Problem with Honeywell ST9420C

[PJ100]

Good morning and Merry Xmas.

I have recently had a new Worcester Bosch Boiler and Honeywell ST9420C controller fitted.

It seems as if when the water is up to temperature, the central heating won't run. ???

Yesterday, we had the water and heating on 'Continuous' during the day. In the evening when we wanted the radiators on again (and I had switched it back to Auto) the water light would not come on, although the tap symbol was on.

The CH light was on, but no water was circulating and the radiators were cold.

The boiler temperature was reading 25deg c.

In the end we got it working, but we don't know how!! This involved running the hot water off and turning controller to OFF for about 10 minutes...this doesn't seem right!

We would be grateful for any advice to help us with this Christmas frustration!!!

Thanks

 

[Terry lambert]

I would get your installer back to check the wiring, or if it worked upto this point, to look for a brokenor loose cable

 

[Whitespirit66]

As above, poss wiring. If you turn the cylinder stat right up, does the ch work? Sounds like the cyl stat is controlling heating...............but I'm clutching at straws.

Time to drag the installer away from his turkey leftovers.

 

[PJ100]

Yes I agree. It seems that when the cylinder is up to temp the green light on the controller won't come on. It seems illogical that the only way to run the CH when the tank thermostat is satisfied is to run off hot water.