Hello, I'd like to install an Aprilaire 700 (not 700A or 700M) on my communicating Comfortmaker G9MVT1002120A furnace (with Comfortmaker CCA948GKA outdoor AC) in automatic mode. My thermostat is the Observer TSTAT0101SC.

The Humidifier recommends the wiring schematic copied below (I used someone else's image, but the wiring is the same as what came with mine).

This is the wiring I currently have.

Thermostat------Wire------Furnace
DX+ -----------green------A
DX- ------------yellow-----B
C --------------white------C
R --------------red--------D

The furnace has a strip with these terminals (nothing connected to them) W2 Y1 DHUM G COM24V W/W1 Y/Y2 R. There is a HUM in the middle of the board with nothing connected.

Should I be connecting my Aprilaire model 60 humidistat to the unused strip in the furnace (R to R, C to COM24V, W to W/W1, ignore G because I'm using the cold water supply)?

Alternatively, is there a way to connect the humidifier to my current thermostat? It knows the outdoor temperature and indoor humidity?

Thank you

 

For this furnace, you won't need the Aprilaire humidistat, you wire the humidifier right to the furnace since the thermostat you have has humidity control.

So you will wire one side of the solenoid valve to HUM on the board, and the other side to C.

 

Hi Jay11J,

Just want to make sure the wiring is as simple as it seems.

1) wire one side of the solenoid valve to HUM on the board, and the other side to C (on the board).
2) plug humidifier plug into 120VAC outlet.
3) do not use Aprilaire humidistat, Aprilaire transformer, or Aprilaire outside temperature sensor?


Thanks

 

That is correct, and you may need to go into your thermostat set up menu to let it know it has a humidifier on it now.

 

Hi Jay,

One more question. The Observer thermostat booklet says

"Most fan powered humidifiers produce internal 24VAC in order to energize upon a switch or contact closure. For this application, a 24VAC N.O. Isolation Relay (DPST) MUST be used to prevent mixing the internal humidifier power with the indoor equipment transformer. Applying 24VAC isolation relay coil to furnace or fan coil HUM and COM terminals will allow the Observer Control to automatically energize the HUM output during a call for humidification. The N.O. relay contacts will be used to energize the humidifier."

Should I ignore this since I am not using the transformer that came with the humidifier?

Thanks

 

The Aprilaire low voltage wire is not "HOT" like Honeywell units, so you will not need a relay or transformer.

 

K got it installed. Temp is set to 75 and hum is set to 45%. Its pretty much stayed between 40% and 45% which is an improvement from 30%-40%. I live in northern NJ. Here is a video of my setup. any suggestions?

https://www.youtube.com/watch?v=2Q-hk6VZ4bg

Thanks for your help installing it.

 

Looks fine to me!

45% is pretty high! You don't need it that high, and you may have water around the window edges.