Honeywell CM67/61NG Room Unit Problems

[emptage]

I had a new central heating system installeda couple of years ago and I now have a problem that the heating won't go off. I have a Honeywell CM67/61NG room unit and HC60NG relay box. I turn it off at the room unit but the boiler is still working and all the rads get hot. The little flame symbol on the room unit does not come on and the green light on the relay box does not come on but still the boiler is on and the rads get hot. Any ideas?

 

[corgiman]

sounds like a stuck valve to me

what boiler do you have?

 

[emptage]

It is a Baxi Combi boiler. No hot water tank. It did do this a few months ago then stopped and has just started doing it again, coincidentally as it it has started to get much colder at night

 

[corgiman]

does the light under the tap symbol start alight?

 

[emptage]

Thanks for teh replys.

Sometimes it does but sometimes the rads get hot when it isn't lit. At the moment the Honeywell unit is off but the light on the rad symbol on the boiler is on

Which valve might be stuck?

 

[emptage]

The other thing is that the boiler will be firing and the rads hot but the green light on the relay box next to the boiler is not on which suggests that it is not receiving a signal

Very strange

 

[simond]

To check, remove the wire inside the relay box to either terminal A or B.

Then reassemble.

If the boiler comes on as before, you have no problem with the Honeywell.

If the boiler doesn't come on there is a fault with the Honeywell. A new CMT927 is about £100 and is a direct replacement.

 

[D_Hailsham]

The other thing is that the boiler will be firing and the rads hot but the green light on the relay box next to the boiler is not on which suggests that it is not receiving a signal

Do you get this problem with the transmitter close to the receiver? receiver? If so, when did you last change the batteries in the control unit?

If the receiver does not receive a good signal from the transmitter (low battery or poor signal path), it will go into a failsafe mode. There are two modes: a) boiler turns off; b) the boiler cycles 20% on and 80% off.

It sounds as if your receiver could be in mode B.

The user or installer instructions for the CM67 explain how to change the mode.

 

[emptage]

Thanks for all the replies, I really appreciate this.

The signal path seems ok as when I want to have the heating on then it all seems to work I have changed the batteries to see if this helped but no change.

Thanks anyway