eco tec plus 831 boiler wont turn heating on - controller is dead

[Evelyn]

I cannot turn my heating on. the CM921 controller is dead despite changing the batteries. can i turn the heating on via the boiler directly?

 

[Deleted member 120897]

If you have a bdr91 receiver then you can override it, you can’t override it at the boiler without altering the wiring, but this can be done at the receiver if you don’t have an override.

 

[Chuck]

Always worth double-checking that the 'new' batteries are good and they are in the correct orientation.

If the CM927 is really dead (as opposed to working but not displaying anything) the red light on the BDR91 will come on to indicate 'communications lost'. (This happens if it hasn't heard from the thermostat for more than 60 minutes.) In this state the BDR91 will switch into 'fail safe' mode which, unless the default settings have been changed, will have the boiler permanently off.

The manual override referred to by @ChrisB1982 is the push button on the BDR91. One press to switch between on and off. Will be overridden by any signal from the CM927.

Search for 'CM927' using the box at the top right of this page. There have been a couple of threads discussing replacement options for CM927 recently.