Discuss Programmer/Thermostat wiring CH problem? in the USA Plumbers Advice area at PlumbersForums.net

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Hi Guys,

Hoping someone can help me, we have a 2-zone heating system that consists of 3 honeywell 2-port valves on a system/hot water tank gas boiler.

Recently the HW motorised valve broke - so I replaced it (motor/housing only) and problem solved. However when diagnosing this, I also noticed that CH2 ignores the thermostat and is always calling for heat. That is, when the thermostat is on 0 and the CH2 is on at the programmer, it's always firing up the boiler. CH1 is working correctly.

I figured it was probably the valve, so replaced that along with the HW valve while I was at it, however the problem remains exactly the same. So next I figured it must be the thermostat, so I replaced that like-for-like (£20 honeywell) and problem still remains the same! The thermostat is clicking correctly and my current buzzer shows it is certainly 'getting power'.

So now, I believe it must be either the programmer faulty on that single channel, or the wiring is bad, and has been bad since it was first installed? I've only been here 2 years and honestly not sure if this is a new or old problem - so the wiring seems more plausible?

Does anyone have any suggestions for diagnosing? Or should I just get a plumber in at this stage? I could buy a multimeter but can't say I'm confident with using/diagnosing it.

This is the system layout (attached)

This is the wiring box, black wires are the valves and the left hand side white cables are CH2/HW thermostats (attached).


Thanks for any help!
 

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The CH2 valve should only motor over and connect the endswitch with permanent live to boiler live when theres a call from programmer and through stat. This really needs a multimeter. Even if the programmer was faulty and sending a constant feed the stat should still govern the feed to motor.
 

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