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# Zone Valves to a 40 volt Transformer?

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JimX
JimX Member Posts: 12
in Radiant Heating
I have four zone valves on my 4 zone hot water boiler, with a 40 volt transformer. one zone was added and the valves have been erratic ever since. I have read somewhere, that 3 taco valves are the max that should be on a system with a 40 volt transformer. Is this true?

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  • heatboy
    heatboy Member Posts: 1,468
    edited March 2010
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    I assume....

    ....we are working with the 570 series Taco ZV? And that they are wired direct to the thermostat without a relay (i.e. ZVC404)? Has anything else changed besides just adding a zone (new thermostats)? Have the thermostat anticipators been matched to the 570 amp draw? Sorry for all the questions, but I don't know what eratic you are referring to. Theoretically, the valves could be pulling 96 VA if they are all trying to open simultaneously, which almost never happens.



    Direct wired, I prefer a 50 VA for 4 valves, but in the ZVC404 relay there is a 40 VA for 4 valves.  I believe that is due to the way the circuit board handles the draw.
    heatboy



    The Radiant Whisperer





    "The laws of physics will outweigh the laws of ecomomics every time."
  • JimX
    JimX Member Posts: 12
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    570's

    Yes they are 570's and they are wired direct direct to the thermos. I have to confess I don't know what a thermostat anticipator is. Somtimes a valve will not open when when the thermostat is turned up if I push the valve to manual then back to auto it will work. It is not always the same valve. All of the heads have been changed. I still have the problem occasionally.
  • heatboy
    heatboy Member Posts: 1,468
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    The thermostat......

    .... can make a big difference.  If they Honeywell T-87 (round, mercury tube)  the anticpator is inside.  Pull the outer ring and it's on the bottom of the stat.  The dial has numbers and the pointer should be to the left at .9 or 1.0.



    If it a digital thermostat, make sure it is battery powered and doesn't rely on 24 volts for it's power (unless there is a resistor across terminals 1 & 2 of the zone valve.



    A 40 VA transformer could be the issue, especially if it has some age on it.  A 50 VA transformer would be better..
    heatboy



    The Radiant Whisperer





    "The laws of physics will outweigh the laws of ecomomics every time."
  • JimX
    JimX Member Posts: 12
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    Anticipators

    The anticpators were not in the position that you said they should be . I moved them there and am ordering a 50 volt transformer. Iwill see if that helps.

    Thank you
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