I have a Saunier Duval combi boiler, Thelia 23. Hot water works fine upstairs and down when the heating isn't switched on. When it is switched on we are not getting hot water upstairs, although downstairs is fine. We did used to get hot water upstairs with the heating on, but it has got progressively worse each winter. Last year the hot water took forever to heat upstairs and then kept cutting out and coming back on. This year it is not heating up at all, so we are switching off the heating each time we want showers/baths upstairs to get our hot water. Any ideas gratefully received!

Julie Beresford, November 2007

This a truly interesting question. It dos`nt make sense. normal operation , when the boiler fires up for h/w by opening a tap the heating circulation stops.(if on). Hot water is produced but the boiler dosn`t know where the water is going to ie which tap. On a properly working boiler the heating dosn`t affect the hot water. Try and be more precise.

bendan, November 2007