water not draining from vent pipe in gas furnace

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  #1  
Old 11-24-07, 07:29 AM
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water not draining from vent pipe in gas furnace

I have a Goodman GMN080-4 90% gas hot air furnace, about 15 years old. When it comes on, it will run for a while, then shut off before reaching the thermostat temperature. I checked the diagnostic light, and itís blinking three times, indicating a pressure switch problem. I also noticed water in the tube going from the draft inducer fan to the pressure switch. I removed the tube and blew the water out of it. I also removed the draft inducer and saw about an inch of water in the black plastic collector tub behind the draft inducer. I siphoned this water out, started up the furnace and it worked fine for a while, then the same problem. I think the problem is that the condensation is not draining properly, and itís backing up into the draft inducer. I have a PVC exhaust pipe with an unusual fitting on the bottom of it. The fitting has a tee that connects into the draft inducer, and the fitting also extends about 8 inches below the tee, where itís capped. This fitting has two small outlets, just below where the T connects to the draft inducer, and each outlet has a plastic tube connecting to a condenser pump on the floor. It seems to me that I should see water draining down these tubes when the furnace is running; however, I donít see any water in the tubes. I thought the drain lines might be clogged, so I disconnected the draft inducer and poured water into the T. The water came out of the outlet tubes, proving that the drains are not clogged. I hooked everything back up, and I get the same problem Ė condensation doesnít drain, water backs up into the draft inducer, pressure switch opens, and furnace shuts off. Any ideas? Does the fitting at the bottom of the PVC exhaust pipe (by the way, is this a ďcondensate trapĒ? It doesnít look like a ďtrapĒ) need to be replaced?
 
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  #2  
Old 11-24-07, 10:11 AM
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Hi b:

When the furnace is running, see if air is being drawn thru the drain opening. It won't drain if it isn't trapped.
 
  #3  
Old 11-24-07, 02:01 PM
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water in furnace

Thanks for responding. I've done some more testing, and I think the problem is a little different from what I described before. The water is collecting in the flue collector box, which is mounted to the furnace directly behind the draft inducer. I thought the water was condensation backing up into the flue collector box from the PVC exhause pipe, but this is not the source of the water after all. I ran the furnace briefly without the PVC pipe connected, and water still collected in the flue collector box. This tells me that the water is being generated by the furnace itself, not by condensation in the exhaust pipe. I can't imagine how the furnace could be generating so much water, but that appears to be what is happening. When the flue collector box fills up too high, it overflows into the draft inducer and gets into the tube to the pressure switch, tripping the pressure switch and turning the furnace off. I've been reading about furnaces, and I notice that many furnaces have drains for the purpose of draining water, but mine does not have such a drain. Is there a way that I could drill a hole in the flue collector box and mount a drain tube so that I could drain the water out as it collects? (The flue collector box is made of black plastic, probably ABS plastic.)
 
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Old 11-24-07, 03:01 PM
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Don't go altering your furnace!

Water condenses IN furnaces, not in the drain, due to secondary heat exchanger (the bottom heat exchanger)and the temperature drop coming down to the dew point. They are supposed to do that. That is why high efficiency furnaces are also called condensing furnaces.

I percieve that actually as a good sign the furnace is flowing properly, actually. You sure water is not able to get out some way you are not aware of that box?, say even via the inside of the back of the center of the draft inducer where then it runs along the bottom of the inducer into your pvc trap? Maybe you simply have gunk built up behind the inducer where it is creating a wall it has to get over. ??

And how do you even know that collecting water is your problem? Maybe you opened up and discovered that, but in reality, when you have it all together and running, the water that is in excess of what you have discovered, is simply being backed up even MORE by a clogged pvc trap? Blow that thing out every which way. Then add some water after if you want to get the trap back to it's trap function.
 

Last edited by ecman51; 11-24-07 at 03:08 PM. Reason: Added last paragraph
  #5  
Old 11-24-07, 05:18 PM
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water in furnace

Thanks for your response. I am reluctant to alter the furnace; that's why I posted here first. I can't see any way that water can get out of the furnace. I've looked everywhere, and there is no drain. The only possible way is for the water to spill into the draft inducer, which would spin it 270 degrees counterclockwise and uphill to get to the PVC exhaust pipe (which connects to the draft inducer at the top). Maybe that's how the water is supposed to exit the furnace, since there is no drain. (Maybe the draft inducer is old, and isn't spinning fast enough to expel the water??)

