Skip to main content

Ready to hire?

Post your job in minutes, browse real reviews and choose who to speak to.Post a job

Need some tips or advice?

Ask a question
Central Heating

Central heating activated when hot water tap / shower is on - Combi Boiler

Anonymous user 03/03/2024 - 3.36 PM

Hi all, First off, I'll start by saying that most likely my 11 year old Vaillant boiler is a write off. My central heating has never been working properly but I was always getting hot water in the shower / taps. Long story short - despite powerflush, I still wasn't getting circulation to all radiators - only the one in the bathroom & second room get hot. Had Vaillant around, he tinkered with the boiler for 2 minutes, said main issue is with the heat exchanger & left after declaring the boiler beyond economical repair. He left it on as it still functions for hot water. I took a shower later that evening & noticed for the first time the bathroom & second room radiators get hot when the hot water is running, despite my central heating being off. Even if I use the kitchen sink hot tap, those two rads get hot. Looked at the boiler and saw the flame icon lights up every time I turn on the hot water tap. There's no noticeable temperature change / lack of hot water in the shower or taps, just now the central heating is activated when hot water taps are in use. What could cause this? Is this caused by the powerflush or whatever tinkering Vaillant did? It's not causing a major issue as I will need to replace the whole boiler, but is it unsafe to use with the hot water meant for the taps going to the central heating? I can live without CH, but not without hot water, so as long as nothing is going to blow up between now and the new boiler, is it still safe to use the hot water taps?

Are you a tradesperson and able to answer this question?

2 Answers

TopHeatWork’s Ltd

Rating: 5 out of 5
Hounslow
This could be two things, diverter valve or the domestic hot water heat exchanger, if the hot water is not coming hot as it should then the heat exchanger is blocked and its pushing the hot water to the central heating side
Answered17 January 2021
3

Anonymous user

As an ex Vaillant engineer I’m going with the diverter valve depending on model but 99/100 it’s that valve
Answered14 February 2021
0