Thermostat installation


Old 10-09-09, 06:50 PM
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Thermostat installation

I have a Radiant Heating Boiler system with 6 zones connected with a Taco ZVC406EXP zone controller. I recently bought a Omnistat 2 Thermostat from HAI so that I can control the thermostat with a home automation controller. I can not seem to get the thermostat to power up. However, there are only two wires coming out of the ZVC406 to connect to the thermostat. When I connect the RH and W1 wires it turns the thermostat on but it blinks on and off (it has a backlit display) maybe suggesting that it isn't getting enough power?? There is a jumper between the RH and RC leads too, and I tried to remove this and it did not work either.

Anybody have any suggestions or comments on how to connect the two? Are the two not compatible, do I need a common wire, and if so how do I get a common wire from the ZVC406 as there are only 2 connections per zone for the thermostat? Thanks in advance for any help you can give.
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Old 10-10-09, 06:28 AM
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Looking through the install for that thermostat, there are instructions for having to use a common wire. You should be able to pick up that common wire from the terminal strip in the ZVC panel.

Here's a link for 'helpers' to follow to look at the install PDFs for the OMNI thermostats:

HAI Omnistat2 Thermnostats

Also notice (scroll down on page) that there is a 'power module' available for the thermostat.

I'm going to move this over to the 'thermostatic controls' topic, because I think you can get better help there.
Old 10-10-09, 08:58 AM
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I don't see where to pull the common from the ZVC406? Does anyone know if this is possible or is there a different zone controller that does have a common?
Old 12-06-09, 09:08 AM
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Common wire

I don't have a zone controller, but other than that have a similar system. So without knowledge of the zone controller panel, I can tell you that I have a common wire to my thermostats. The common wire comes from the non-power side of the transformer (the side with the 'white' wire).

I didn't install this system and I'm not an electrician.

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