.screwfix.com/p/mulga-exposed-thermostatic-mixer-shower-valve-fixed-chrome/117FV?gclsrc=aw.ds&gad_source=1&gclid=Cj0KCQiA7NO7BhDsARIsADg_hIb7qN-qraMy1pAHj7uzL5UkQY3ppmiHvnHGQzWZb7XKlC2vs24ENBsaArZWEALw_wcB&gclsrc=aw.ds

Andy

 

[scudo12]

OK, to replace do I just need to turn water off at the mains to replace it or is there likely another `turn off` at the combi boiler for the hot water.

 

[Jurassicspark]

Just turn off the water from the stopcock and switch off boiler from mains before replacing.

 

[scudo12]

ok thanks, fortunately we have a separate electric shower upstair so I can take my time.

Thanks all for the replies.