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Hydrostatic 3250-Plus C wire

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jocoo26
jocoo26 Member Posts: 6
in Thermostats and Controls

Hi. Like similar threads on here, I’m trying to add a C wire to my 2-wire system. I don’t have a 24v transformer anywhere to tap off of, and while I have no problem adding a transformer to give myself a C wire I’ve read a few threads that mention needing a relay. So my question is, do I need a relay? If so, my only question would be, which wires are used for the load? I have added diagram and pictures for reference. Thanks

IMG_1056.jpeg IMG_1062.jpeg IMG_1063.jpeg IMG_1057.jpeg IMG_1058.jpeg IMG_1059.jpeg IMG_1060.jpeg IMG_1061.jpeg

Comments

  • 109A_5
    109A_5 Member Posts: 3,456
    edited December 22

    The relay helps everything play nicely together. The relay coil is the load the thermostat sees, the relay contacts control the Hydrostat 3250.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • jocoo26
    jocoo26 Member Posts: 6
    edited December 22

    Perfect. That is totally doable. Before I install it like that, is it possible to use this product? If so, could you break down the wiring for me?

    IMG_1064.jpeg

    https://a.co/d/7WTkSB4

  • 109A_5
    109A_5 Member Posts: 3,456

    I would say no. Both the load (Red) and the switching contacts (Orange) are on the 120 VAC side of that device. This device is for using a 24 VAC powered device that switches 24VAC with 24VAC wiring to ultimately control a 120 VAC device.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • 109A_5
    109A_5 Member Posts: 3,456

    Often transformer is near the thermostat unless all 3 wires are run through the building. The relay could be with the thermostat and transformer or at the boiler.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • HVACNUT
    HVACNUT Member Posts: 7,233
    Screenshot_20251222_055121_Samsung Internet.jpg

    This is what you want.

    R (Red 24v) on a 40 va transformer to R on the thermostat.

    C on the transformer to C on the thermostat and White/Yellow (Comm) on the RIB relay.

    W on the thermostat to White/Blue on the relay.

    Yellow on the relay to one thermostat Black on the boiler.

    Orange on the relay to the other thermostat Black on the boiler.

    As a side note, I see 2 circulators. The Hydrostat seems to be the zone that's getting the smart thermostat. Does the other zone use a line voltage (120 volt) thermostat, because I don't see a switching relay for it. If that second zone is calling, there's nothing to shut off the circulator if boiler temperature drops below the Low limit setting. And that's why you don't have enough hot water in winter.

  • jocoo26
    jocoo26 Member Posts: 6
    edited December 22

    So I would still need a transformer with this relay? The one I pictured was a transformer and relay in one, which was why I was asking about it.
    Also, when you say “black on the boiler,” where do I find those?

    And I’m not sure, but I’ve never run out of hot water in the winter

  • HVACNUT
    HVACNUT Member Posts: 7,233
    https://forum.heatinghelp.com/discussion/comment/1878600#Comment_1878600

    Yes, you will need a seperate transformer. The one you show has line voltage contacts. You need low voltage contacts.

    Sorry, no black wires. Different thread. Orange and Yellow go to TT on the Hydrostat.

  • jocoo26
    jocoo26 Member Posts: 6
    edited December 22

    Do you know if they make a transformer/relay all-in-one similar to what I posted? If not, I will just use a regular 24v transformer.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,591
    RIB RELAY & TRANSFORMER FOR NEST.pdf
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,591
    RIB RELAY & TRANSFORMER FOR NEST.pdf

    Here is a diagram you can use.

    Yellow and orange on the rib relay would go to T & T on the hydrostat.

  • jocoo26
    jocoo26 Member Posts: 6

    That’s great. Thanks.
    Is there an all-in-one transformer/relay that you know of that can be used?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,591

    You can get what Honeywell calls a fan center which is a relay and transformer in one.

    The rib relay is about $20, a transformer is about $30 maybe. So a fan center is about the same $. I like the rib relay because it has an idiot light to tell you the relay is calling. A fan center complicates thing but thats just me.

    You mount a 4" square box bring 120v to it. Mount the rib relay and the transformer on the box bring the thermostat wires to it and two wires to start the boiler and your done.

    See the attached fan center

    R8285A1048-Install.pdf
    HVACNUT
  • 109A_5
    109A_5 Member Posts: 3,456
    edited December 23

    Products like the Taco SR501 switching relay (and others) have their own enclosure, so no exposed wires. There are extra features so you have to wire it up correctly.

    image.png image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • jocoo26
    jocoo26 Member Posts: 6

    I will do the research on both of those and decide which way to go. Either way you provided me with the info I needed so thank you to everyone. Happy Holidays

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,591

    Taco SR501is good but more $$$ easier to install though.

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