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Humidifier Wiring - Pros and Cons of various possible options

homeAwayhomeAway Chicago, ILMember

Recently bought an Ecobee3. I pulled out the old wiring (4 wires) and installed a new wire with 7 wires. I now have 5 wires from my E3 to the Carrier furnace, and have 2 additional wires. Everything seems to be working well. I'm now trying to connect my humidifier, and have been reading this site for the last few days. There seem to be a few different configurations, and I'm trying to figure out the Pros and Cons. I'm narrowing down to Option 1 or Option 3, but don't know for sure the advantages of one over the other.

The furnace is a Carrier, model 58PAV90. The humidifier is an Aprilaire 550 Humidifier, evaporative and not powered by any external power source. It is connected to an Aprilaire humidistat (which I am not sure is working - also replacing the solenoid valve as part of this project).

I looked at all the wiring, and here are my observations:

1) Total of 5 wires connected to the humidistat
2) 2 connected to the solenoid valve
3) 2 connected to a transformer
4) 1 connected to a sensor somewhere in the building
5) Transformer wires fed by the EAC terminals on the furnace board
6) Furnace board has the HUM terminal, with nothing connected.
7) The Solenoid has two yellow wires, no polarity indications.
From reading this website, it appears there are different ways to do this:

Option 1:
1) Connect ACC+ to Solenoid1 wire
2) Connect Solenoid2 to the C terminal on the furnace board
With this approach, it appears the Ecobee3 can activate the solenoid and turn the fan on when required, it does not need the Heat to be on. This seems to be the most popular option.

Option 2:
1) Connect ACC+ to Solenoid1 wire
2) Connect Solenoid2 wire to the HUM terminal on the furnace board.
With this approach, it appears the Ecobee3 can control the Humidifier only when the Heat is turned on. I was weary about this because I didn't know for sure if the furnace board would be able to power the Solenoid.

Option 3:
1) Connect ACC+ to Solenoid1 wire
2) Connect Solenoid2 wire to Transformer1 wire
3) Connect Tranformer2 wire to ACC-
4) Keep the Transformer to EAC connections as is

I was thinking of this approach, since I have wires for ACC+ and ACC- available and the Transformer already available. I'm not sure what the advantages are over Option 1 though.

Option 4:
1) Connect ACC+ to Solenoid1 wire
2) Connect Solenoid2 wire to the HUM terminal on the furnace board.
3) Connect ACC- to C terminal
This seems be same as Option 2, with an additional connection #3. I couldn't find what the advantage would be.

Answers

  • homeAwayhomeAway Chicago, ILMember
    edited December 2016

    This isn't turning out well. Blew the control board fuse..... :(

    I started with Option 1. Shutoff the power, connected ACC+ to one end of the Solenoid and C to the other end. I reconfigured the Ecobee3 to a 1-wire configuration and as an Evaporative humidifier. Tried to Test, did not work. Tried the Fan, as well as the Heat, did not activate the valve. Checked all wiring, configuration and tried again, no progress. :(

    I change the configuration to show Steam humidifier, same, no progress.

    So I wasn't sure if it was the solenoid valve itself.

    I shut off the power, connected the 24V transfomer leads (the one that powers off the EAC-1 and EAC-2 terminals). When the fan started, the solenoid was activated, the water started to flow. I shut off the power, ran Option 1 again. This time, the LED on the control panel signaled code 24, which indicated the secondary 24v fuse was blown. After some search, I found the blade fuse and was able to confirm that was the problem.

    I disconnected the solenoid when the Fan was off, is that why the fuse would have blown? I'm going to get a new 3A fuse for the board tomorrow. Anyone know if this is something a home center would carry, or would it be best to go to an automotive store (seems similar to what I've seen in my cars, just bigger).

    However, I'm still not sure why Option 1 did not work. :((

  • kevinmcckevinmcc Member
    edited December 2016

    @homeAway said:
    Option 3:
    1) Connect ACC+ to Solenoid1 wire
    2) Connect Solenoid2 wire to Transformer1 wire
    3) Connect Tranformer2 wire to ACC-
    4) Keep the Transformer to EAC connections as is

    I was thinking of this approach, since I have wires for ACC+ and ACC- available and the Transformer already available. I'm not sure what the advantages are over Option 1 though.

    You would be using the transformer for the Aprilaire and not putting more load on the furnace transformer. If you used option one, that could be why you blew a fuse, too much power draw needed to open the solenoid than is available.

    I actually believe option 3 is more common than option 1.

    I believe the wiring should be as follows.

    1) Connect ACC+ to transformer hot.
    2) Connect ACC- to Solenoid wire 1.
    3) Connect Solenoid wire 2 to transformer neutral.

    homeAway
  • homeAwayhomeAway Chicago, ILMember

    Thank you for the response.

    How do I determine a transformer neutral and a transformer hot on the low-voltage side (assume that the EAC-1 and EAC-2 are line voltage)?

    Does it also matter if I wire to the transformer connected to the EAC-1 and EAC-2 terminals, or should I use an always-on transformer elsewhere? (there appear to be two more transformers on the system - one apparently for the door bell, and one more that I have not been able to figure out yet).

  • homeAwayhomeAway Chicago, ILMember

    I couldn't find the 3Amp blade fuse at Home Depot but found it at a car parts store. It says 32V, I assume it means it will work for a 24V system. I took the transformer out, and could see the markings on the primary, however, nothing but two screws for the secondary, so I could use it interchangeably. I followed

    @kevinmcc said:
    I believe the wiring should be as follows.

    1) Connect ACC+ to transformer hot.
    2) Connect ACC- to Solenoid wire 1.
    3) Connect Solenoid wire 2 to transformer neutral.

    and replaced the fuse. On putting it through the test, the heat as well as humidifier worked!!!

    Thank you very much kevinmcc!!

  • kevinmcckevinmcc Member
    Answer ✓

    Great. Yes 32v fuse will work for lesser voltage, the amps is more important. Need to be as specified. Glad you got it going.

  • I'm pretty sure that Option 1 is just going to waste water. You will have little to no evaporation with the heat off and ask the water will simply run down the drain line. FYI, I love my Ecobees, but when things get this complicated I also love my HVAC service tech..

  • homeAwayhomeAway Chicago, ILMember

    Venture996, I think it's going to waste water either way - I've been down a few times to the basement to check on the HVAC and humidifer, and I hear the water go down the drain pipe everytime the fan/heat kicks in. I let it run for a day, and didnt see the humidity go up a lot. I slowed it down to a trickle, and there is less water being wasted.

    This is a new wick filter. The water seems to go down pretty fast the metal mesh in the wick filter. I'm wondering if there is another type of filter I should consider.

  • homeAwayhomeAway Chicago, ILMember

    It seems I was not the only one looking into this: Water Waste in Humidifiers

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