I really don't know if the water that's collecting in the flue collector box is a problem, but it does seem to be affecting the pressure switch and shutting down the furnace (but again, maybe it's because the draft inducer doesn't spin fast enough to expel the water). As far as the PVC exhaust pipe is concerned, I don't think it's clogged. I've blown out each of the two outlets, and I've poured water into the tee where it connects to the draft inducer and the water comes out the outlets on the exhaust pipe, so it doesn't seem to be clogged.

My initial thought was that water had collected in the furnace from the air conditioner over the summer, and now it was draining into the flue collector box when the furnace runs. My second thought was a clogged PVC exhaust pipe. My third thought was that so much water shouldn't be collecting in the flue collector box. Now my latest thought is that the draft inducer is supposed to expel the water, and it is worn out and needs to be replaced. Any thoughts? This is really getting frustrating.
 
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Old 11-24-07, 06:04 PM
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Drain

There has to be a drain somewhere. I just don't remember where on that furnace nor can I find my Goodman manuals at the moment.
 
  #7  
Old 11-25-07, 07:16 AM
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water in furnace

I don't think there's a drain on this furnace. Unfortunately, I don't have the manual, because the previous owner of the house didn't leave it for me. And Goodman apparently doesn't post manuals on their website. I would love to know what the manual says about water in the furnace, but my guess right now is that the draft inducer is supposed to expel the water (if that's the case, I think it's a dumb design; it would be much better to have a drain).
 
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Old 11-25-07, 11:30 AM
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SUCK that water out with say a shop vac, or syphon, and then hook everything back up and see if now the pressure switch system works. If it still does not, then you know it is something else and not that standing water.
 
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Old 11-25-07, 11:35 AM
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water in furnace

Oh, I've done that 100 times. Every time I suck the water out of the flue collector box and then hook everything back up, the pressure switch works just fine, until the flue collector box collects with water again, overflows into the draft inducer, and gets into the tube that goes to the pressure switch. Then the furnace shuts down again. So I don't think it's actually the standing water in the flue collector box that's the problem. The problem occurs when the water spills into the draft inducer and then gets into the pressure switch tube. That's why I'm tempted to drill a hole in the flue collector box and attach a tube so that the water will drain out as it is generated.
 
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Old 11-25-07, 12:29 PM
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"I removed the tube and blew the water out of it. I also removed the draft inducer and saw about an inch of water in the black plastic collector tub behind the draft inducer. I siphoned this water out, started up the furnace and it worked fine for a while, then the same problem. I think the problem is that the condensation is not draining properly, and itís backing up into the draft inducer. I have a PVC exhaust pipe with an unusual fitting on the bottom of it. The fitting has a tee that connects into the draft inducer, and the fitting also extends about 8 inches below the tee, where itís capped. This fitting has two small outlets, just below where the T connects to the draft inducer, and each outlet has a plastic tube connecting to a condenser pump on the floor. "


The black plastic tub you refer to- I think that's the water collection point and internally it is blocked. It sounds like water should flow from there to the point where the T connects to the inducer assembly. Can the whole assembly be taken apart? Is this your first Winter in this house?
 
  #11  
Old 11-26-07, 05:43 PM
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water in furnace

