One zone not working, power problem

Old 11-30-07, 07:30 PM
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One zone not working, power problem

I have a four zone system with Taco zone valves at each zone and one circulator pump. I believe I have narrowed down the problem to some sort of wiring problem.

The motor is not receiving 24 volts nor do the wires at the thermostat have 24 volts. On the burner side I've checked all wire connections and everything is tight. All other zones have normal power at both the thermostat and the power head so my transformer appears to be fine.

I swapped out the powerhead and the thermostat unit with ones currently working and both worked fine in other zones. It's just this particular zone.

I would love to tell you that this was a sudden event that just started so I could narrow it down to a change but the fact is that it started being problematic last spring. At the time I figured it could wait until it got cold again... and here we are.

Does anyone have any suggestions as to how I would go about tracing this down? Is there an in-line fuse zone-specific fuse somewhere I could change? Does this connect to my house fuse box and I should look there?

Thanks in advance.
Old 11-30-07, 09:39 PM
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Definitely sounds like a wiring problem...

You need to look more closely at the wiring. You will find a couple of 'common' connections, one wire from each zone valve are probably connected to one side of the transformer with a wire nut. Remove the wire nut and check to see that the wire to the bad zone valve hasn't broken. It may be broken inside the insulation, so look closely. Same goes for the wiring to the thermostats.

Trace the wires from the bad zone valve back with the voltmeter and see where you lose the 24 V ...

What transformer is being used ? The Taco transformer is a 40 VA unit and should only power three valves. You can use one transformer if it's big enough... but most are not.

Are there two transformers then ? maybe one is bad ...

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