Taco Zone Valve Issue


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Old 01-20-13, 06:23 PM
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Taco Zone Valve Issue

I currently live in a 8 unit condo building with a common boiler and a Taco zone valve in each unit. The Taco zone valve in my unit stopped working recently and I've tried to unsuccessfully troubleshoot it with help of this forum.

I've replaced the thermostat with a CT87K thermostat and the Taco zone valve power head with no success. I am able to move the manual handle on the power head to the ON position and feel the hot water running through the pipes to heat my condo but cannot get the unit to operate automatically. I checked the voltage from the transformer to the 1 and 2 positions on the power head. Both positions constantly show 25VAC, even when the thermostat is turned all the way down. Any help getting this solved would be greatly appreciated. Thank you all in advance.

Matt
 
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Old 01-20-13, 07:07 PM
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constantly show 25VAC, even when the thermostat is turned all the way down
This is odd because by all rights, that valve should then be open all the time and roasting you out.

No wire on terminal 3 I presume? I'm presuming that the common boiler is set up to stay hot all the time and deliver hot water to any unit on demand. So no wire on endswitch?
 
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Old 01-21-13, 03:16 PM
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Correct, there is no wire on the end switch and the boiler is on all the time. I can open the valve manually and instantly have hot water flowing through the pipes.
 
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Old 01-21-13, 03:47 PM
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That's bizzarro...

If 1 and 2 are powered all the time, the valve should be open all the time.

It just doesn't make any sense at all!

Have you measured the voltage at the two thermostat wires? With them disconnected, you should see 24 give or take there as well.

But still, this won't explain why the zone isn't open all the time. It might tell us if the thermostat wires are shorted and explain why there is voltage all the time... but not why the valve isn't opening.

Is the zone valve head hot to the touch?
 
 

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