Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.
If our community has helped you, please consider making a contribution to support this website. Thanks!

relay trane furnace

Options
creger.robert
creger.robert Member Posts: 116
in A-C, Heat Pumps & Refrigeration

Tuc0808942a1 trane furnace does anyone have a wiring diagram for this unit

I need a relay 21d131200p22

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,612
    edited August 7

    How old is this furnace? I dont see that model number in the dealer database. The only information I have that is close to your model number is this https://www.trane.com/WEBCACHE/18-CD19D5-1_01011993.PDF

    I'm not sure that you can open this link but this is the front page of the manual: Is the model number possibly TUC080C942A1 ? look closer at the rating plate/sticker.

    image.png

    Does this look like your furnace?

    Edward Young Retired

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

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,612
    edited August 7

    A little more searching found that there is no relay with the part number 21d131200p22 on that furnace. can you take a photo and post the photo on this forum. I found that this furnace uses a control board that may be called a fan timer or an integrated furnace control. if there is an additional control with that part number added to operate the system in some way, it was not supplied by Trane or they do not use that part number to identify it.

    image.png

    Edward Young Retired

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

  • 109A_5
    109A_5 Member Posts: 4,314
    edited August 7

    This relay was listed for a Trane TUC080B942A1

    image.png

    ebay has this listing; Trane Rly01172 Rly1172 Control Relay 21d131200p22 WW24X0231

    image.png image.png

    Supplyhouse.com

    image.png

    https://www.supplyhouse.com/Trane-RLY01172-Fan-Relay-230V-16A-SP4T-24V-Coil

    It looks to me like it is a modified DPDT relay not SP4T. More like a Single Pole Double Throw with a second set of contacts and there is also an extra wire jumpered to one of the contacts, Odd.

    So one armature or Single Pole, N.C. has 3 wiring connections (via 2 contacts) and N.O. has only 2 wiring connections.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    EdTheHeaterManPC7060
  • 109A_5
    109A_5 Member Posts: 4,314
    edited August 7

    This relay seems kind of specialized, probably not a DPDT, however I'm not convinced SP4T is the best description either.

    image.png 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: 4,314

    Make sure you get the correct relay that matches your original one. As an example it appears the part number on the box is the same but the relay looks different.

    image.png image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,612
    edited August 7

    Great find by @109A_5

    Here is the link to the wiring diagram. https://elibrary.tranetechnologies.com/americanstandard/pages/viewers/pdf?projectKey=5faea30aa9c1c400010c44f8&itemKey=5fc8790163152600019f83dd

    If you cant open it because you must log in, I will copy each of the 4 pages and post them here shortly.

    I think this is your wiring diagram.

    image.png

    looks like there are a lot of white wires with numbers to determine which one is which. Trane does that on commercial stuff a lot. I didn't realize they did it on residential stuff. I think this is from the 1990's. I didn't work on many Trane or Am Std residential until after 2008.

    Hope this helps!

    Edward Young Retired

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

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,752

    The way that relay is drawn in the diagram above that @EdTheHeaterMan posted is kind of wierd.

    It is basically a DPST relay with 24 volt coil. 1 pole is NC and 1 pole is NO.

    The relay coil gets powered from G on the stat and closes the NO contacts to run the blower on high speed.

    The heating contacts on the relay are locked open when G calls which is normal.

    During heating the relay is not used except the power is run through the NC contacts. The TD relay get powered when the gas valve is powered to start the fan after a delay or the fan is started from the fan switch in the plenum.

    I don't know what the wire to terminal "F" is or what the two wires (the other end of wire "F") and the neutral that says 'See note 5" is for. maybe a humidifier?

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,612

    Here is the 4 page service fact sheet from Trane

    image.png Screenshot 2026-08-07 at 11.16.51 AM.png Screenshot 2026-08-07 at 11.16.36 AM.png image.png

    Edward Young Retired

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

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,752

    Ok. Note #5 is for an electronic air cleaner. Don't know why they have the double contacts on each pole, one set of contacts would do the same thing.

    Any 24 volt relay with contacts large enough to handle the blower motor will work. Double Pole single thrown with 1 set of open and one set of closed contacts or use two relays

Categories