Worcester boiler blue light on

[allondon]

Good morning everyone,

I woke up to find the radiators unusually hot. Went to check the Worcester 30Si and the blue light was on even though no demand (fire symbol) was showing. The room temperature was well above the room thermostat (Honeywell, wired) setting. Hot water is fine.
Tried switching the boiler off and on but the blue light keeps coming. No error code, both temperature displays look normal.
Turned heating thermostat on the boiler to a minimum and the radiators slowly cooled down.
The blue light is steady on while previously it was only going on when the demand was on.

Thanks in advance for any ideas.

 

[Chuck]

Thanks in advance for any ideas.

Top of my list would be the zone valve stuck in the open position sending a demand signal to the boiler and allowing circulation.

 

[allondon]

Thanks, @Chuck. I decided to replace the thermostat batteries. The blue light went off and everything seems to work properly again. However, as there was no low battery indicator, I'm unsure if room thermostat was a culprit.

 

[spanner]

Programmer Issue - Or Valve Issue/s