Caleffi Z-one actuator failures

Discussion in 'HVAC Heating & Cooling' started by seattle_steve, Jan 5, 2012.

  1. seattle_steve

    seattle_steve New Member

    Jan 13, 2011
    Seattle, WA
    I had a radiant heating system installed just over two years ago (Munchkin boiler to radiant baseboards). I have had 3 failed zone valve actuators during this time. They were all the Caleffi Z-one Z151000 model. The mechanism continues to work (it opens the valve when the thermostat tells it to), but the boiler doesn't fire up, which leads me to believe some electronic part in the actuators has failed (it doesn't seem to be passing on the message to the boiler to start up). I know it's a problem with the actuator and not the boiler because when I replace the actuator with a new one, everything is back to working as expected.

    I'm wondering if anyone else has had a problem with these actuators? Or if not, any ideas why they might be failing?

    There's no clear pattern in the failures: 2 failed right at the beginning of the heating season (after being off for several months during summer); the third one has just failed mid-season.

    The installer has said that there is a 2-year warranty on these actuators, so I'm pretty much SOL as far as they're concerned. (Actually, I may be able to get them to replace the one they installed last year, since it should still be under warranty.)

    Second question: To replace the actuator it is easily removed from a brass fitting that (I assume) contains the actual valve. Is this brass valve fitting standard, or will only the Caleffi actuators fit? (In other words, I'd like to try a different brand of actuator without having to drain the system, cut out the valve, re-sweat a new valve, etc.)

    Here's the actuator:

  2. hr rohr

    hr rohr In the Trades

    Jan 9, 2012
    SW Missouri
    Maybe I can help. A little info please... Are the valves powered via a relay box, maybe Taco, Argo, B&G? What type of boiler is it running? Can you send me the date code? Have you contacted the dealer or rep locally?

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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    These things typically have an 'end switch' in them that closes. Are you using that to switch 24vac or 120vac loads? What size is the load? If you are trying to switch more load than the switch contacts can handle, they'll fail relatively quickly. It may be in your switching design and not a failure of the actuator itself.
  5. thegove

    thegove New Member

    Jan 2, 2013
    I too have had three Caleffi z-one switches (z151000) fail in about 5 years. They all failed the same way: Although the motor responds to the signal from the thermostat to open the valve, the control valve does not send the signal to the boiler to engage. The specs for the switch are at In this document, the switch that is failing is called the "auxiliary switch." It is an ultramicroswitch and in my experience, the switch will work intermittently when actuated by hand but does not respond to the pressure applied by the cam in the control unit. The switches are available from Allied for around 4 dollars each. It must be soldered in. Hope this helps
    Last edited: Jan 2, 2013

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