Wiring Aprilaire 700 w/ American Standard Freedom 90 Comfort-R

I'm completely new to any HVAC work, but thought I'd try tackling the installation of a Aprilaire 700 humidifier on my American Standard Freedom 90 Comfort-R. I'm struggling with the wiring of the humidistat. The install instructions that came with the humidifier indicate that I should wire the 'H' terminals to the humidifier and then the 'R' and 'C' terminals to the furnace accessory terminals. According to the Installer's Guide for the furnace, "an optional humidistat is to be connected between 'R' and 'BK' and the factory installed jumper 'R' to 'BK' on the circuit board must be cut if optional humidistat is used." So, my thought was that what I needed to do was cut the factory jumper between 'R' and 'BK' on the circuit board and then connect the 'R' and 'BK' terminals to the 'R' and 'C' terminals on the humidistat. But, apparently I'm not reading something correctly since after doing this I don't have power to the humidistat. Am I mis-reading something and this is not the correct way to do it? Any help would be appreciated.

 

Hold off on everything till I post back tonight.. I need to get ready for work here soon.

Undo the wire before any damage may be done.

 

Yeah, when it wasn't working and I couldn't figure out why I put the wiring back to how it was and don't currently have the humidistat connected to anything. I'm waiting until I better understand what I'm doing wrong...

 

Ok, for your power, you go down to the board's R and C. for humidistat's 24 volt.

Then in the junction box on the left side of furnace is where there is a wire inside labled EAC and HUM.. Put an out let on the side of the furnace and wire one of the hot wire from outlet to HUM. then Com to the white wire.

Then wire the humidfier's brown wire to H on the humidistat..

Hope you did not cut the jumper wire on the board. The BK is for the humidity control in A/C set up. Your humidistat will not work with this.

 

Ok, I see the 'R' terminal on the board, but I don't have a terminal labeled 'C' on my board. In the furnace installer's guide it references the terminal labeled 'B' as 'B/C', so is that one I want to use for 'C'?

 

Yes, You need to use the B/C for your com.. Should of know that.

 

Ok, that's what I thought, just thought I'd confirm since I misread things the first time :-) So, the R/C connections are going to give full time 24V power to the humidistat and then the outlet connected to HUM will only provide power to the humidifier when the furnace is providing heat. Which would mean the humidifier will run when the furnace is providing heat and the humidistat is telling it that it needs to raise the humidity level, correct?

Today I'll figure out what I'm going to do with the junction box. There is already an outlet there that they put in when they installed the furnace, but that is being used for a small water pump that they also installed since there isn't a floor drain close to the furnace. I'll have to look and see which wires they were using for that and then probably install a larger junction box to accommodate having 2 outlets and the switch.

 

On that outlet, you can cut the "bridge" between the hot side, and then just wire that part that is not wired to HUM. save the head ache of putting two outlet box on.

 

It doesn't have a standard dual outlet receptacle. It has a combination single outlet and switch in a single gang j-box. The switch turns power off to the furnace, so it's always left on. Not sure if that switch is required or if I could just get rid of the switch and replace it with a dual outlet receptacle and cut the bridge like you had suggested?

 

Switch should be there for service... Or at last move it up with in reach for service tech to shut down the system when service is needed.