General 1040 Dry

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Old 01-07-09, 09:23 AM
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General 1040 Dry

With winter here in Kansas, it seemed that our house was too dry and I checked the General 1040 humidifier on our furnace and found it to be dry. Previously, the saddle valve had been plugged, but it checked out OK this time. Moving on from there, I took the screen out of the water solenoid and cleaned it, also making sure that the small hole in the solenoid was not plugged.

Still no water, so next I checked the solenoid itself for operation. Using the manual ON/OFF switch on the front of the furnace, I cycled the furnace on and off several times. Sometimes, I could hear a click from the solenoid and other times not. I took my VOM and checked the voltage getting to the solenoid and, when the ON/OFF switch is closed, 25-26V reads to the solenoid for about 1/2 second and then drops to .3V. During the first 1/2 second, water starts to come out of the solenoid, and then stops, of course.

Tracing the wiring from the solenoid, one leg goes to the GA-50 current sensing relay and the other goes to the furnace control. So, I replaced the GA-50, and no change. The old one was good. There is also a pair of wires that go up, presumably to the thermostat. A couple of years ago, I changed out the manual thermostat for a new electronic LUX 1500 model.

What do I check now? The furnace is an Inter-City Model #U3642B191, furnace control General 90, Model #50A50-110.

Could the solenoid in fact be bad? However, it opens when it briefly gets the full 24V current. Could the new thermostat have something to do with it?

Chuck
 
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Old 01-07-09, 03:41 PM
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Where on the furnace is the humidifier wire tied to? R and C? HUM and C?
 
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Old 01-08-09, 11:35 AM
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Hi Jay,

The dual wire that comes from the solenoid goes to terminals C and M on the furnace controller, with the GA-50 into the wire going to C. It worked for several years with these connections, but maybe some other connection would be better. It would seem that all I need is a good voltage signal to run through the GA-50 to keep the solenoid open.

The furnace otherwise works fine.

Chuck
 
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Old 01-08-09, 11:58 AM
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I am unable to find that model # of your furnace..

How old is it?


Is "M" 24 volts?

If you can scan or take a photo of your wire diagram of your furnace.
 
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Old 01-08-09, 04:58 PM
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Jay,

I went to have another look at the furnace and realize that I gave you two pieces of incorrect data. The Inter-City furnace model number is GUI100AO16AIN. I had given you the coil number. The furnace is a 1993 model.

Secondly, the dual wire coming from the solenoid is attached to C and W on the controller. I was seeing the W as an M. The furnace controller is a General 90, Model #50A50-110. I did get that part right. It has terminals C,G,R,W, and Y.

I have scanned two sheets that came with my furnace documentation, both of which show wiring going to the furnace controller. However, I do not know how to attach them to this reply. One of the sheets shows R,Y,G,W and C all going to the thermostat, which are all shown as 24V. It is interesting also that the diagram shows the Gas Valve, Pressure Switch, HLI (Return from High Limit), and HLO (To High Limit) all going to terminal W.

I hope that this correct information causes a lightbulb of understanding to go off in your experienced brain.

Chuck
 
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Old 01-08-09, 08:40 PM
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You can send the file to my e-mail

jaymarking at gmail dot com
 
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