Honeywell HCW80 thermostat problem

[Andy_cheshire]

I am having problems with the central heating stopping. It seems the communication between the HCW80 stat and the HC60NG is dropping out - the boiler stops but the room temperature has not reached the stat setting point and the green light on the HC60NG has not come on. It should be calling for heat. If I turn the stat down to its lowest setting then up to a high setting and back to its normal setting all is OK again - the green light comes on, the boiler strikes up again and all is well for an hour or so. Then it all happens again. I have changed the batteries in the HCW80 and reset the binding but to no avail. Do I need a new stat? Any advice welcome.

 

[CBW]

Before the boiler turns off, what temperature is the thermostat reaching?

 

[Andy_cheshire]

Hi Chris. The stat is normally set to 20 deg but the boiler usually switches off before the room temp has reached that. The relay is not receiving anything from the stat asking for heat (no green light) although it should be. Not sure if that answers your question!

 

[CBW]

Are you able to test anything? Multimeter wise?

 

[Andy_cheshire]

Yes, I have a multimeter.

 

[CBW]

Check receiver is getting the 240vac. Place a demand on the heating and check live and switched outputs.

 

[Andy_cheshire]

I gave in and called an emergency heating engineer yesterday. He responded very quickly and replaced the thermostat. All seemed well until this morning when it cut out again so the problem must be the receiver. Hopefully he will return today with a replacement.
Thanks for your interest.

 

[ericmark]

The Y6630D thermostat uses an anti-hysteresis software and the same receiver as you have, so yours may be the same, as it approaches the set temperature it starts to cycle off/on so it will not over shoot.

It would have been a great thermostat with this oil boiler, however not very good with a gas modulating boiler as the switching off and on of the boiler messes up the way the boiler modulates so it runs less efficient than if a simple thermostat was used.

However it may not be a fault as such. Have you read the instructions?