The "black plastic tub" is actually the flue collector box. I didn't know what it was called when I first posted. It's mounted to the furnace just behind the draft inducer. There's a large circular hole in the middle of it where the draft inducer fan sucks the flue gases out of it and sends the gas into the exhaust pipe (PVC). The water is collecting in the bottom of the flue collector box, and it's filling up to the level of the large hole in the middle, then the water spills into the draft inducer fan. The tee in the exhaust pipe that I referred to is about 7 or 8 inches above the water level, so the water can't drain into it. It does seem that there should be a drain somewhere so the water can get out of the flue collector box, but I swear there is no drain on this furnace, at least none that is hooked up (and I can't see anywhere to hook one up). The only drain is on the PVC exhaust pipe (to drain condensation from the exhaust gases), with a tube that goes to a condensate pump on the floor. There is no other water drain line going into the condensate pump. The furnace is about 13 years old, and I've been in the house for five years and I've never noticed this problem before this year. It's hard for me to believe that it has been operating for 13 years with a drain that was never hooked up, and I can't see where to hook one up, so I really don't think there is a drain on this furnace. I wish I had a manual, but the previous owner didn't leave one. I called Goodman today, and they don't even have a manual (nor would they provide any advice or technical information because I'm not a licensed installer). As far as taking everything apart: I've taken off the draft inducer, which attaches to a piece of sheet metal. I could remove the sheet metal and then the flue collector box, but I'm reluctant to do that because I'm afraid I might ruin the gasket between the flue collector box and the furnace. I really think drilling a hole in the flue collector box and running a tube from there to the condensate pump on the floor would fix my problem, but I'm reluctant to do that too. By the way, I'm calling this a "90% furnace" because the specs say "heating input 80,000 BTU, output 72,400 BTU". It doesn't say "90% furnace" anywhere. Many thanks to all of you who have responded, and I'm interested to hear any more ideas. Question: does the heat exchanger have fluid in it? If so, could it be leaking into the flue collector box?
 
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Old 11-26-07, 06:29 PM
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Maybe the drain line you think it should have and "doesn't", IS really there, hiding in the lower blower compartment, and was drilled through into that compartment, where from there, it joins into your trap area of the exhaust.

Two heat exchangers: Both hollow.
 
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Old 11-26-07, 07:59 PM
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Drain

Some furnaces do have drain connections in the blower compartment. This may be one. Darn I wish I could find my Goodman book.
 
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Old 11-27-07, 07:13 AM
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Originally Posted by Grady View Post
Some furnaces do have drain connections in the blower compartment. This may be one. Darn I wish I could find my Goodman book.
Exactly. That is what I was thinking. I have seen it. Some furnaces have this web of drain tubes, above and below,

WE have Goodman's in some of our rentals, but not sure if this is the one with the drain tubes down in the blower compartment, but would not doubt it based on poster's lack of findings.

I can try to rack my brain and if I can remember which unit's, may run there to satisfy my curiousity.
 
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Old 11-27-07, 06:58 PM
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Thumbs up Found it

Found the Goodman book, finally.
After some reading, here's what I've learned:
1: The trap is the drop leg directly outside the furnace on the vent system.

2: The trap MUST NOT be uphill from the venter discharge. The horizontal part must be flat or very slightly downhill.

3: Both drain lines off the trap should be go to a drain. The higher one is an overflow.

4: The trap should be primed at the begining of the heating season.

Not in the book but worth doing: Remove the trap assembly & wash out with a garden hose, re-install, prime with water, & try it. Let us know the results.
 
  #16  
Old 11-28-07, 06:05 AM
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It hasn't worked all these years because it's piped wrong or needs an additional hole in the flue collector box. Something is being overlooked.
 
  #17  
Old 11-28-07, 04:44 PM
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water in furnace

Sorry I didn't post yesterday. I spent the day crawling around in my furnace looking for a drain . Grady's response is interesting. Is that from the GMN080-4 manual? That pretty much does describe the vent exhaust on my furnace. However, that describes the exhaust only, and the two "drain lines" it refers to are for draining condensation that forms in the exhaust pipe, not for draining the furnace itself. Does the manual say anything about a drain on the furnace?

The part that says the trap must not be uphill from the venter discharge is especially interesting. I assume the "venter discharge" is the outlet from the draft inducer fan. The furnace is designed so that this outlet can point to the right or the left out of the furnace. The fan spins counterclockwise, so if you point it to the left, the "venter discharge" is at the top of the draft inducer. If you point it to the right, the "venter discharge" is at the bottom of the draft inducer. In either case, the venter discharge connects to a tee with the trap attached to the bottom of the tee, so it's always below the venter discharge. But humor me for a minute and assume that I'm right that this is a badly designed furnace with no drain. In that case, installing the draft inducer to vent to the right (so that the discharge is at the bottom of the draft inducer) would work MUCH better, because as the water spills into the draft inducer, the fan would only have to push it horizontally a few inches into the vent. Mine is set up to discharge to the left, in which case any water that spills into the draft inducer has to be spun counterclockwise 270 degrees uphill to reach the discharge. I don't think the fan is strong enough to do that, and that's why water is remaining in the draft inducer and getting into the pressure switch tube (and also dripping from the joint between the draft inducer and the tee). I guess I could try relocating the exhaust pipe to the right of the furnace, but then I'd have to add a turn to the exhaust pipe, and I'm not sure what's acceptable in that regard. (By the way, it would be much easier to see what I'm talking about with the left and right discharge options if I could show you a picture.)

I also agree with daddyjohn that I need a hole in the flue collector box to drain the water, but I'm not sure how to make one that's watertight and safe.
 
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Old 11-28-07, 06:20 PM
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bpc,

Reread dj's response. You are interpreting what he said wrong.
 
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Old 11-28-07, 06:45 PM
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water in furnace

Maybe. I'm interpreting dj's post to say that there are two possibilities: (1) the furnace is piped wrong, or (2) it needs an additional hole in the flue collector box. If there is a drain that's not connected, then #1 is right. But I've looked everywhere on this furnace 100 times, and there is no drain, so I'm discounting #1 and moving on to #2.

I'd love to hear from somebody who has a manual for this furnace (GMN080-4) that shows how to connect a drain. It sounds like Grady has a Goodman manual (though I'm not sure if it covers this particular furnace), but the part he quoted dealt with the exhaust pipe, not a furnace drain.
 
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Old 11-28-07, 07:21 PM
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Gmn 080-4

I do have a Goodman manual & I was looking at the part for the GMN series of furnaces. Yes you are right, it is a poorly designed furnace many of which have been replaced due to cracked heat exchangers.
The only drain they talk about is via the venter. I agree with the statement about venting out the right rather than the left side.
One thing they mention & seem to be insistant upon is the proper placement of an 'O' ring & a restrictor plate. These are located behind the panel on which the venter is mounted. I worked on a different brand of furnace once where the restrictor plate (ceramic) was cracked & set this furnace in a fit. Maybe something like that with yours?

Have you tried cleaning the trap or at least made sure it was filled with water?
 
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Old 11-28-07, 07:25 PM
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He is saying that your furnace would not have worked all these years if it had needed another hole in it to drain the water. It is the way he wrote it that comes across perhaps as some double negative. But if you read it again, keeping in mind my interpretation ,then it should be clear.
 
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Old 11-28-07, 07:39 PM
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Grady. I am glad you brought up the restrictor plate!

I found this round hard ring in a furnace I worked on recently and was not sure where it came from and upon whom it fell out on. But when I had the ventor assembly out, I tried fitting it in the 2 or so inch hole and it fit perfectly. But it would just fall out again as it is like just sitting in there edge to edge with the housing of the furnace itself. It doesn't seem to snap into anything.

I analyzed the rear of the ventor itself and saw no way how the ventor could hold it in, as it looked like the rim of the rear of the ventor would only compress (seat) into a female depression area outside that filler o-ring restrictor plate piece you are refering to.

After running the furnace it runs fine. But I don't want to be responsible for some furnace with some designed part left out! Maybe the furnace MAY start acting up as the weather gets colder and the furnace runs longer?

You'd think by leaving out the restrictor plate (like I inadvertently did) that this would have immediately affected the pressure in the furnace and cause the pressure switch to cut off. But it hasn't so far. But maybe the plate acts more like a designed dam for condensate water?

......

Now another thought occured to me: Maybe these restrictor plates CAN fall out and maybe that is what is causing the poster's problem. Maybe it is laying in the ventor tunnel at the rear, causing problems.

Maybe I should call up one of the 8 or so listed suppliers of Goodman products in my area (was given printout a week ago by local shop) to see what they have to say as maybe these thigng are just epoxied in at the factory and can unglue? and maybe can do more harm that way than if left out. As long as there is not a problem if left out...... - well, I simply need an answer from someone about this.
 

Last edited by ecman51; 11-28-07 at 07:56 PM. Reason: Added last two paragraphs
  #23  
Old 11-29-07, 09:43 AM
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water in furnace

Many thanks to you guys for sticking with this thread.
Regarding the venter trap: I made sure this is full of water. I filled it myself by disconnecting the venter and pouring water into the tee until it overflowed through the drain tubes in the trap. The problem can't be in the trap anyway; the water is never getting that far. It's overflowing into the venter and then into the tube to the pressure switch. If the venter were stronger, it would propel the water into the tee and then into the trap (and undoubtedly that is happening with some of the water, but other water is getting into the pressure switch and some is just leaking out of the joint between the venter and the tee).

Grady mentions an O ring and a restrictor plate. There is a disk about 1/8" thick, and it goes on the flue collector box where the venter attaches. I thought it was plastic, but this must be the ceramic plate they talk about in the manual. Just as ecman describes, it's not attached to anything, and it falls out every time I remove the venter. I just place it back in and then attach the venter. So it's not missing or cracked, but I can't see how it performs much of a function. I don't see an O ring, though. That would be rubber, right? Maybe it's permanently attached to the venter or the flue collector box. I will check tonight.

By the way, it isn't like the furnace isn't working at all (which is good because it's 25 degrees at night now). It runs for a while, then shuts off, then runs some more, then shuts off, .... It eventually gets up to the temperature on the thermostat. (It wasn't doing that when I first posted. It was just shutting off. But now it eventually gets up to temp.) But there's always water collecting in the flue collector box, and it's always dripping out of the joint between the venter and the tee. I now suspect this HAS been happening for years, and I never really noticed it before because the furnace would eventually heat the house. I do remember finding water on the floor occasionally in previous years and not knowing where it came from.

I may try relocating the exhaust pipe to the right side of the furnace. However, I would have to add a 90 degree bend and about 3 feet of pipe in the route of the exhaust pipe. Would this be acceptable?

I still think I could eliminate the problem entirely by adding a little drain tube to the flue collector box. Anyone have any suggestions on how to do that, or any strong objections to doing it?
Again, thanks so much for trying to help!
 
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Old 11-29-07, 03:37 PM
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Originally Posted by bpc123 View Post
Grady mentions an O ring and a restrictor plate. There is a disk about 1/8" thick, and it goes on the flue collector box where the venter attaches. I thought it was plastic, but this must be the ceramic plate they talk about in the manual. Just as ecman describes, it's not attached to anything, and it falls out every time I remove the venter. I just place it back in and then attach the venter. So it's not missing or cracked, but I can't see how it performs much of a function. I don't see an O ring, though. That would be rubber, right? Maybe it's permanently attached to the venter or the flue collector box. I will check tonight.
I also called the ceramic? disc an o-ring in simply trying to describe that ring as a disc with a hole in the middle. There is no additional rubber o-ring to my knowledge. The 1/8 inch thick ceramic disc sits in there as you describe, and I, frankly, do not know what is holding it in, as the outside diameter of the disc is smaller than the round opening of the ventor itself. I can't see what keeps that thing standling vertical on edge, without falling inward toward the ventor?

After I made my post, I got thinking that one fucntion of the restrictor was a possible engineering change? to slow down some of the flue gases so that more heat could be captured by the heat exchanger. By leaving out that (loose)disc, like I did, - other than my latest theory, I'm not sure what that would hurt.

If I were you though, I'd be reluctant on making an additional hole in the collection box. These furnaces were designed, and do work, even in cold climates, which naturally causes furnaces to run and run and condense, without incident. If yours is trapping all that water, you must have some issue you need to overcome.

There must be some reason why they want SOME of that water to remain in there. (Just don't ask me what that could be). It is just like in window a/c's; people want to drill holes in bottom to let the water out, not knowing that the a/c unit was designed to trap some water in the bottom to help cool the condensor coils.!!
 
  #25  
Old 11-29-07, 05:41 PM
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O-Ring/Restrictor Plate

According to my book, the O-ring is 2ľ x 5/32 (Goodman part # B28326-06) & the restrictor plate is 1.500 (inches?) (Goodman part # B28649-05). This plate fits the 080-120 sizes. The 060 uses a 1.25 (in.?) plate (# B28649-03). The flue collector box goes on then the O-ring, then the restrictor plate, followed by the heat shield & venter.
I've used small dabs of high temp silicone to hold the O-ring & restrictor plate in place while finishing assembly.
 
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Old 11-29-07, 05:54 PM
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Ah. I get it now. That o-ring you speak of, Grady, is not really associated with the restictor disc. The rubber o-ring is inside, what I referred to as a female depression around the approx. 2 inch hole in the facing of the collector box where the ventor assembly slips into. Then when you srew on the ventor assembly (3 screws), it pushes against that o-ring.

So you think high-temp silicone will keep that ceramic disc in there,wtihout vent air pressure pushing against the back side of it, along with the moisture in there?

If you were me, would you go back there to that house and try to re-install that disc, even though there is not apparent problem? And do you know exactly what the function of that reducer disc is?: IS it perhaps to slow down the exhaust gases so the furnace recovers more useable heat? Or does it also serve a way we have not yet figured out the importance of damming up the condensate water, higher?

(Just came back from checking that furnace across the street again.)

Thought of something: How long do you need to wait after high temp siliconing in that disc, before putting the ventor back on, or I should probably really say, how long before you can turn on the furnace? It's cold here, like in the 5-15F degree range at night and 15-25F for the highs, plus some awful windchills.
 

Last edited by ecman51; 11-29-07 at 06:13 PM. Reason: Added last 2 paragraphs
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Old 11-29-07, 06:13 PM
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ecman

The O-ring goes in the depression, then the disc, next the heat sheild, & finally the venter. Since the (hole?) in the disc is larger for the 080-120 than for the 060, I have to presume the disc is to reduce the velocity of the air being pulled thru the heat exchanger. Too much air would tend to cause the flames to pull away from the burners & cause the venter to get hotter. I know high temp silicone will hold the disc. You can run a very thin bead all around the edge to hold it.

Yes, I would go back & reinstall the disc. The manufacturer put it in for a reason. Some discs are metal instead of ceramic & not flat. If the one you are working on is this way, it makes a difference which way that disc goes in but I don't remember if it is concave out or convex side out.
 
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Old 11-29-07, 06:16 PM
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I think mine was as flat as a pancake and blackish fiber like hard (ceramic?)
 
  #29  
Old 11-29-07, 07:42 PM
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Mine is also flat. I may get some high temp silicone and use that to hold it in too.
 
  #30  
Old 12-03-07, 05:03 PM
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Furnace now has a drain

It's been really cold, and I got tired of constantly siphoning water out of the flue collector box so that the furnace would run. So I decided to add the drain that should have been there all along. I drilled a hole in the corner of the flue collector box and ran a tube down to the condensate pump on the floor. Now it drains the water as it collects in the flue collector box, and the furnace runs without shutting off. I drilled the hole about 1/2 inch up from the bottom, so some water will remain in the box. I had to bend the tube so that it has a "trap" that is full of water. Not sure why that works, but it wouldn't drain without it.

Thanks to all of you for your help.
 
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Old 12-03-07, 06:13 PM
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Bpc

I understand your frustration & you gotta do what you gotta do.

If at all possible, I suggest you flip that venter around & vent out the right side & patch the drain hole with epoxy (JB Weld or similar). I think getting the venter outlet on the bottom will cure the problem.
 
  #32  
Old 12-03-07, 06:36 PM
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I think Grady has hit upon the solution which is actually an installation issue. The reason the restrictor plate is there is because they use the same ventor assembly for all size furnaces which means the fan cfm would be the same for all sizes of furnaces. Since different furnace sizes need different amounts of combustion airflow, the restrictor plates are used to "adjust" the airflow. It's cheaper to use one size fan and various restrictor plates than to use a different size fan on each model. ICP furnaces are built the same way.
 
  #33  
Old 12-04-07, 08:02 PM
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I'm considering venting out the right side of the furnace, but it's somewhat complicated. Both the gas line and the conduit for the power line are on the right side of the furnace, and they're in the way of the route that the exhaust pipe would take. I'd also have to add one more 90 degree turn in the pipe, and I don't know if that's OK or not. There are three 90 degree turns now - one inside to turn from vertical to horizontal, and two more outside the house (the last one turns down and exhausts towards the ground).

I'm running into a problem with the drain that I installed on the flue collector box. It doesn't always drain the water. When it does drain the water, the furnace works great, but when it doesn't, I get the same pressure switch problem. If I shut the furnace off and pull the tube off the flue collector box, the water pours out, so I know it's not clogged. Likewise, if I take the other end of the tube (which is normally in the condensate pump) and suck on it, all the water comes out. But during normal operation, it doesn't always drain. I routed the tubing in the shape of a trap, and there's water in the "trap" part of the tubing, and from there it goes into the condensate pump. Any ideas on why it doesn't always drain?
 
  #34  
Old 12-05-07, 11:17 AM
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What is the hieght of the trap you made? Maybe it need to be taller? At some point, you're going to have to redo the install like maybe next Spring or Summer.
 
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Old 12-05-07, 05:14 PM
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Drain trap

If you could post some pictures of the furnace including the trap, maybe one of us could see something which would jump out at us. You can post them for free at www.photobucket.com and provide a link here.
 
  #36  
Old 12-05-07, 07:01 PM
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Great idea. I will take some pictures over the weekend and post them.
 
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Old 12-09-07, 07:24 PM
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Here are two pictures. The first one (http://i249.photobucket.com/albums/g...3/DSC02141.jpg) shows the draft inducer and the connection to the exhaust pipe. You can see the condensate trap below the exhaust pipe. The drain tube that I added is in the lower left hand corner of the flue collector box, which is the black plastic box behind the sheet metal that is just behind the draft inducer. (You can only see the left edge of the flue collector box because the rest is hidden by the sheet metal.) The second picture (http://i249.photobucket.com/albums/g...3/DSC02143.jpg) shows the "trap" I formed in the drain tube that I put in. I've tried several different shapes for this trap, but it doesn't seem to matter what it looks like.

Here's what's been happening: furnace comes on, house starts to heat up, then furnace shuts off. I check tube to pressure switch, and it has water in it. I clear that water out, then I pull the drain tube (that I put in) out, and water flows out of the flue collector box. It usually won't drain by itself; I have to pull the tube out, then it drains. Other times, it does drain by itself, but water still always gets in the pressure switch tube and trips the pressure switch so the furnace shuts off. It seems to me that the flue collector box needs a place for air to come in and replace the water that needs to drain out. Drilling an air hole in the top would probably work, but I can't do that because the flue collector box is collecting flue gases, which would escape out the hole.

I'm seriously considering buying a new furnace.
 
  #38  
Old 12-09-07, 08:55 PM
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Look inside the blower compartment to see if there is a connection for the flue box drain down there.
 
  #39  
Old 12-10-07, 12:53 PM
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I've checked everywhere. There isn't one. Grady also confirmed from the manual that the only drain they talk about is the drain for the exhaust. No other drain is mentioned in the manual.
 
  #40  
Old 12-10-07, 05:35 PM
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Goodman 80-4

I have a GMN 80-4 that was installed new in my home in 1994. Vent pipe and drain installed on left side of furnace with vent rising verticaly 8' and exiting under the eve of my roof Looks just like the pictures of your system. From day 1, I have had the same water issues as you. I first elevated my pressure switch above the vent motor about 12 inches. This worked better but eventually the tube would fill with water. I added an additional drain line to the bottom of the drain trap, no help. Next I rotated the vent motor 180 degrees and remounted the motor. I then plummed the vent through the right side of the furnace (2" sched. 40 PVC), through the wall and crawl space and exited the vent just above the foundation. In other words no vertical climb for the vent. With this install I did not install the PVC trap or plastic drain lines. I have had no water problems since. I had the installer out and two seperate HVAC Techs look at the problem before I re-routed the vent they had no solutions. What I did may not be correct per the install manual but it worked.
 
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