Boiler comes on after time clock has been removed from wall

[hoover]

Hi just looking peoples thoughts on this one. I went to check out a 3 channel hortsmann time clock. I found it to be faulty as the display came and went. It’s about 12 years old and apparently when the internal battery fails it time to change the clock as you can’t access the battery.
Anyway, I removed it from the wall with the view of getting a new one within a couple of days but thenguy in the house now tells me the external boiler still runs.
Upstairs heating, downstairs heating and hot water controlled from the time clock. Each circuit has an individual stat and valve. With the clock removed the boiler shouldn’t of been getting a call signal.
I’ve to go back and fit the new time clock but I’m confused as to why the boiler still fires up. Perhaps a faulty valve? But then the valve should of been getting a signal as the time clock was removed. The back plate of the time clock does appear to be wired correctly.

 

[Sintra]

Valve could be on manual override making the auxiliary contact and sending signal to the boiler.

 

[hoover]

Valve could be on manual override making the auxiliary contact and sending signal to the boiler.

Unlikely the valve has been put to manual as no one lives in the house and the owner said he never tampered with anything. Sounds like the valve maybe stuck?

 

[123]

One of the 2 port valves is likely to be faulty, sending a call for the boiler to fire. As the valve won't have opened the only way to identify which one is it is to test for 230v on the core used to call the boiler from the 2 port valve- usually orange but some people do use the grey.

 

[fairlight]

A possibility is a faulty frost stat in the external boiler

 

[Midwest]

I’ve had a port valve fail before now, contacts make and CH on all over the weekend. Was like the Sahara desert, when I arrived back home.

 

[davesparks]

8f the boiler is external it will have some form of frost protection which is probably what is causing to to fire.