Central Heating Permanently ON.

[Ashy28]

I have a Drayton Tempus 6 programmer, and today I initially found that the CH did not coming on as normal, even though the programmer said it was on. I checked the thermostat (and also bypassed it) and the CH would still not function. I checked the wiring to the programmer back plate and all was fine. After re-connecting the programmer, and with the programmer still saying the CH was on I activated the manual override on the 3-way valve and the system started. However when I switched the heating 'off' on the programmer the CH remained on. I thought that the 3-way valve was stuck, but on investigation it was still receiving power from the programmer and therefore remained ON (the boiler is also on). I Switched off the mains power to the programmer, and as you would expect the CH stopped, the boiler stopped,and the 3-way valve also closed.

I am now finding that even when I switch power back to the programmer, and with the programmer telling me the CH is 'off', it actually comes on and remains on. Moving the thermostat right up and right down (passed the 'click') has no effect...the CH remains on. The only way to shut it off is to switch off the mains power to the programmer.

Based on the above, can I safely say that the programmer is at fault and should be replaced, or can someone shed any more light on this problem. Is there any way to re-set the Drayton Tempus 6? I see a battery inside on the circuit board, but this is fixed - should I switch off mains power for a number of hours to re-set it???..thanks.

 

[Agile]

Most programmers have a hard reset little button.

I would say that the system may be wrongly wired and the motor valve microswitch(s) may have failed.

If only the programmer was faulty then the thermostat would still switch it off.

Tony

 

[ELZ4742]

i would deffo say it was the valve. remove the orange from the harness and test with the clock in the off position, if its perm live chances are its the valve.

also other things to check are, is the prog set for a gravity system?
if you are using a honeywell pcb harness have u cut the correct links?

 

[Ashy28]

Thanks for your advice ELZ4742

i would deffo say it was the valve. remove the orange from the harness and test with the clock in the off position, if its perm live chances are its the valve.

I have removed the orange wire coming and can confirm that this is permanently live - it is live when the CH signal is ON, but remains live even when the CH signal is OFF in the programmer. How confident are you that this is a valve problem?

What is the logic within the valve, and what signal does the orange line give? I assume from your troubleshooting, that this orange line should not give a live signal when the CH should be OFF.

With thanks.

 

[Ashy28]

Thanks Tony,

I could not find any reset button on my programmer. However your comments on the valve microswitches may be correct. I don't think the system is wrongly wired as it has been functioning OK for years. I am sourcing a replacement Valve controller (Honeywell V4073) and hopfully will be able to change this within the next few days...I'll tell you the result in due time.

Cheers
Paul

 

[weareleeds]

1,hot water only 240v on orange wire.
2,htg & hot water 240v on orange & 240v on white/brown valve drives to mid position with the use of a bridge rectifier on valve pcb only allowing approx 115v to motor.
3,htg only 0v on orange 240v on white/brown & 240v on grey which by passes bridge rectifier & allows 240v to motor which powers over to close dhw port & make end switch which sends 240v to orange