Boiler hot water flunctuates

[TAMD8389]

Hello plumbers.

I am having an issue, where the hot water coming out of the shower head would sometimes go cold. I don't know if the problem is with the combi boiler, or the shower mixer, but it does annoy me. It is a standalone combi boiler, with no additional hot water cylinder. The water would normally be hot, but sometimes it turns cold. If I increase the output of the shower mixer it turns hot back again. The shower is upstairs, and the boiler is in the utility room. Please can someone advise how can this problem be resolved. Thank you gentlemen.

 

[gas112]

What make and model of combi?

 

[accelerator]

Is anyone else using water whilst you're having a shower?

 

[TAMD8389]

What make and model of combi?

Valiant ecotec but not exact sure on model.

 

[TAMD8389]

Is anyone else using water whilst you're having a shower?

Nope. Only me using the shower.

 

[accelerator]

Do you have any fluctuations in your supply water pressure, as this could affect the combi boiler. If the supply pressure is dropping, it might affect the combi and make your hot water run cold.

 

[TAMD8389]

Do you have any fluctuations in your supply water pressure, as this could affect the combi boiler. If the supply pressure is dropping, it might affect the combi and make your hot water run cold.

Thanks.

I don’t have any cold water fluctuations, but I believe that if I did, it wouldn’t cause my issue, I.e, water becoming cold.

Instead it would have just stopped outputting water if it was a cold water pressure problem.

 

[Scally-Ho]

Nope. Only me using the shower.

I expect your boiler's flow sensor is either malfunctioning or your HW set temperature is set too low causing the boiler to alternate firing.

 

[gas112]

Is it doing it when running the hot taps as well or just the shower

 

[TAMD8389]

Is it doing it when running the hot taps as well or just the shower

Just the shower as far as I’m aware.

 

[TAMD8389]

I expect your boiler's flow sensor is either malfunctioning or your HW set temperature is set too low causing the boiler to alternate firing.

Thanks but please explain your theory behind this.

 

[Scally-Ho]

If the hot water demand is less that the boiler's lowest modulated output, then it will alternate firing and in turn cause fluctuation is HW output temperature.

 

[kidgreen61]

If you're sure the fault is shower related only, and definitely doesn't happen with hot taps, then I'd be looking at shower valve.

 

[TAMD8389]

If you're sure the fault is shower related only, and definitely doesn't happen with hot taps, then I'd be looking at shower valve.

Thanks but what would be wrong with the shower itself and what part would need changing and say if the other taps were affected too what would be wrong with the boiler?

 

[TAMD8389]

I'm going to bump this thread as no one has seemed to bothered to reply.

Anyone?