Honeywell RTH7400D controlling Zone control Valve

Old 11-12-05, 06:05 PM
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Honeywell RTH7400D controlling Zone control Valve

Can anyone tell me which terminal to use on a Honeywell RTH7400D Thermostat to give a close signal to a White-Rodgers Three Wire Zone Valve - Type 1311. I can open the valve just fine, just can't get it to shut automatically after I had the thermostat changed from a honeywell T26A.


Old 11-13-05, 04:25 PM
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I think you're out of luck. The key was the 2 in the 26 of the old thermostat. That means series 20 and that means 3 wire control. You can make some sort of relay setup to do it but it will be a wiring pain in the neck. Not many thermostats today control 3 wire zone valves. Honeywelll has a selector on their web site that helps match a thermostat to your system. You could start there.

Old 11-13-05, 07:21 PM
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Thanks Ken. I was afraid of that. The users manual for the thermostat says that it can accomodate 3 wire hot water heat systems. But then you can't control an AC unit. Somewhat misleading. I may have the zone control valve replaced with a 2 wire type, which is the expensive solution.


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