BRISTAN SHOWER runs cold

[whoknows]

Hi

I've seen a previous thread that is closed now regarding this subject but the end result I could not see.
Our Shower runs hot for 30 seconds then cold. I have changed the thermostat and it still runs cold after 30 seconds.
If we run the hot tap it is better but at best, luke warm. We have a combi boiler and I've had a plumber try to figure it out but couldn't fix it. We have another Bristan shower in the bathroom and it works OK.
This one has never been OK.
Can anyone solve this?
Thanks

 

[Gasmk1]

Have you felt the hot pipe when it leaves the boiler, if it is hot then the problem could be a mixer tap passing , if it is not then the flow to the shower is not enough to sustain the hot water call. What boiler is it.

 

[whoknows]

Thabk you for replying. The pipe by the boiler is hot when the shower is on. It is in the loft and is a Worcester

 

[Gasmk1]

Thabk you for replying. The pipe by the boiler is hot when the shower is on. It is in the loft and is a Worcester

How old and what model are you checking the hot water pipe. If it’s hot all The time while shower running. Then problem is not boiler, but the shower most probably. If other shower is ok. Then It shouldn’t be a mixer tap passing.

 

[whoknows]

It's about 8 years old.
The new thermostat is brand new.
The pipe stays hot all of the time by the boiler. It's so frustrating!

 

[whoknows]

Sorry, the model is Sonique

 

[Gasmk1]

If the hot pipe going into the mixer stays hot then it’s a problem with the thermostat. Perhaps he installed it wrong. If not then could be faulty new one.

 

[whoknows]

Thank you, you are a gent. I will speak to Bristan, much appreciated

 

[Chuck]

If it rapidly flips from too hot to too cold when you adjust the temperature then it's possible that the hot and cold feeds are swapped. Make a note of which side is which before calling Bristan.

 

[whoknows]

Hi Chuck

The pipe to the left is the one that gets hot. Should it be the other side?

 

[Chuck]

The pipe to the left is the one that gets hot. Should it be the other side?

Left looking at the mixer is the usual side for a standard shower. Some models offer 'standard' and 'reversed' installation options so it's worth checking.