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Wiring a thermostat for radiant heat.

skipinsc's picture

I'm building my own home in SC and I have radiant hydronic heat.  I'm out of market so trying to get this done has been a challenge.  I think a simple question, but how do I wire a 2-wire T'stat for the radiant floors.  Unfortunately the T-stats don't have a "red and white" connection.  They have a NC-NO-C.  I don't know which wire goes where. 

I have already blown one transformer on the Taco ZVC unit.  I've traced every wire from the manifold actuators and the T-stats and no wire was crossed or mixed up. 

Here is a link to the manual for the Tstats:

Here is a link to the Taco:

It's obvious what goes where on the Taco....

Thanks for the help

For heating only in a 24VAC (post #215944, reply #1 of 4)

For heating only in a 24VAC circuit it doesn't much matter, but to keep the OCD folks happy wire red to "NO" and white to "C".

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Thanks for the info, I'll (post #215944, reply #3 of 4)

Thanks for the info, I'll keep looking to see what it could be.  Perhaps I need to check all my connections. 

Skip, (post #215944, reply #2 of 4)

There is no way to wire a 2 wire stat wrong that would kill a transformer so you have a different problem. Think of it as a 2 wire light switch. It is either on or off.


Using a on/off t-stat is a (post #215944, reply #4 of 4)

Using a on/off t-stat is a poor way to control a hydronic in-floor system. Some research will show you better ways.