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Taco zone valves and honeywell thermostat not compatable?

Taco zone valves and honeywell thermostat not compatable?I just got a new Burnham Alpine boiler, with a Taco four zone controller and Taco zone valves. The installer left the old thermostats(honeywell, round, old, mercury) and now I think they are not appropriate for this system; the amperage(.05) is way to low for the lowest anticipator setting and the rooms are getting way too warm.

I like the Honeywell round digital. I don't need a programmable. But the manual says it can't be used with taco zone valves.

Is this always true? Can I get around this? Why?

P.S. This site and the  forum members are, by far, the best source of heating knowledge on the web. I've really feal like i've found a treasure.  <a href="http://www.heatinghelp.com/forum-reply/1183015/Taco-zone-valves-and-honeywell-thermostat-not-compatable">Reply</a>


  • GBriggs
    GBriggs Member Posts: 15
    T8775 and Taco valves

    HI ,

    The T8775 Digital Round has a new resistor that makes Taco valves and the thermostat work just fine. You can tell the old from the new because the old model was one resistor and the new one has two wired in parallel. These are installed on the valve. These have been in the thermostat box for some time and maybe the Taco info you have does not note the change. Another option you have is to use a Honeywell TH5110D1006 or a model TH5110D1022 which is a simple battery powered thermostat. Make sure that you set the cycle rate to "hot water" system by reading the "installer set up instructions" with either thermostat you choose.

    Thanks Gary
  • Jfonto
    Jfonto Member Posts: 43
    Yes, Taco mentioned resistors

    But I realized the valves aren't in the same circuit as the  thermostat. the are controled through a relay. So I guess it doesn't matter because the valve won't draw too much amperage through the thermostat. Am I right or no?
  • GBriggs
    GBriggs Member Posts: 15

    The testing that was done showed that the amperage of the valve does go through the thermostat and that is why the resistor was redesigned.  I would install the new style resistors on the valve terminals as shown in the T8775 instructions and you should have no more issues.  Thanks Gary
  • Joe Mattiello
    Joe Mattiello Member Posts: 707
    zone sentry valves

    All thermostats are compatible with the taco zonevalves, heat motor type, and ball valve type.  if the thermostat is a power robbing a resistor is required to keep a trickle of voltage to the valve actuator so the thermostat does not loose it's memory.  Usually, the thermostat mfg will include the correct ohm resistor with the thermostat to be placed between terminals 1, and 2 on the zonevalve.  Hopefully this clears the air. 
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
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