Zone valve issue

[bzinsky]

So odd problem.

I have a hydronic heater with 3 zone valves and 3 thermostats. The zone for the basement is controlled by one of those old style ones with the mercury switch inside. If I take the cover off I can see a faint spark when the mercury makes contact, just letting me know it has juice.

So when I switch it to on, the zone valve physically turns on allowing water flow, but for some reason it doesn’t trigger the heater to fire up.

If I turn on my main living room thermostat, it kicks on the heater, and then heats up the basement as well.

So basically I know the thermostat is working since it activates the zone valve. I know the zone valve is working because I can see that little bar on the bottom move to open. I know the heater is working because my other thermostats trigger it to turn on.

Any ideas why my basement thermostat won’t actually cause the heater to fire up? It was working years ago but I never took the time to figure it out since it still has heat if I just leave it on.

Thanks!

 

[bzinsky]

Btw this was all installed by the previous home owner who was a fire chief and had an appliance repair business. He would be a garage journal superstar if he was still alive. I don’t doubt for a second everything was hooked up correctly.

 

[rlitman]

Do you have a relay control box?

 

[brewchief]

Probably a bad end switch in the zone valve.

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[bzinsky]

Do you have a relay control box?

Negative

 

[purplezr2]

What triggers the circulator pump

 

[bzinsky]

So there are 4 wires coming out of each zone valve, it looks like 2 go to 24v power, and I’m assuming the other 2 are signal to the boiler. So I think it’s getting power since it actually moves and opens the valve, I assume it’s the signal to the boiler that’s malfunctioning.

How could I test those wires with a multimeter? Are they suppose to just have zero ohms when the valve is activated?

 

[bzinsky]

What triggers the circulator pump

I don’t think there is a separate trigger per say, I think it just fires up when the heater does.

 

[bzinsky]

....

 

[bzinsky]

12 years of living here, and I just noticed the guy built a removable wall to assist with heater or hwh replacement

 

[brewchief]

The end switch on those valves is either the red wires on the style with the wires built in or the two side by side terminals on the other style.
You can disconnect the red wires and check continuity or do the same for the terminals.

Replacing the powerhead is pretty easy if they are the newer style that doesn't require draining the system down, the newer style has the powerhead separate from the plate and ball that are actually the valve, the old style the plate and ball is part of the powerhead. If you look up honeywell zone valve and look at the installation instructions it's pretty easy to see what needs to be done.

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[The Cobbler]

as said, end switch is bad, or bad connection on that circuit