Taco ZVC403 Zone Valve Control not powering up


Old 06-29-20, 01:20 PM
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Taco ZVC403 Zone Valve Control not powering up

I am installing a new Taco ZVC403 Zone Valve Control unity and initially it powered up fine and worked with my old thermostats. Then I started adding new Honeywell Thermostats, two T6's and one VisionPro 8000. The T6's worked fine, but the 8000 wasn't engaging the unit.

The Taco is connected to an oil burner/pump system for radiant flooring.

After transferring the black wire from the C terminal to the W terminal on the 8000, (it is only a two wire hookup because there is no fan) because the C terminal didn't seem to work, I checked the 8000 LED lights and nothing was on, not even the green power on light. I checked the inline 5amp fuse and it was fine. But there appears not to be an power to the board itself. There is 120V to the transformer....

Any ideas? Did I blow the 24V transformer with my hooking up the black wire to the W slot instead of the C slot on the Honeywell 8000? It is a mystery to me.

BTW, the Honeywell T6s are hooked up to the W slot with the black wire, and the red wire to the red slot.

Any help would be appreciated.
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Old 06-29-20, 01:31 PM
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Welcome to the forums.

I moved your thread to the boiler forum.
The visionpro stat runs better on three wires to operate.
An R, W and C.

Actually.... the T6's require a C wire too. Three wires.

Post a picture of the Taco control.... How-to-insert-pictures.

Last edited by PJmax; 06-30-20 at 09:18 AM.
Old 06-30-20, 08:05 AM
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Hi, if you have only 2 wires at the 8000 use R&W , have you installed batteries? T 6 will operate with 2 wires as long as batteries are installed C wire is optional.
as Pete stated post some pics.
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