Shower hot and then goes cold

[Mr M]

I have a brand new Bristan Artisan concealed shower valve running off my Worcester 240 combi boiler. When the shower is operated, the water initially warms up to the required temperature, but after about one minutes showering, the water temperature drops to cold and stays cold for about 10 to 15 seconds and then the water warms back up again. The water remains at the correct temperature for about another couple of minutes and then the same thing occurs again.

Can anyone offer any suggestions on what the problem could be. Thanks in advance.

Mr M

 

[Dan Robinson]

Scaled up heat exchanger/Calorifier.

 

[Mr M]

Scaled up heat exchanger/Calorifier.

Thanks for the response Dan.

Would this not also affect the other hot water supply taps to the bath, wash hand basin, kitchen sink etc?

BTW, the boiler was power flushed about 18 months ago.

 

[Dan Robinson]

Yes it would, but you notice this problem more in showers.

Powerflushing does not remove scale - that forms in a different water circuit. I can not remember if your boiler has a plate heat exchanger or a calorifier, but descaling either is possible, but not always totally successful. Changing them might be a better option.

One other thing to check is that the shower was installed the right way round (hot and cold suplies to the right ports). It is amazing how common this is done incorrectly. Showers can work perfectly well for weeks and months before they simply give up.

 

[Mr M]

Powerflushing does not remove scale - that forms in a different water circuit. I can not remember if your boiler has a plate heat exchanger or a calorifier, but descaling either is possible, but not always totally successful.

What is the process of descaling? Just so I sound as though I know what I am talking about

One other thing to check is that the shower was installed the right way round (hot and cold suplies to the right ports). It is amazing how common this is done incorrectly. Showers can work perfectly well for weeks and months before they simply give up.

Yes, the hot and cold supply pipes are fitted to the correct ports on the valve

So the problem is definately the boiler and not the shower valve?

 

[gas4you]

With a Worcester I would not attempt to diy. They can be a pig to work on unless you know them inside out. I never touch them apart from a basic service. I always recommend my customers call worcester in on their fixed price £185 call out