Humidifiers and Dehumidifiers - Generalaire 900 Bypass Humidifier relay

I bought a Generalaire 900 Whole House Bypass Humidifier and it will be installed to a Goodman furnace gmv91155dxa Gas Furnace and heat pump. The furnace has 24 volt connections on the B1809927 control board for humidifier but I have a question about that. Since it is variable speed do I need to use a 24 volt current sensing relay such as the Generalaire GA50 as well for it to work properly ? (there is a 5" brown lead wire off of the pressure switch already) the info that came with the humidifier shows the relay Can send pics if needed thanks

Honestly, I've never wired it up to an A50 relay on a Variable speed system, so I don't know if it will work or not??

The Brown HUM wire will only power up when the gas heat is on... so since you have a heat pump, you may have to wire a transformer to the EAC on the board of the furnace. EAC will power up any time the blower is running.

Thanks for replying. I have a B1809927 BOARD and it has both 115 volt and 24 volt Hum connections. You are saying to use the EAC connections. Is that because the Hum connections only energize with the gas and not the heat pump? Is there a way for me to insert pictures as attachment to show you the info that I have? I have the schematic from the board as well as the instructions from the humidifier. It clearly shows the use of the relay with a variable spped blower but I just thought since I had the Hum connections on the board maybe it wasn't necessary. Also would hot water use in humidifier increase the efficiency? Thanks hum...
Install Manual. (http://images.xspond.com/items/11/8556/408_900.pdf)

waterheaterman : photos : B1809927S- powered by SmugMug (http://www.waterheaterman.smugmug.com/gallery/1181121#55182265_wNRUu)

TYou are saying to use the EAC connections. Is that because the Hum connections only energize with the gas and not the heat pump?
That is correct. EAC will power up any time the blower runs, and the HUM only comes on when the gas valve is on.

It clearly shows the use of the relay with a variable spped blower
I don't see it on the manual? No need for one since EAC will cycle on and off

Also would hot water use in humidifier increase the efficiency?
Yes, for a heatpump the air flow is not not enough to help with the humidity, so the hot water will add more capcity for you.

I don't see it on the manual? No need for one since EAC will cycle on and off

yes in the Generalaire instructions it says at the top paragraph... when wiring into a multi-speed blower circuit see step 7D
http://images.xspond.com/items/11/8556/408_900.pdf

Also shown in 7D is the 5" brown lead wire that comes off of the multi speed blower motor I think I incorrectly called it a pressure switch before).
The GMV9 manual says that the brown wire(24 volt)," is powered anytime the pressure switch is closed". And the HUM (115 volt)terminals are energized whenever the induced draft blower is energized".

Would the brown wire not be used if the EAC connections are used?
And if the EAC is used then I wouldn't I need to install a ON/OFF switch so the humidifier would not come on during the summer when the blower is used for the A/C?

I thought but maybe incorrectly that using the board HUM connections would simplify things. What would I do if I had A EAC?
Thanks for your help I know this is getting a little involved but just want to get it right.

I wish I could simply attach pictures rather than give URL's to look up!

when wiring into a multi-speed blower circuit see step 7D
Your furnace is a variable speed system, a multi-speed blower is a "Fixed" speed.


And if the EAC is used then I wouldn't I need to install a ON/OFF switch so the humidifier would not come on during the summer when the blower is used for the A/C?
A switch is not needed.. As long your have the humidistat set to "Off" in the summer, you will be fine with out it.

I thought but maybe incorrectly that using the board HUM connections would simplify things.
if you didn't have a heat pump set up, (Unless you don't want the humidifier to run) we would of wired it to HUM.




What would I do if I had A EAC?
You can piggy back the hook up.... Do you have one?

You want to wire it as shown on 7B



I wish I could simply attach pictures rather than give URL's to look up!
The pix needs to be hosted on a photo host site like imageshack.us, or yahoo.

Your furnace is a variable speed system, a multi-speed blower is a "Fixed" speed.
Thanks for clarifying that.

A switch is not needed.. As long your have the humidistat set to "Off" in the summer, you will be fine with out it.
So wire it up like 7B minus the on/off switch and get that function from the humidistat.

if you didn't have a heat pump set up, (Unless you don't want the humidifier to run) we would of wired it to HUM.
So wire to EAC since I have heat pump.

You can piggy back the hook up.... Do you have one?
No just curious, I have honeywell F100F Media Air Cleaner and I want to add UV light later what is your thought on those?

Thank you so much for your help Jay11J.

No just curious, I have honeywell F100F Media Air Cleaner and I want to add UV light later what is your thought on those?
I have the Media as well, and UV on my furnace. My UV is plugged into the regular outlet, so it's on all times. I think they work, some don't think so. Since I've had it my colds are almost down to none last couple of years.

I have been busy and just gotten around to installing the humidifier. but I still need some help please. I wired my humidifier to the 24 volt transformer which is connected to the EAC. (works) but how do I get constant 24volts to the humidistat?
Can I take it off the 24 volts which go to my seperate thermostat?(located right next to each other in family room) If so can I just use small jumpers or new wire run back to the furnaces 24 volt transformer which IS constant?
I guess it might be easier to buy new thermostat that does it all??? But they are $$$. thanks

You could run a wire over to the t-stat and piggy back onto R and C (always hot)

If C is not hooked up at your t-stat, then you need to hook that up at the stat, and at the furnace.

So wire it as shown on 7B, and run wires from thermostats R & C to humidistats AC N & AC L (piggybacked with wires to 24 volt transformer which is powered by 115volt EAC (for constant hot for display and sensor)?

the two different sources of 24 volt power (1 SWITCHED from EAC/transformer/humidistat and 2nd CONSTANT from furnace/ thermostat will not damage the humidistat or anything else? thanks I thought this would be easier since My furnace had the HUM connections and the brown lead wire from the low pressure switch but it only supplies 5 volts of power.

the two different sources of 24 volt power (1 SWITCHED from EAC/transformer/humidistat and 2nd CONSTANT from furnace/ thermostat will not damage the humidistat or anything else?
This second transformer(Constant power), what is this for?

You could run a wire down to that if you want, but in my last post here, you can piggy back on the t-stat R and C.

the constant power is for the humidistat to function as it only comes on when EAC is energized. I wired everything up as in 7B and the display worked but the solenoid would not open. You were right the brown wire only energizes with the auxillary or GAS heat (below 30 degrees) right now I have the solenoid hooked up directly to the solenoid just to get it to work but 7B illustration did not work.

Do you have a jumper wire between AC N and HUM?

I thought you wanted the display on all times, and then have the HUM power up only when the fan is running?

On 7B, the display will only power up when the fan is running.