Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.

If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
Need to contact us? Visit

Caleffi Z-One valves.

ChasManChasMan Posts: 459Member
Is there supposed to be a resistor on these somewhere? I have five of these, two had failed end switches and were replaced with the newer reed / magnet. I'm still surprised that the other three microswitches are working. Well, no not really I am being sarcastic. I replaced the Burgess switches with Honeywell switches so instead of a cheap knockoff you get real wiping with real silver so they are ok. But I read somewhere that the reed switch heads should have come with a resistor to limit current through the end switch. My heads did not come with a resistor. Does anyone know if it is needed and what value it should be?


  • hot_rodhot_rod Posts: 12,608Member
    If you are using a Caleffi Z-one with the reed switch type end switch, the resistor is built (molded in ) to the switch now. It has been for several years.

    We also eliminated the need for a resistor when using power stealing t-stats.

    Read the directions on other brands of relay boxes, some still require you add a resistor to "shed" away that voltage with power stealing stats wired with two wire.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • ChasManChasMan Posts: 459Member
    Thanks again. I bought these five just before the switchover, I had two go within a month so I bought two new heads with reed switches and I put new microswitches in the other heads. Not one problem in the last 10 years so I will just let sleeping dogs lie for now. I'm not using power stealing stats just a zone control. I Like these valves a lot. Just wish I could get the label upside right but you have been hearing that for years I am sure.
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!