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Taco ZVC-406 not opening zone valves

I have a ZVC-406 that does not open any of the 5 zone valves (honeywell V80431012) connected to it. It appears the thermostats are calling -- the lights for the zone on the controller flash when I turn the thermostat all the way up and go off when I turn the thermostat down. When I manually move the valve open, the boiler fires up and water circulates.

The system is about 10 years old and has not had any issues - nothing has been replaced in the controller or valves.

I put a multimeter on the wires connecting the valve to the controller and there is some power going, maybe not enough?

Any help would be appreciated.

Comments

  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    What is 'some power'?
    What kind of thermostats?
    The lights should be on or off, not flashing.
    steve
  • kilgore
    kilgore Member Posts: 4
    >What is 'some power'?
    1.5V

    >What kind of thermostats?
    Honeywell T822K1018

    >The lights should be on or off, not flashing.
    All of the zones flash or seem to be off.

    Thanks.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,816
    edited January 2022
    If the lights are flashing, I can think of a scenario where this can happen. There is an electric wire that is shorting out. The thermostat calls for heat and the valve opens, then the end switch closes. At that time a short or improper circuit happens and all power is interrupted causing the valve spring to close the valve and open the end switch. All the lights go out. When the end switch opens, the short or improper circuit is disconnected. The lights come back on and the valve(s) open again. Then end switch closes and the cycle repeats.

    How long is the on and of flash? Is the light on for 1 second, 3 seconds, longer? How long do the lights stay off? A video may be helpful. You can use YouTube. I posted a video on facebook and pasted the link in my comment because I did not have a youtube account at the time.

    The end switch wires are the red ones. Could a wire going thru a metal opening have some insulation that has chafed away causing the improper or short circuit.


    Just a thought.

    To check this out, disconnect one red wire at a time until the problem is resolved. That last wire will lead you to the culprit.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • kilgore
    kilgore Member Posts: 4
    Both red and green lights flash in unison a bit faster than once per second. They flash until I manually open the valve and the zone warms up. All 5 zones behave this way.

    None of the red wires on the valves are connected to anything -- seems odd to me based on what I have read, but that is the way it is and seems to have been that way for 10 years. Ends of the wires are stripped and none are twisted or deformed in a way that would suggested they were ever connected to anything.
  • SteveSan
    SteveSan Member Posts: 234
    @kilgore Please give us a call 401-942-8000 and ask for tech support. Please be in front of the control when you call and if you have a multi-meter that would be useful so we can take some readings. You can also disconnect the t-stat wires from the zone on the ZVC control that is giving you the issue and then jump the R-W to see if the LED goes solid instead of flashing. I've also attach a wiring diagram for your Honeywell V8043.
    kcopp
  • HomerJSmith
    HomerJSmith Member Posts: 2,433
    edited January 2022
    This may help. Sequence of operations:

    When the Honeywell T822 calls for heat, the bi-metal sensor closes a set of points. 24 Vac goes from the taco T connection to the thermostat back to the taco other T connection and makes a circuit. The circuit closes a relay on the taco board, let's say zone 1 relay. When the relay closes 24 Vac power, coming from the taco transformer, goes thru the taco zone 1 contacts # 1-2 to the honeywell zone valve thru the yellow leads on the honeywell. This energizes the zone valve motor which moves a lever that closes a micro switch in the zone valve. The micro switch is connected to the red leads which goes to the taco zone 1 # 3-4 connections which turns on the boiler and circulator and also turns on the red led lite for zone 1, solid red. That red led means the zone valve is open.
    Check your wiring. You have 4 wire zone valves, two yellow and two red wires.

    Make sure that any slide switches like mode or slave is set to normal and master.

    If you turn down zone 1 thermostat and jump the taco TT screws for zone 1, the t-stat led will lite and when the zone motor closes the end switch, the red led will lite.

    I suspect that the installer wired the the four wire honeywell zone valves as a two wire zone valves, omitting the end switch, that's why the red wires on the zone valves are not connected. You will probably find that the taco zone 1 #1-2 screws are connected to the yellow honeywell wires and there is a jumper between the taco zone 1 #3-4 screws. If so, wire it correctly. I'm sure you could send us a pic of the Taco Box.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,816
    SteveSan said:

    @kilgore Please give us a call 401-942-8000 and ask for tech support. Please be in front of the control when you call and if you have a multi-meter that would be useful so we can take some readings. You can also disconnect the t-stat wires from the zone on the ZVC control that is giving you the issue and then jump the R-W to see if the LED goes solid instead of flashing. I've also attach a wiring diagram for your Honeywell V8043.

    Steve, That is great that Taco will take this @kilgore's call and help him thru the issue. I believe his valve actuators are the ones with the red and yellow wires, not the terminal block type you illustrated. This can be confusing to someone not familiar with the internal wiring of these valve actuators

    This adjustment should help
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    HomerJSmith
  • kilgore
    kilgore Member Posts: 4
    Hey All, thanks for all the helpful comments. I was able to wire up the red wires from the zone valve into the Taco controller as described above. Previously all zones had a jumper b/w the 3-4 slot of the zone valve on the controller. This change eliminated the flashing red for each zone, now only the yellow light flashes when the zone is calling for heat but the zone valve did not open. Manually opening the zone valve did not engage the boiler/circulator as it had when the jumpers were in place. Replacing the jumper on zone 1 allowed the hot water to circulate in the zones when manually opened -- this was the case for all zones even if zone 1 was the only one with the jumper.

    Was planning on calling Taco support today but they are out for the holiday, will call them tomorrow.

    Attached is a picture:

    Thanks again for all your help.
  • hot_rod
    hot_rod Member Posts: 22,100
    Manually moving the lever on the zone valve doesn’t always “make” the end switch. It depended on the brand of valve.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream