Wiring GeneralAire 900A to RUUD UGEB Furnace

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Old 11-03-10, 08:20 PM
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Question Wiring GeneralAire 900A to RUUD UGEB Furnace

I was hoping you could help me out with this.
I've got a:
RUUD UGEB-10EE-GS furnace
GeneralAire 900A humidifier
GeneralAire E2 Humidstat
and a Honeywell RTH230B Thermostat (already wired up previously)
My furnace had a RobertShaw HS780 that has been replaced at some point by a Honeywell S890G Hot Surface Ignition. I don't know what this thing does, but the name is clearly different from whats on the schematic, and the part looks much newer.

I've got everything installed except the wiring, and I'm worried that I might potentially drawn too much power from the furnace circuit board or screw something else up. My furnace is from 1990, so I don't think it has a HUM tap on the board, but it does have 5 taps that run to the thermostat and air conditioner. The 5 terminals I have are Y, G, W, C, R. With a multimeter I determined that I have 26 VAC on the R terminal at all times, and 26 VAC on the W when the burners are on, and 26 VAC on G if I set my fan switch to "ON" rather than auto.

My current plan is to run a wire from R (26 VAC on all the time) to the AC L terminal of the humidstat, a wire from C to the AC N terminal of the h-stat, a jumper from HUM1 to AC N on the h-stat, a wire from HUM2 on the h-stat to the solenoid, then a wire from the solenoid to W (on when burners are on) on the furnace.

The transformer in the furnace is 24 V and 40VA, also honeywell of some sort.

Does this seem like appropriate wiring?
 
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Old 11-04-10, 07:15 AM
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This furnace was under a major recall of the heat exchanger, and HSI and controls. So that's why the HSI control don't match of what you are seeing.

Have you had someone in to check this furnace over make sure all is good still?

Are you planning on using a transformer along with the furnace or no?
 
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Old 11-04-10, 10:05 AM
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I have not had the furnace checked out, but it has worked fine for the 2.5 years we've lived here.

I have a transformer that came with the humidifier, but I wasn't planning on using it, since I found 24VAC terminals on the furnace. Also, I couldn't find any place that provided 120 VAC only when the furnace was on. Only a few places that are live all the time, so I would need some other sort of switch or relay to keep the humidifier from running when the furnace isn't.

This house used to have a ER100A 1001 Energy Recovery Ventilator installed in it, and presumably a humidifier. I say this because there is a humidistat mounted on the wall, and I found the Ventilator under the stairs. Unfortunately, the wiring for both of them comes down into the basement and then goes off into the finished part of our basement. I assume it just dead ends since there are no access panels on that side of the basement to get at anything the wires might be connected to. My assumption is that someone removed both of these devices when they finished the basement, but didn't take out the wiring.

Also, here is a picture of the wiring diagram for my furnace, if it matters:
 

Last edited by Entropy42; 11-04-10 at 11:16 AM.
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Old 11-04-10, 03:01 PM
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Also, I tried to google for information about any recall for my furnace, but couldn't find anything. We are the 4th owners of this home, so its possible that one of the previous owners took care of it, but I would like to know more about the recall if possible.
 
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Old 11-04-10, 06:53 PM
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The recall was back in the early 90's when I was in the field.

We had to go out to every home that we had this furnace put in, and replace the heat exchanger, control board, and HSI. It was not a fun job for a kid who just got out of college for this! But it was keeping me busy in the spring when things were kinda quiet... so you won't see this recall on line now since it was back then.

It may of been taken cared of since you got another HSI control.

Anyway.

You can piggy back the humdiistat on to the furnace board since it does have a "larger" transformer"

This how I would wire it.

Hum---Fur
AC L----R
AC N----C (Piggy back one of the wire from the Humidifier to AC N)
HUM----W
HUM----to the other wire from Humidifiier.
 
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Old 11-04-10, 06:57 PM
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Originally Posted by Entropy42 View Post
I have not had the furnace checked out, but it has worked fine for the 2.5 years we've lived here.
May not hurt to have it checked out, or make sure you do have a CO detector in your home.

.
This house used to have a ER100A 1001 Energy Recovery Ventilator installed in it, and presumably a humidifier. I say this because there is a humidistat mounted on the wall,
HRV do use a humidistat to control it, it removed the humidity in the home in the winter when it was too much humidity, and lot of them had a timer to cycle on and off to bring in fresh air into the home.

So it's just hanging there doing nothing now?
 
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Old 11-05-10, 05:40 PM
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I wired this up last night, but never turned the humidifier on, then noticed this morning the house was kinda cold. Something has apparently gone wrong and now my furnace doesn't ignite. The blower comes on, then later the fan comes on and circulates cold air throughout the house, but the furnace never generates any heat. I rechecked the terminal voltages and they are all the same as they were (26 V on R and 26 V on W when the thermostat says to heat). Anything else I can check to try and track this down?
 
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Old 11-05-10, 07:07 PM
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And now it started working again. I disconnected the humidifier wires as soon as I got home, went around checking terminal voltages and continuity and turning my furnace on and off a few times. I'd pretty much given up and was checking the voltages of my negative pressure controls and then I noticed the burners were lit and it was working. Not gonna complain for now, but also not planning to reconnect that humidifier anytime soon...
 
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Old 11-05-10, 08:46 PM
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Maybe the transformer has become weak over the years.. may have to add another transformer or update the one on the furnace.
 
 

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