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Taco zone valve

GaryDidier Member Posts: 229
Are there any field tests that can determine if a valve head has gone bad.Thanx, Gary from Granville


  • Which TACO Zone Valve?

    Is it the old "Gold" head (or real old "Green Heads) or the new ESP Black head?

    It is typically if you have 24 volts to the head and the valve does not open the head is bad. There is an adjustment that can be made to the old "Gold"/Green" heads but TACO does not like you to do that.On the old heads with the thermostat calling go across terminals 1 and 2 you should read 24 volts. If not then problem is external (not the zone valve) If you have 24 volts the head should smell like it is burning, and it should get hot. If you have 24 volts and the head is hot and nothing happens then jump out 2 and 3 if the equipment comes on the the end switch is not making in the head and you need a new head.

    I will wait to hear from you as to it being the ESP valve.
  • Justin Gavin
    Justin Gavin Member Posts: 129

    We have replaced a couple of heads on a job that had 26 ESP Valves on it. When it was all done and said it turned out that the valve head was fine. When you solder the body make sure that the ball valve is completely open otherwise solder might run into the ball cavity and prevent the valve from closing or opening completely.

    Good Luck,


    there is now also a version 2 which has supposodly solved all of their previous problems with version 1.
  • andy_5
    andy_5 Member Posts: 20

    Couldn't you also take a continuity test across 2 and 3?If you have 24 volts,and no continuity,then the valve head is bad.Or if you have no continuity across 1 and 2 then the head is bad.
  • GaryDidier
    GaryDidier Member Posts: 229
    Taco gold

    I was referring to the gold series.Thanx for your responses.
    Gary from Granville
  • Joe Mattiello
    Joe Mattiello Member Posts: 703

    Good Afternoon
    You can field test a Taco zonevalve, by measuring the voltage at terminals 1 & 2. If you have 24 volts, the valve should feel warm and you should feel migration of heat. After approx. 1 1/2 min, you should have continuity at terminals Two, and Three. Additionally, for your convenience I have attached a trouble shooting guide. Please advise, if you require additional assistance.
    Joe Mattiello

    Joe Mattiello
    Technical Services
    (401)942-8000 ext.484
    Fax (401) 942-2360
    [email protected]
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
  • J.C.A._3
    J.C.A._3 Member Posts: 2,981
    My Favorite test for Taco zone valves.

    Want to know if the valve has failed? The easiest way is to disconnect the #1 wire for a couple minutes, twist the valve head off of the body and shake it while holding it over your hand. If you find a bunch of brown pelletts coming out of the slots in the head, the valve head HAS FAILED. What could be more simple?

    The brown pelletts are the "driving device" of the valve, that have leaked out of the failed actuator. Give it a try. Always try the voltage test first but when you find it there, give my test a try, then replace the head. Chris
  • Ken D.
    Ken D. Member Posts: 836
    Taco Zone Valves

    Turn t-stat up. Check for 24 VAC across terminals 1&2. If there is power there, wait a few minutes. Feel the manual open lever on the head. The resistance to you moving it should decrease as the valve opens, until the lever goes up and down easily, when valve is fully open. At this point you should begin to get circulation of hot water. If the lever continues to be resistive to movement, the head is probably bad. Very seldom does the valve itself fail.Terminals 2&3 are the end switch to bring on the burner or relay.When the valve is open, these contacts should be closed. This would show as 0 volts across Term 2&3. If valve is open and these contacts remain open, then the internal micro switch is bad. Replace valve operator head.
  • Tigerman
    Tigerman Member Posts: 1
    edited August 2014
    Taco Zone valve

    My experience with Taco zone valves is that the body on the inside is susceptible to rust which prevents the head from functioning correctly. The head will test correctly, however, the valve position will not change. I have used the prescribed antifreeze in the system that helps to prevent rust and add a bit of lubrication, however, even that is not 100% effective.

    I have a 5 zone system and will need to change at lease three of the valve bodies in preparation for the coming winter. Every year I have problems with at least one of the valve. I am thinking of changing them out for another brand, however, I am not sure what is a better brand.
  • johnnienovice
    johnnienovice Member Posts: 1
    I am having a problem with my heating system that my furnace guy has not resolved. We have 4 zones in the forced hot water system. In one of the zones when the temperature set on the thermostat has been reached, instead of shutting off the furnace goes off then back on and repeats this cycle rapidly as many as five or six times before finally staying off. My furnace technician says replace the Taco valve. However, in testing this valve (as instructed on this blog) it seems to be working fine. To me it seems like an electrical problem - the boiler getting a signal to shut down, then restart, then shut down ... over and over. Looking for any tips to help diagnose this.
  • billtwocase
    billtwocase Member Posts: 2,385
    could be the control, but sounds like a power head to me, especially if it is only one zone that is doing it
  • icesailor
    icesailor Member Posts: 7,265
    Well, here's another thing. The valve plunger is sticking. Spray the head and body with Kroil or WD 40. After taking the #1 wire off for 2 minutes as a minimum, take a large pair of water pump pliers and put one jaw on the bottom and the other on the plunger where it sticks through the valve. Squeeze the pliars to operate the valve. Be sure that it works freely. It almost always does. Then, look at the black steel plate that holds the valve piston in place. The end goes up through a hole. If any moisture gets on there, it will cause the piston to bind in the hole. That's what the Kroil is for. Get the hole clean and goop it with Never-Seize. Be sure that you spray the bypass lever inside the power head do it is lubricated on the cam it rides on. When done, you can operate the valve with your little finger.

    When that hole gets restricted, it causes enough resistance to overcome the return spring and if the piston stops in just the right place, it will cycle on and off. Sometimes, it sticks and it never breaks the contact between #2 and #3. Giving you an overheat call.

    I always sprayed those heads when I was near them because if they get tight in the hole with rust, the additional pressure required to overcome the rust will blow the power head. And I've installed hundreds of them.