Dual circuit gas boiler question

Ger Roe

I had a new baxi condenser gas boiler fitted a few years ago and a new separate hot water (to taps) circuit was installed at the time - tap water stored in existing immersion tank.

All worked well until about two years in when a new annual service man turned some stop cocks in the hot press (at immersion tank) and ever since, we have scalding hot tap water during summer (when rad heating circuit is not operating) and only luke warm tap water in winter (when rad heating is operating).

Basically, if the rads are operating at the same time as the hot tap water circuit, then the immersion tank does not heat up properly. If the tap hot water circuit is operating on it's own, the immersion tank heats fully.

I have put up with this for a few years, but am fed up of it now. The service engineer says he did nothing to affect the system, but I can quote the problem as appearing the day of a specific service and forever since.

I don't know how these systems operate - should the rads and tap water circuits be totally separate systems and if so, what possible valve adjustments could have been done to allow the immersion tank hot water to drain when the rad circuit is on?

Any advice would be appreciated.

Ger Roe

Ger Roe wrote: »

I had a new baxi condenser gas boiler fitted a few years ago and a new separate hot water (to taps) circuit was installed at the time - tap water stored in existing immersion tank.

All worked well until about two years in when a new annual service man turned some stop cocks in the hot press (at immersion tank) and ever since, we have scalding hot tap water during summer (when rad heating circuit is not operating) and only luke warm tap water in winter (when rad heating is operating).

Basically, if the rads are operating at the same time as the hot tap water circuit, then the immersion tank does not heat up properly. If the tap hot water circuit is operating on it's own, the immersion tank heats fully.

I have put up with this for a few years, but am fed up of it now. The service engineer says he did nothing to affect the system, but I can quote the problem as appearing the day of a specific service and forever since.

I don't know how these systems operate - should the rads and tap water circuits be totally separate systems and if so, what possible valve adjustments could have been done to allow the immersion tank hot water to drain when the rad circuit is on?

Any advice would be appreciated.

If you have a timer then have your hot water come on a hr before your heating, on your next service get the RGI to make sure you cylinder stat is set to 60c( or you can have a quick look yourself)

Ger Roe

gary71 wrote: »

If you have a timer then have your hot water come on a hr before your heating, on your next service get the RGI to make sure you cylinder stat is set to 60c( or you can have a quick look yourself)

Thanks for the response. The stat is set correctly.
I had thought of putting the water on separately alright, but that would mean an hour earlier boiler and pump noise in the very early morning, fact is that it all worked perfectly .... until the valves were twiddled during a service and I can't figure out why, or what was done.