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Honeywell He400a humidifier

rreale
rreale Member Posts: 13
in Thermostats and Controls

I just hooked this up to furnace. it comes with the Humidipro 6202 humidistat.

I am getting no power to the water solenoid. the terminal block on the humidistat has 4 wires connected. R and C from a new separate transformer(not the one on the furnace) There are 2 terminal connections labelled "U" each has a wire connected to the water solenoid. The humidstat gets 28v., but no power ever comes out the 2 wires going to the U solenoid. I called tech support several times, went and got a new humidifier. same issue.

I think the wiring is incorrect but Honeywell said it is fine. I saw on the another forum to run a jumper wire from R or C terminal to one of the U terminals. Any ideas???

Comments

  • mattmia2
    mattmia2 Member Posts: 12,200

    u-u is just a dry contact closure. you have to connect 24vac with one side to the solenoid and the other side through the u-u contacts. that 24vac needs to be switched with the blower or it will call the humidifier constantly.

  • mattmia2
    mattmia2 Member Posts: 12,200

    https://s3.amazonaws.com/s3.supplyhouse.com/product_files/69-27941.pdf
  • rreale
    rreale Member Posts: 13

    So if i move one of the wires under u and move it to r or c, it should work?

  • mattmia2
    mattmia2 Member Posts: 12,200
    edited March 8

    You need power to r and c constantly. I don't know how you have the humidifier itself wired. U-U should interrupt one of the wires from a 24 vac power source that is switched with the blower connected to the water valve.

    one option is to get the constant 24vac from the furnace/air handler between R and C on the furnace and connect the transformer to the blower or an aux terminal so it is powered with the blower

    then connect the 24vac from the transformer which is now switched with the blower to the water valve with one sode being broken through u-u.

  • rreale
    rreale Member Posts: 13

    There are 2 wires from the humidifier. one goes to one of the U terminals on the humidistat and the other wire goes to the other U terminal.

    R and C have power constantly from a transformer that came with the humidifier

    sorry . i dont understand wiring diagrams and electrical speak well.

  • mattmia2
    mattmia2 Member Posts: 12,200

    Let's see if we can break it down better.

    U-U is just a switch. It just turns the humidifier on or odd, it doesn't provide power

    R and C are 24vac power. It should be powered all the time. There will be an R and C on the transformer in the furnace which will always be powered. You can take this power from there by connecting a cable between the r and c on the furnace and the control.

    You need a switched 24vac or 120vac to power the humidifier itself which you will have to get from the furnace. Can you take a picture of the board in the furnace and the schematic of the furnace, usually inside the blower door? There are several ways to do this depending on how your furnace is built.

  • rreale
    rreale Member Posts: 13

    ok, i Have 24 volts to the humidistat delivered from the new transformer that I hooked up yesterday.

    The furnace board has spade connections for humid(hot) and humid(neutral)

    the last pic is the humidistat

    PXL_20250308_205544222.jpg
    PXL_20250308_213412362.jpg
    PXL_20250308_205910324.jpg
  • HVACNUT
    HVACNUT Member Posts: 6,676
    edited March 9
    https://forum.heatinghelp.com/discussion/comment/1847327#Comment_1847327

    So the humidifier transformer's primary (120 volt) side is connected to the Humidifier (120v) terminals on the furnace board? And the 2 Red/Black wires are going to the solenoid? No good. U-U is just a switch.

    Do this. Leave the humidifier transformer connected as is on the 120 volt side.

    Run 24 volt power from R and C on the furnace board to R and C on the humidistat. This will give the humidistat constant power for the display and switching.

    From the 24 volt side of the humidifier transformer, connect Common to one Red/Black wire on the solenoid. Then from 24v/R on the humidifier transformer, connect to a U terminal on the humidistat. The other U terminal connects to the other Red/Black.

    So now there will always be a display at the humidistat. And the humidifier itself will only operate in heat mode when the fan is energized.

    The humidistat is in the return, upstream of the humidifier or bypass?

  • rreale
    rreale Member Posts: 13

    The transformers 120 volt side is connected to a nearby outlet and both u terminals are connected to the humidifier. humidistat and humidifier is on the return side. it is a bypass. i will try what you recommend.

  • HVACNUT
    HVACNUT Member Posts: 6,676
    https://forum.heatinghelp.com/discussion/comment/1847418#Comment_1847418

    Where in the instructions does it say, "connect to a nearby outlet."?

  • rreale
    rreale Member Posts: 13

    Well, it says "install transformer on the outside of a grounded metal junction box". i cheated a little and connected it to a plastic junction box with a ground wire. running the 2 transformer 120v wires to the receptacle terminals inside the junction box.

  • mattmia2
    mattmia2 Member Posts: 12,200

    Here's the easiest way to wire it, combine the wires at the furnace with any existing wires. It just runs off the furnace transformer. It is a very small load. It will run the humidifier before the blower starts on a heat call and stop it when the heat call ends. it will let the pad get wet before the the blower starts and let it dry out between when the heat call ends and the blower stops.

    image.png

    If you want to use the transformer, this is how you'd do it:

    image.png

    There are other ways to do it but these are probably the simplest.

  • rreale
    rreale Member Posts: 13

    ok. will both ways open the water valve if the furnace fan is on but not calling for heat? From April till November I plan to turn the humidistat and water valve to the humidifier off

    thx

  • mattmia2
    mattmia2 Member Posts: 12,200

    If you wanted it to turn the humidifier on whenever the fan is on you would use the second one but use the "eac" terminals instead of the "hum" terminals. I don't think you want that because without the heat from the furnace the humidifier isn't going to evaporate much water so you aren't gaining much humidity and using a lot of water by running it with the blower constantly.

  • rreale
    rreale Member Posts: 13

    Thx. I used the first solution and it worked great

    mattmia2HVACNUT

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