Honeywell ST9120C thermostat is On but CLAS HE Ariston boiler won't fire up

C

Cocora

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Hi!

I just moved to a new property and I cannot make the boiler to fire up the heating.
I have a CLAS HE Ariston boiler. It was turned off when I moved. I turned it on, turned on the hot water, and all is good and working great.

But today I wanted to test the heating, and the boiler won't come up.
The thermostat batteries were dead, so I changed them and I programmed the thing for different days/etc. as per manual.

I can also override and I see the little fire icon on in both the hall thermostat and the panel next to the boiler, but the boiler is still not firing up.

upload_2020-8-16_18-26-37.png


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In the manual, is looks like the display should show a C and two numbers, but is only showing 0 and 2 numbers.

upload_2020-8-16_18-32-29.png


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The line should be blue as well, and nope...

For the hot water, if I adjust the temperature from the boiler, or if I open the hot water tap, it will show correctly the "d" followed by numbers in the boiler display, and all works fine.

upload_2020-8-16_18-27-7.png


Also, the boiler is connected to this pump, dunno if there's anything to check there as well?

upload_2020-8-16_18-22-9.png


Does anyone know what could be happening? :eek:

Cheers!
 

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What’s the current temp set to in relation to the room temperature?
 
Chris_W said:
What’s the current temp set to in relation to the room temperature?
Click to expand...
room temp 17, thermostat 19. It's showing the flame symbol in the thermostat, so is not an issue there.
Cheers!
 
Bit of a long shot but possible, the pump in your pic is a condensate pump, it has an alarm wire that cuts the power to the boiler if the float gets too high, it is possible that this may have been wired to interrupt the CH demand rather than the live to the boiler, I have seen that before and if the pump is full it wont allow the heating to come on
 
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