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C wire & Aquastat L8148E with 3 zones

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Royals
Royals Member Posts: 13
in Thermostats and Controls
I would like to use 2 NEST thermostats on my boiler. I have a Honeywell Aquastat L8148E. I also have 3 Zones (valves are Honeywell V8043E1012) and will be using a NEST on only two of the Zones

I have currently 2 wires connected to the thermostats, both plain 'speaker' wire not colored wires.

Anyone care to help with getting 'C' Wire to the two NEST thermostats maybe with wire diagram ?
Thank-you
Royals

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
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    Do the zone valves have a separate transformer?
    Do the zone valves use the transformer in the L8148E?

    This will determine where to get the C wire from.
    Never Use The Parts Cannon.jpg

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Royals
    Royals Member Posts: 13
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    I am pretty sure the zone valves have separate transformer, outside the Aquastat, let me just confirm
  • Royals
    Royals Member Posts: 13
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    So Yes i can confirm, there is an extrenal transformer, so from the external transformer, the yellow wire goes near the Zone valves, and is then spliced to the 3 zone valves one of their yellow wires (they have 2 yellow wires on each valve). The blue wire from the external transformer, goes to near the Zone valves and is spliced, to the 3 thermostats wires, then from there on to the 2nd yellow wire on their respective zone valves. The 2 RED wires from the Zone valves then go to Aquastat, one each to T and TV.
    Make any sense ?
    Royals
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    edited October 2022
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    Then the C wire on the thermostat goes the the C of the zone valve transformer. diagram to follow
    Never Use The Parts Cannon.jpg

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Royals
    Royals Member Posts: 13
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    EdTheHeaterMan said:

    Then the C wire on the thermostat goes the the C of the zone valve transformer

    Thank-you , which wire would be the 'C' on the valves that i can connect the Themostat C wire to?
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,852
    edited October 2022
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    C on the valve is one of the yellow wires.
    W on the thermostat is the other yellow wire

    Thanks Jamie. I cleaned up the connections and added "wire nut dots"

    Never Use The Parts Cannon.jpg

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Peter_26
  • Jamie Hall
    Jamie Hall Member Posts: 23,324
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    To add a note to @EdTheHeaterMan 's excellent diagrom (wish i could draw like that) -- there is no connection where the black/yellow vertical crosses the black horizontal...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterMan
  • Royals
    Royals Member Posts: 13
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    EdTheHeaterMan said:


    C on the valve is one of the yellow wires.
    W on the thermostat is the other yellow wire

    Thanks Jamie. I cleaned up the connections and added "wire nut dots"

    Ed: I can't thank you enough. everything working like it should. The diagrams were perfect and I followed them easily.
    You're the best
    Royals
    EdTheHeaterMan

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