Generalaire 1000A humidifier and GFX3 humidistat

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Old 02-07-16, 01:38 PM
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Generalaire 1000A humidifier and GFX3 humidistat

Hi,

Before I melt the board on my furnace, I want to get this wiring right.

Generalaire Wires: 2 red and 2 yellow plus a 110 cord

GFX3 Humidistat:ACL, ACN, HUM2, HUM1, SNSR2, SNSR1

Bryant furnace (Bryant 340AAV) : Per manual board has HUM 24VAC .5A max and Neutral connections

The generalaire manual has four different diagrams and neither look right. My furnace has a GA50 relay in it from an old humidifier, but i am not sure if I need it. I want to do this the easiest way and am not concerned if the humidistat display is powered 24/7. If that is easy, so be it. Any assistance is greatly appreciated.

I have 18/2 and 18/5 wire and a voltage meter and am capable with wiring.

Thanks, Pete
 

Last edited by PJmax; 02-07-16 at 03:17 PM. Reason: added model to text.
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Old 02-07-16, 03:08 PM
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Will you be plugging the humidifier into an always live 120v receptacle ?

You will need a 24vac relay for the furnace control from HUM and C or you can continue to use the current sensing (GA50) relay.
 
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Old 02-07-16, 03:32 PM
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Hi PJ,

Thanks for the response. 110 is live all the time.

I thought I could go straight to the bryant 24v HUM as it is switched on with heat. Is the GA50 to make sure we get no humidifier until the fan turns on?

Ok, let me guess. Sensor to sensor screws on humidistat, That was easy, Reds from humidifier t0 ACL and ACN on humidistat. One yellow from humidifier to hum on bryant, common on bryant to one side of GA50- and other GA50 back to other yellow... Do I win a prize or burn down the house??
 
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Old 02-07-16, 03:44 PM
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No that's it.... you've got it correct.

The only thing you could change is to use a 24v relay controlled by the HUM and C terminals to replace the GA50.

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Old 02-07-16, 03:50 PM
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Great. Since I have the GA50 I will use it but is there any difference in performance? With my proposed connection, will the Humidistat only have a display during heating??
 
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Old 02-07-16, 03:53 PM
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You are supplying 24vac to humidistat on the red wires. The humidistat will always be working and live. You won't get any humidifier action until the blower is on.
 
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Old 02-07-16, 04:14 PM
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Oops

I forgot about Hum1 and Hum2 on humidistat?? your diagram looks good. I will give it a run..
 
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Old 02-07-16, 05:15 PM
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Victory

Thanks for the killer diagram. I declare victory! You are the best.
 
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Old 02-07-16, 05:34 PM
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Oops again

Declared victory too early. I always do that. A curse.

THE humidifier just cut on in auto mode without the heat or fan. I have to see what is going on.

Update: I accidentally hooked what was supposed to be common on the board to EAC, so I had one off board from HUM and one from EAC. Decieving as it says Neutral right under it. Now no way to get the blown 3amp fuse tonite. It will be a cold one.. DO they sell these at home depot?
 

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Old 02-08-16, 06:10 AM
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Got a new fuse

Ok, no one sells these stupid fuses bot got one from an hvac guy in front of a wholesale place. Heat working again.

So I need to reinstall HUM and Neutral/common to board. Can I use the common or "C" on the thermostat bar for the common yellow wire to humidifier since I have no more neutral tabs left on my board?
 
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Old 02-08-16, 10:05 AM
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The diagram I left is IF you use a 24v relay. If you are using the GA50 then there are no connections to the control board.

That 3A fuse should be a standard automotive plastic fuse. Also called an ATC-3.

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Old 02-08-16, 10:14 AM
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Ok

So the induction of the fan on the GA50 sends the signal to open the valve? I will do this tonite and report back.

Just went to the Autoparts store and got a 5 pack of fuses. Hope I don't need them!
 
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Old 02-08-16, 03:38 PM
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Back to the drawing board

I wired it as shown and it turned on but does not turn off in auto mode and only turns off in manual mode when I adjust humidistat below current humidity.

Could it be the relay? Maybe it is broken or is on the wrong white wire. I did not move it off of the wire it was on but it is from a previous install in which the humidifier was not working..
 
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Old 02-08-16, 10:05 PM
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With no current flowing that current sensing relay should be off. It could be defective.

If you'd like to replace it and let the furnace control the humidifier directly.... purchase a 24vac relay..

They are available all over the web.
Packard Fan Relay SPDT 24 VAC: Hvac Controls: Amazon
 
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Old 02-09-16, 05:43 AM
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Thanks

I ordered a new GA50 already. If that doesn't work for whatever reason I will try the relay you linked and try to hook it to HUM and C without blowing another fuse!
 
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Old 02-09-16, 05:47 AM
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I am going to ask a dumb question.. If HUM only sends 24V when the fan is on, why the need for a relay? WHy can't we just hook up to hum and C?
 
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Old 02-09-16, 09:51 AM
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You humidifier already has a 24v transformer and a relay in it. Therefore it's considered self powered switching which means it just needs a contact closure to operate.

If you connect your 24v HUM terminal to the leads you will be sending 48vac to your humidifier relay. The relay would smoke pretty quick.

The new relay is used to isolate the furnace AC from the humidifier AC.
 
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Old 02-09-16, 10:47 AM
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Great explanation

I thought the relay would let current flow thru the board, but it is really just using that signal to close that external circuit...

If you were doing it would you use the GA50 or the relay? I noticed online a lot of posts about failed GA50s or ones that came new and did not work.
 
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Old 02-11-16, 03:09 PM
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Back to the drawing board

I got the new GA50 wired in. Was excited when I hooked it up and the humidifier stayed off until the heat call. It unfortunately turned off a few seconds later. Now each time it will come on and shut off after a few seconds.

Maybe a bad GA50 or something in the humidifier?

My meter just broke so I can't test resistance on the GA50. Excellent!
 
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Old 02-11-16, 05:58 PM
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Make sure the GA50 is installed on only ONE wire and it works best on the neutral wire. That is usually white but not always.
 
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