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Taco ZVC406 Revisit

Chas_2 Member Posts: 104
I will take that approach. I replaced the aquastat last night so now if it is doing it, I wont hear it at least.


  • ChasMan
    ChasMan Member Posts: 462
    End Switch Makes on call for heat

    I have an issue with my Taco ZVC406 where the end switch relay makes once in a while on a call for heat. Could this be a zone valve head? I have 4 Taco EBV valves hooked into it (nothing else) and about every five or six calls for heat from any zone the end switch will close and you can here the relay in the Aquastat snap on and off. It just closes for an instant, not long enough for the burner to even start. The valves then charge and operate normally. I tried testing one of the valves and ran the head through about 100 cycles and couldnt get any reading on the end switch. Could this be some line induced feedback? I didnt think these old goats would be that sensitive to EMF or the like. Any ideas?
  • TomMcc
    TomMcc Member Posts: 3

    I forgot to mention that a Beckett Heat Manager device was installed on the boiler earlier this year. I'm not sure if that has anything to do with the blower problem or not.
  • Joe Mattiello
    Joe Mattiello Member Posts: 707

    For diagnostic testing take the zonevalve endswitch off the 3, and 4 terminals and place a shunt on the 3, and 4. This will eliminate the possibility of a faulty endswitch. Let me know how you make out.

    Joe Mattiello
    401-942-8000 X 484
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
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