I have just installed a Honeywell CM67 NG Thermostat and need some advice on how to tune it. The Installation and User instructions are no help at all.
It seems to be doing its job - the house is warm when we get up and the temperature is staying fairly constant. My main concern is the way the boiler is continually starting and stopping, sometimes for only a few seconds. In fact just now when it started there was a loud bang - don't know where from exactly - and the whole house shook. I have turned the thermostat over to manual for the moment until the cause is found.
My guess is that the problem is due to the boiler warming up and cooling down too quickly.
The thermostat has three adjustments: Minimum on Time (set to 1 minute); Cycle Rate (set to 6) and Prop bandwidth (set to 1.5 deg C).
In what order should I change these and what effect will they have?
My boiler has an overrun thermostat which controls the pump. I have noticed that the pump keeps running for a long time after the boiler stops firing. I put a thermometer on the inlet to the pump and found that it was still running when the temperature had fallen to 30 deg C. Is this to be expected or is the pump staying on too long - faulty t'stat?
It seems to be doing its job - the house is warm when we get up and the temperature is staying fairly constant. My main concern is the way the boiler is continually starting and stopping, sometimes for only a few seconds. In fact just now when it started there was a loud bang - don't know where from exactly - and the whole house shook. I have turned the thermostat over to manual for the moment until the cause is found.
My guess is that the problem is due to the boiler warming up and cooling down too quickly.
The thermostat has three adjustments: Minimum on Time (set to 1 minute); Cycle Rate (set to 6) and Prop bandwidth (set to 1.5 deg C).
In what order should I change these and what effect will they have?
My boiler has an overrun thermostat which controls the pump. I have noticed that the pump keeps running for a long time after the boiler stops firing. I put a thermometer on the inlet to the pump and found that it was still running when the temperature had fallen to 30 deg C. Is this to be expected or is the pump staying on too long - faulty t'stat?
