Connecting Aprilaire Manual Humidistat


  #1  
Old 05-17-24, 11:08 AM
D
Member
Thread Starter
Join Date: Mar 2001
Location: Connecticut
Posts: 712
Upvotes: 0
Received 0 Upvotes on 0 Posts
Connecting Aprilaire Manual Humidistat

I tried searching for this, and I think I've found the answer, but I want to be sure. We have an Aprilaire 400 with manual humidistat that needs to be connected to a Maytag furnace. Do I connect the input lead of the humidistat to R on furnace, and then output from humidistat to white wire on humidifier. And then yellow lead from humidifier solenoid back to C terminal on furnace? Thanks.
 
  #2  
Old 05-18-24, 01:28 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 65,746
Received 4,116 Upvotes on 3,696 Posts
R is always live 24v. If you used R.... the humidifier would never shut off.
Use W and C instead. W is active during heating.

The circuit is AC so order of connection or wire color is not critical.


 
  #3  
Old 05-18-24, 01:35 PM
D
Member
Thread Starter
Join Date: Mar 2001
Location: Connecticut
Posts: 712
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thank you. And on the actual humidistat, would it be attached to the 24v and C terminals? There are about 8 different connections including I+ and I-. And 24V and C.
 
  #4  
Old 06-20-24, 02:01 PM
D
Member
Thread Starter
Join Date: Mar 2001
Location: Connecticut
Posts: 712
Upvotes: 0
Received 0 Upvotes on 0 Posts
I must be dense. I'm still not quite sure. I found an Aprilaire diagram where I would wire from my furnace board as follows W to 24v on humidistat and C to C. It then shows wiring humidifier to H and H on humidistat. I have the manual one where I have to turn the dial based on outdoor temp. It has a resistor where the outdoor sensor would go. My water valve solenoid wires, which are both yellow, would just wire to H and H? I don't need a transformer for it like I've seen in other diagrams? thank you
 
  #5  
Old 06-20-24, 03:22 PM
F
Member
Join Date: Jun 2024
Location: United States
Posts: 10
Upvotes: 0
Received 0 Upvotes on 0 Posts
is this the humidistat you have?


 
  #6  
Old 06-21-24, 04:24 AM
D
Member
Thread Starter
Join Date: Mar 2001
Location: Connecticut
Posts: 712
Upvotes: 0
Received 0 Upvotes on 0 Posts
Yes. the diagram doesn't show the connections inside. I just connected (from furnace) W to R and C to C. I then connected humidifier leads to H and H. With heat on, when I rotated knob to test, it did start. So I guess it's wired correctly.
 
  #7  
Old 06-21-24, 06:46 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 65,746
Received 4,116 Upvotes on 3,696 Posts
Dave..... you put manual humidistat in the title.
That is an automatic humidistat.

You need three wires from the furnace to the humidistat and two wires to the humidifier.

If this is not your humidistat.... post its model number.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: