Thermostat Problem

[Chewy56]

Could you please detail what Honeywell made you do exactly?
For example, was it an RF communication test, as detailed here: Honeywell DT92E Wireless Room Thermostat Installation Manual - thermostat.guide - https://thermostat.guide/honeywell/honeywell-dt92e-wireless-room-thermostat-installation-manual/#installing-the-dt92-room-thermostat
OR was it proving normal operation of the thermostat, by turning the temperature up and down and watching for the green light on the relay box? If so, did you see the flame symbol come on the thermostat?

It was 'proving normal operation of the thermostat' but as far as I recall I did not see the flame symbol come on. In fact I have not seen that since this started.

 

[Alk]

It was 'proving normal operation of the thermostat' but as far as I recall I did not see the flame symbol come on. In fact I have not seen that since this started.

....and you presumably did that with the Potterton Programmer CH switch set to ON?
Which would mean that the programmer ignores any scheduling and runs the CH 24/7 according to the thermostat.
I understand that the way you use your CH is that in the morning you get up, and switch the slider on the programmer from the OFF to the ON and then when you are satisfied with the temperature, you then slide it on the programmer back to OFF.
Until you feel chilly again, you will then slide the programmer back to the ON again.
Is that correct? Please correct me if I am wrong.

Assuming still that this is the way that you use the programmer, then the programmer won't be faulty, so long as the CH red light goes on when switched to ON, which I am sure it is doing so as shown in your earlier photo.

Did the boiler also fire up and go off when the green light when on and off during the testing?

Have you had your boiler serviced this year?

 

[Chewy56]

....and you presumably did that with the Potterton Programmer CH switch set to ON?
Which would mean that the programmer ignores any scheduling and runs the CH 24/7 according to the thermostat.
I understand that the way you use your CH is that in the morning you get up, and switch the slider on the programmer from the OFF to the ON and then when you are satisfied with the temperature, you then slide it on the programmer back to OFF.
Until you feel chilly again, you will then slide the programmer back to the ON again.
Is that correct? Please correct me if I am wrong.

Assuming still that this is the way that you use the programmer, then the programmer won't be faulty, so long as the CH red light goes on when switched to ON, which I am sure it is doing so as shown in your earlier photo.

Did the boiler also fire up and go off when the green light when on and off during the testing?
I understand that the way you use your CH is that in the morning you get up, and switch the slider on the programmer from the OFF to the ON and then when you are satisfied with the temperature, you then slide it on the programmer back to OFF.
Until you feel chilly again, you will then slide the programmer back to the ON again.
Is that correct?

Have you had your boiler serviced this year?

'you presumably did that with the Potterton Programmer CH switch set to ON?'......Yes

'I understand that the way you use your CH is that in the morning you get up, and switch the slider on the programmer from the OFF to the ON and then when you are satisfied with the temperature, you then slide it on the programmer back to OFF.
Until you feel chilly again, you will then slide the programmer back to the ON again.
Is that correct?'. Yes

' Did the boiler also fire up and go off when the green light when on and off during the testing' I am not sure about that because I was in the loft.

'Have you had your boiler serviced this year' Yes, it's part of the guarantee to have it serviced every year although we have never needed it! Everything else to do with CH but not the boiler!!!

 

[Alk]

To be clear, when the Potterton programmer is in the OFF position, the thermostat won't work. Only when the programmer slider is in the ON position, will the thermostat work. I'm sure that you have already realised this.
It is my opinion from what you have described that if you have the programmer set to OFF, but the relay box green light is ON, then the relay box has theoretically received a signal from the thermostat (a flame symbol) because it wants the boiler to be firing as the room temperature is too low. However, because you have the programmer OFF, the boiler is unable to fire and the boiler is OFF. You have overridden the thermostat with the programmer. Therefore, nothing happens and the thermostat is unable to reach the target temperature of the thermostat and it is stuck like this with the green light on, trying in vain. This is my explanation as to why you are seeing the green light on the relay box "permanently" and why it tests out OK with Honeywell on the telephone when testing simply increasing and decreasing the temperature explained earlier (whilst the programmer is ON).

So, it is my belief now that the green light on the relay box is a red herring as the correct operation has been proved. The only thing that has not been proved indefinitely is with the thermostat in the normal room location whether the signal is OK, but again, if there were an issue with that, then the red light would be lit on the relay box. The red light lights up if a signal has not been received in the last hour. You also say that the thermostat is in the room below the loft and used to work OK. So I doubt that this is a problem.

So, your house goes through swings of cold periods losing heat. Your original question actually was....the thermostat works to bring the temperature up to the target room temperature. However, the thermostat does not seem to be triggering again when the thermostat drops by a few degrees.

So lets focus on troubleshooting that fault and ignore the relay box green light: Where is the boiler located? You need to be looking out for what happens when the target room temperature is reached and then when the temperature drops by a few degrees (still keeping the programmer ON during this period), does the flame symbol on the thermostat come on again? does the boiler fire up? at what temperature does the boiler eventually fire up? and what is the target temperature set to?

 

[Chewy56]

To be clear, when the Potterton programmer is in the OFF position, the thermostat won't work. Only when the programmer slider is in the ON position, will the thermostat work. I'm sure that you have already realised this.
It is my opinion from what you have described that if you have the programmer set to OFF, but the relay box green light is ON, then the relay box has theoretically received a signal from the thermostat (a flame symbol) because it wants the boiler to be firing as the room temperature is too low. However, because you have the programmer OFF, the boiler is unable to fire and the boiler is OFF. You have overridden the thermostat with the programmer. Therefore, nothing happens and the thermostat is unable to reach the target temperature of the thermostat and it is stuck like this with the green light on, trying in vain. This is my explanation as to why you are seeing the green light on the relay box "permanently" and why it tests out OK with Honeywell on the telephone when testing simply increasing and decreasing the temperature explained earlier (whilst the programmer is ON).

So, it is my belief now that the green light on the relay box is a red herring as the correct operation has been proved. The only thing that has not been proved indefinitely is with the thermostat in the normal room location whether the signal is OK, but again, if there were an issue with that, then the red light would be lit on the relay box. The red light lights up if a signal has not been received in the last hour. You also say that the thermostat is in the room below the loft and used to work OK. So I doubt that this is a problem.

So, your house goes through swings of cold periods losing heat. Your original question actually was....the thermostat works to bring the temperature up to the target room temperature. However, the thermostat does not seem to be triggering again when the thermostat drops by a few degrees.

So lets focus on troubleshooting that fault and ignore the relay box green light: Where is the boiler located? You need to be looking out for what happens when the target room temperature is reached and then when the temperature drops by a few degrees (still keeping the programmer ON during this period), does the flame symbol on the thermostat come on again? does the boiler fire up? at what temperature does the boiler eventually fire up? and what is the target temperature set to?

 

[Chewy56]

I would like to thank everyone for their help but it appears this can go no further.

I think the only way forward is either to leave it as it is or get a Hive or similar system to replace the programmer ,thermostat and relay.

I will ring the people who service the boiler and see what they can offer.