Shower temp fluctuating in cold weather

[Aross]

Hi, we have a combi boiler and our shower runs off it. Last winter I noticed the temp in the shower would fluctuate. I would keep turning it up for hotter water and the temp would rise but then drop again. Once it had dropped, if I turned the temp down it would actually go hotter! When the weather got warmer it stopped doing it, however it’s now started doing it again. No issues with the radiators or hot water taps. Any idea what the problem could be? Cadent changed the gas pipes last year, would that have any effect? Many thanks

 

[gas112]

Hi, we have a combi boiler and our shower runs off it. Last winter I noticed the temp in the shower would fluctuate. I would keep turning it up for hotter water and the temp would rise but then drop again. Once it had dropped, if I turned the temp down it would actually go hotter! When the weather got warmer it stopped doing it, however it’s now started doing it again. No issues with the radiators or hot water taps. Any idea what the problem could be? Cadent changed the gas pipes last year, would that have any effect? Many thanks

what make of combi ?

 

[Aross]

Hi, it’s Viessman

 

[monkeysballs]

what temp do you have the hot water set to and is it a thermostatic shower

and what model viessmann

 

[Aross]

Hi, yes it’s a thermostatic shower.

 

[monkeysballs]

I'd try turning down the temp on the boiler it doesn't need to be that high unless your trying to boil veg in your bath but it sounds like the plate heat exchanger is blocked a bit when was it last properly serviced?

 

[Aross]

Oh gosh it’s been a while, I’ll get a service booked in and I’ll turn the temp down too thank you!

 

[monkeysballs]

Often on a service they dont clean it out so mention what's been happening and they likely will

 

[Aross]

Ok I will, thank you so much.