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Adding Zone Valves to Weil McClain HE Boiler

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Mudaero
Mudaero Member Posts: 46
Hey all,

I want to add 2 zone valves (Honeywell V8043E) to an older Weil McClain HE boiler. Currently, I only have one thermostat connected directly to the boiler as shown in the image below...


The wiring schematic for the boiler is this...


And this is one of the wiring diagrams from Honeywell that seemed to match what I am trying to do (eliminating the third zone valve and thermostat)...


I want to use the V8043e valve because I can get it as an NPT body instead of sweat. But looking at the diagram, it seems like the v8043a would be the one I should use. Can any one help me wire the v8043e to my system or give me any advice on how I should proceed? Please let me know if there is anything else I can describe or any information needed. Thanks for looking. I appreciate any help.

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  • HVACNUT
    HVACNUT Member Posts: 5,855
    edited October 2018
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    Figure 16 doesnt show an end switch, which is needed.

    Figure 17 looks like line voltage switching which you can't use with the factory wiring.

    You need 2- 24v zone valves with end switches.

    The black wires that the existing thermostat wires are spliced to are the wires you connect to the zone valves end switches, in parallel.
    Instructions will come with the valves.

    That is a 40va factory transformer so 2 zone valves is fine.

    Checked all other hydronic parts before you drain the boiler. Time for a new air eliminator, PRV, relief valve, etc?
    Solid_Fuel_Man
  • Mudaero
    Mudaero Member Posts: 46
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    Ok, I think that makes sense. I have already changed out the other parts when I made my initial changes to my system last year. I will look for some other zone valves and will most likely come back on this thread to make sure that it will be what I need. Thanks for the help, it is appreciated.
  • HVACNUT
    HVACNUT Member Posts: 5,855
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    @Mudaero

    Rereading my earlier post, I realize I am mistaken about using the "E" zone valves. You can, just not wired as shown in figure 17.

    The end switch wires will connect to the 2 blacks at the boiler.
  • Mudaero
    Mudaero Member Posts: 46
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    Hey HVACNut,

    Would my wiring diagram look something like this below? I realize the control unit might not be the same as mine, but I'm using this image as a generalization. If so, I guess my confusion lies at where the lines from the transformer go to the thermostats, since those appear to be the ones I'm tying the reds to from the zone valve. Do I need to pull new leads from the transformer to go to the thermostats or do I just split off the ones that are there? I also included the wiring diagram for a White Rodgers system as shown in the zone valve instructions since that's what's on my boiler. Again, thanks for your input. I apologize for my ignorance on the subject, but I'm trying to learn everything I can.




  • Mudaero
    Mudaero Member Posts: 46
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    Or do I simply need a new transformer and then wire like the top diagram and have the two reds going into the boiler and connecting to the two black leads?
  • hot_rod
    hot_rod Member Posts: 22,244
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    A zone relay board would simplify all this and prevent mis-wiring.

    You get a fused transformer, indicator and trouble shooting lights. Caleffi and others now have 3 wire connection for power stealing or digital thermostats. A single 2 wire to call the boiler on.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    STEVEusaPAZman
  • Mudaero
    Mudaero Member Posts: 46
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    Thank you for the advice. While I would like to use a relay board, it's just not feasible right now. When I replace my boiler, I will do that, but for this current project, I just want to use what I have.
  • Zman
    Zman Member Posts: 7,572
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    What size is the transformer in the boiler you are connecting to?What is the amp draw of the boiler controls? You need to make sure the transformer has capacity.
    Just by one of these and follow the simple diagram and you won't have to worry about any of that. You can leave it in place when you install the new boiler.
    https://www.supplyhouse.com/Taco-ZVC403-4-3-Zone-Valve-Control-Module-with-Priority
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • HVACNUT
    HVACNUT Member Posts: 5,855
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    It can be wired exactly like the top diagram.

    You dont need a new transformer. The boiler has a typical HVAC fan center control with a 40va transformer.

    Using the top diagram,
    At the 24v side of the transformer, we'll use the top black wire as power. That is designated 'R' on the transformer.

    The bottom yellow wire coming out of the transformer we'll designate as common. 'C' on the transformer.

    It wouldn't be a bad idea to install an inline fuse. 5A.
    Mudaero
  • Mudaero
    Mudaero Member Posts: 46
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    Excellent! That completely clarifies everything for me. I really appreciate your help on this matter. I can't thank you enough.
  • Mudaero
    Mudaero Member Posts: 46
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    Hey HVACNut,

    Just wanted to let you know that everything is working brilliantly. Hookup was simple and your help with the wiring was crucial. Just wanted to thank you again for your assistance.
    HVACNUT