Gloworm 40FF Boiler Not Switching Off

[leonjudge]

I have a gloworm 40ff boiler, danfoss fp715 HW/CH timer, and a Honeywell cm907 programmable thermostat.

This morning the temperature was set at 21, on the Honeywell unit, however the temperature managed to get to 25 degrees - the boiler was running constantly.

The normal setting on the danfoss timer is HW to Auto (a programme turns on in the am and pm for an hour) and the CH is always on - as the Honeywell cm907 controls via its own programme.

I turned the CH to off (on the danfoss) and the boiler continued, I also turned the HW to off and the boiler continued too. The only way to stop it is to either turn the knob on the boiler to 0 or very low, or turn the power off to the danfoss. (I assume the switch to the right of the danfoss is its power?). It's a fused connection unit.

Is it possible that the danfoss is still feeding the boiler with power even though the programme is set to off? Or more likely to be a boiler issue?

Thanks

Leon

 

[45yearsagasman]

Could be, but it's more likely to be a fault with something like these View media item 30391 View media item 38425Your programmer controls the valves first via a stat which then tells the boiler (and pump) to start.

 

[leonjudge]

Thanks - I have taken the danfoss timer off the connection block which is screwed to the wall. With the FCU switched on the boiler still starts so I assume that rules the danfoss timer out?

 

[leonjudge]

There are two of those in the airing cupboard (the boiler is in the kitchen) and both are set as auto. One of them moves to manual (with a bit of give) and then sets back to auto and the other is loose to about 3/4 of the way to manual and then does the same. Does that help?


Update

After moving these and refitting the danfoss unit - all is working ok

 

[leonjudge]

And finally - the pump was replaced about 3 months ago after it failed - just in case it could be linked?

 

[ianmcd]

The one that is loose is what is causing the problem its a good chance that it is just the synchron motor has seized they are about £15 and easy to replace, turn all the power off nad remove the silver cover, its only held on by one small screw and you will see the synchron motor, it will be attached to the valve body by sometimes one sometimes two very small screws, take it out and if the gearing mechanism springs back its the motor you need to change if it doesnt spring back then the vave has seized try freeing it off manually but dont use WD40

 

[leonjudge]

Thank you - will give that a go.

Are the motors specific types for different units, these are danfoss?

 

[ianmcd]

same motor , I buy ACL drayton ones just for ease but they are all the same