DIY Doctor UK DIY Forums

Hi all - hope everyone had a nice Xmas!

Help - I have no heat! I have a Honeywell CM907 7 Day Prog Thermostat (installed by qualified Electrician) controlling my Alpha CD32C combi boiler and heating system which was all installed around 3 years ago (by Corgi installer). As of today, the CM907 is calling for heat but my boiler isn't firing. The boiler is fine as it fires when I turn on the hot water and the heating worked yesterday. I've checked the boiler pressure and this is fine too.

Not sure if relevant but over the last few months some of the buttons have stopped working on the CM907 (Time change, copy day, day select, program buttons, OK button etc). I don't know why this has happened?

I can only assume at this stage that the CM907 is at fault as it is calling for heat but for some reason this signal isn't getting through to the boiler?

I've contacted the Honeywell helpdesk (closed until 4th Jan) and the installer has gone away skiing and I therefore have 2 questions to you good chaps:

1. Does anyone have any ideas what this could be?

2. Is it possible to manually fire up the boiler in the meantime, i.e. independently of the thermostat calling for heat?

Thanks in advance.

If you have boiler manual, go to page 32, diagram 9.2 and fit the link to terminals 1&2 this does away with external controls. If the boiler works you know it's the CM907 at fault. You can then use boiler controls to turn CH on/off.

or

As you know the CM907 has faults, like buttons that aren't working, you could buy a new CM907 and see if this solves the problems.


htg

htg engineer wrote:If you have boiler manual, go to page 32, diagram 9.2 and fit the link to terminals 1&2 this does away with external controls. If the boiler works you know it's the CM907 at fault. You can then use boiler controls to turn CH on/off.

or

As you know the CM907 has faults, like buttons that aren't working, you could buy a new CM907 and see if this solves the problems.

htg

Hi mate, thanks for your reply. I did make a link but at the CM907 wiring instead at the suggestion of another helpful guy on another forum. This worked and the boiler fired up which I assume means the CM907 is at fault.

Thanks again.