Boiler will only heat water when heating is on.

[Vassagojay]

Hi,

For the first time last night, I had no hot water when I went to shower. We had been out all evening, so I knew we hadn't used all the water.
I pressed the water advance button on my honeywell thermostat, but the boiler didn't fire up. I then hit the heating advance button and the boiler fired up straight away, resulting in hot water.

I tried again this morning, but the boiler would not fire up on the water advance button!!

Any ideas?

The boiler is a Potterton Suprima 40 and is 10 years old.

Thanks, Jason

 

[footprints]

Sounds like a problem with your control valves either a three port or two zone valves, a valve is stuck. Nothing to do with the boiler or programmer.

two of these or one of these