Honeywell Digital Thermostat Issues

jassel

Thermostats = Honeywell T8775A “The Digital Round” Non-programmable, Heat-Only



Zone Valves = Taco 571



Zone Valve Panels = ZVC - 403

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The components listed above were installed brand new and brought on line December 30th.  On January 1st, one of the thermostats was reading 80 degrees room temperature even though the temperature wasn’t anywhere near 80.  The flame icon on the thermostat indicating a call for heat was not displayed.  Both the thermostat and zone valve indicator lights on the zone valve panel light up very faintly for a few seconds and then would turn off for a few seconds, and so on.  It did not appear to activate the circulator panel.  The radiator was hot, which leads me to believe the zone valve was open, but only received the hot water when another zone activated the circulator.  I removed the face of the thermostat and replaced it a few seconds later.  Then the readout on the thermostat just steadily blinked on and off.  I noticed the thermostat was warm and I could hear a buzz when I put my ear up to it.  I swapped it out with an old bi-metal Taco thermostat and it worked like normal.  </span>

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The following evening, another thermostat was experiencing the same thing.</span>

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The resistors are snuggly screwed into Terminals 1 and 2 and bent away from the powerhead per the instructions.  The resistor can’t be installed “upside down” can it?  Either wire of the resistor can be attached to either terminal 1 or terminal 2, correct?</span>

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Is it possible for the W wire and R wire from the thermostat to be “crossed” with the zone panel?  If so, the panel doesn’t specify which terminal to attach the W and R.</span>

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One of the thermostats on the panel is mercury, but that shouldn’t be a factor, right?</span>

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We’re pretty perplexed by this.  Any ideas on what is causing this or what to check?</span>

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Thanks - Jason</span>

billtwocase

resistor or not

Those thermostats don't work with Taco. I found out the hard way. The ones I installed, the customer had bought because they had a large display, light, and digital accuracy. They worked a few days then spiked the house temp-wouldn't deactivate the zone valves. Quick call to Honeywell, and was told not compatible.