Taco pump with integrated relay

Options
painterswife
painterswife Posts: 14
in Radiant Heating

We have a 2-zone radiant floor system. Over 20 years old

2 Taco pumps with integrated relay that connects to a 24 volt hardwired transformer. Each pump has a 115 cord that plugs into a wall outlet.

Originally a two wire thermostats for each though we upgraded to smart themostats with c wire transformer.

A person who will not be named tore out some wires and I would like to figure out how to start fresh with a two wire thermostat on one zobe ( hardly ever used) and a new smart thermostat on the other.

Any ideas?

Comments

  • painterswife
    painterswife Posts: 14

    More info to help for the basic two wire thermostat

    Transformer hardwired

    Two wires from pump relay

    Two wires to thermostat

  • SuperTech
    SuperTech Posts: 2,704

    Maybe get a Fast Stat FSCM00 common wire adder kit for the "smart" thermostat. But ideally you should just use a simple thermostat for both zones of radiant. The smart thing to do is set your thermostat to a comfortable temperature and leave it alone.

    The person who will not be named is your husband, isn't it?

  • painterswife
    painterswife Posts: 14

    So simple thermostat.

    How to wire pump with integrated relay

    Hard wired transformer

    Thermostat?

  • hot_rod
    hot_rod Posts: 28,689

    there is not much of a transformer in those zone pumps, it may not cover the t stat load

    IMG_3586.jpeg
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Posts: 12,929
    edited 12:45AM

    Your best bet is to use an isolation relay

    Diagram to follow

    From what I can tell from your original statement, you are NOT using the Priority feature of that relay. You are only using the relay to turn on the circulator motor using a 2 wire thermostat. if that is the case, and your other failure has taken the wires apart, you need ot get back to this stage on both pumps before we can move foreword

    Screenshot 2026-11-09 at 7.39.11 PM.png

    You will not have any wire on the P terminal where the 120 VAC input is located. nothing is connected to R or C on the 24 volt power terminals.

    If you can get there then it is easy to add the Isolation Relay

    Edward Young Retired

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

  • EdTheHeaterMan
    EdTheHeaterMan Posts: 12,929

    Here is what you do when you are back to square one when everything was working with 2 wire thermostats. Purchase one of these Fan Center relay. They are inexpensive for getting both a transformer and a relay in one box.

    image.png

    Then wire it up like this. Now you have a powerful transformer to use for the thermostat.

    If there is already a large enough transformer I might recommend the RIB U1C. Not in this case because there is not a powerful enough transformer for the thermostat(s) and the relays you need to isolate the systems.

    Edward Young Retired

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

  • EdTheHeaterMan
    EdTheHeaterMan Posts: 12,929

    Perhaps I misunderstand this series of statements:

    • So simple thermostat.
    • How to wire pump with integrated relay
    • Hard wired transformer
    • Thermostat?

    Does this mean that the transformer inside the Taco Relay attached to the circulator is not the transformer you are referring to in that third item?

    Perhaps a photo of all the parts you are talking about.

    Edward Young Retired

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

  • painterswife
    painterswife Posts: 14
    edited 2:19PM

    The relay is integrated into the taco pump. It is not the same as in the pictures. It has two wires emerging from the side housing that connect to the transformer to drive the relay when the thermostat calls for heat.

    It is a pump from 2002 aprox.

    The transformer is not part of the pump. It is a separate hardwired transformer ( like the one in the above photo)

    There are three things that need to be wired in the circuit.

    Pump that has two wires to connect to the transformer and thermostat

    Thermostat - two wires

    Transformer

    Power to drive the pump is a 114v plug

  • ratio
    ratio Posts: 4,344

    How 'bout a few pics, so we can see what's going on. Try to get the model # of the pump too.

  • EdTheHeaterMan
    EdTheHeaterMan Posts: 12,929

    Your statement "2 Taco pumps with integrated relay" draws this picture in many professional's mind

    image.png

    However your later explanation indicates otherwise.

    What is the actual part number of the 2 taco circulators. That number can be found on the pump somewhere.

    Screenshot 2026-11-10 at 10.16.41 AM.png

    With that model number, we can identify exactly which pump you're working with. A photograph would also be very helpful.

    Here is a side-by-side comparison of the same pump with two different wiring boxes. The one on the right has a larger box to accommodate the relay.

    I believe you have something more like the one on the left, with only the electrical connections for the pump motor.

    Screenshot 2026-11-10 at 10.28.31 AM.png

    It also appears that you have been struggling with this problem for more than a year. I would like to get to the bottom of this for you. Lets work together to get this resolved.

    Edward Young Retired

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

Categories