Zone Valve and thermostat Issues

[randy hvac]

I have a boiler i'm working and there are three bad Thermostats. I ohmed out each thermostat to verify. The Zone Valves are Taco Golds. I have 24 volts from the transformer, and i also have 24 volts from the Aquastat. I installed one new thermostat on one of the zones to get the home owner heat for the night, and the burner kicked as well as the circulator. My only concern is, do i have an underline problem, my voltages check out, but i find it hard to beleave that three thermostats can go bad at the same time. The Thermostats that went bad where lux T10-1141SA
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[beenthere]

Sounds like someone miswired something. Find out if anyone else replaced any other parts recently.

[ckartson]

Had simalar issue years ago. Zone valves would open but end switches were faiied on several zones. Another zone call would eventualy start the system. Finally all end switches failed. They asked how could they all go bad at once. They didn't, but they didn't notice that boiler wasn't fireing on calls from several zones. No service contract for someone to test system regularly.

[SolarMike]

I know they are supposed to be almost bulletproof but you can't easily see if the gold series is working properly or have a bad wax motor. I would rather use erie or belimo. That said, is does sound like there is was too much current draw through them and the anticipator may have burnt out (don't know why without seeing it).

[Tempted]

Had simalar issue years ago. Zone valves would open but end switches were faiied on several zones. .

I am replacing 4 tacos same model on 2 homes installed 2 years ago with in months of each other. They open and and fail to close, stuck mostly open. Warranty them with upgrades. Taco knew of the issue back when.

[johnnyx]

i was wondering what the heat anticipators were set on the t-stats?

[SolarMike]

Can't remember but the current draw should be marked on the valve

[GorillaTight]

I think Taco's should be .9 amps, never had much luck with the Lux stats. Might be a silly question, but you're positive the transformers are isolated?

[johnnyx]

gorilla tight is right.9amps and the t-stats heat anticipators should have matched that.if they didn't then that may have been the problem.