water not draining from vent pipe in gas furnace

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  #41  
Old 12-10-07, 06:58 PM
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THANK YOU for that post. Finally someone who has the same furnace, and you've confirmed that there is no furnace drain. This is a terribly designed furnace. Now I really may have to look at venting out the right side, since that fixed your problems. In your case, you don't need the trap on the exhaust pipe because it's horizontal and the condensation is simply rolling down the pipe and out of the house. I can't do it the same way as you because my furnace is in a basement, below grade, so I have to rise vertically before exiting the house. I'd like to go out the right side, go up and then over to the existing pipe where it exits the house so that I don't have to drill another hole in the house and fill in the old one. This adds one 90 degree elbow and a few feet of pipe to the exhaust. I don't know how many 90 degree turns are allowed. Anyone know the answer to that?
 
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  #42  
Old 12-10-07, 09:23 PM
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GMN 080-4 Venting

Right out of the install manual:

"The maximum recommended vent length is 60 total equivalent feet with each long radius 90 elbow (3 max.) counted as 5 ft. & each 45 elbow (6 max.) counted as 2.5 ft. The vent run dhould be as short as possible with a minimum length of 5 ft. for verticle run, & 3 ft. for horizontal run. When determining vent lenght DO NOT count vent terminal or drain trap assembly. (Short radius elbows are equivelent to 7.5 ft.)"

Hope this helps.
 
  #43  
Old 12-11-07, 01:22 AM
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What are those yellow caps (or whatever they are) located at the 3 o'clock and 6 o'clock positions on the fan housing? I can't tell from the small pictures but they may be drain fittings that you could attach a plastic hose and then form a trap to allow the water to drain.

Just what I see in the picture, I have never seen one of these furnaces.
 
  #44  
Old 12-11-07, 01:57 PM
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Yellow Caps

They are indeed caps. The installation manual makes no mention of them. The only thing I can figure is this venter is used on various models of furnaces. Maybe they are used as drain fittings on another furnace.
 
  #45  
Old 12-11-07, 03:53 PM
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The yellow caps fit over what seem to be venting holes in the draft inducer fan. When I first started having the water problem about a month ago, I had someone come out to look at the furnace. He found the water in the flue collector box, and he suggested that I remove the lower yellow cap and attach a tube to drain water as it collects in the draft inducer. I did that, and water trickled out occasionally, but it didn't fix the problem.

Grady - thank you for the instructions on the exhaust vent. I will have to check to see how I can fit within those guidelines when venting on the right side. There are currently four 90 degree elbows, so it's in violation of the recommendation.
 
  #46  
Old 12-11-07, 07:14 PM
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bpc--venting

One VERY common mistake made by installers is the use of short radius ells. For example 3 long radius = 15 equiv. ft. and 3 short radius = 22.5 equiv. ft. You can see from that brief example how important it is to use long radius ells, particularly if the vent system is marginal.
 
  #47  
Old 12-12-07, 01:51 PM
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When you ran a drain from the stubout at 6 o'clock, did you trap the line? Can you pull off the inducer fan assembly and see if that is a separate passgeway inside the assembly? The M in your model # means it's a multi-position furnace. It sure looks like the 6 o'clock is the drain for vertical installs and the 3 o'clock is for horizontal installs. Try installing a drain line form the 6 o'clock stubout, make a trap that's at least 2 inches high, fill the trap with water and try running the furnace.
 
  #48  
Old 12-12-07, 03:40 PM
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What dj says makes -perfect sense. That would put the drain even lower than how you rigged up your homemade drain. Not only that: Just because you put in a seperate drain, there probably still is condensate forming right in the exhaust gas, and still collects in the ventor with no escape.

I'm going to try to remember and check out that Goodman -I- was working on a couple of weeks ago to see how that was done, as that furnace has none of your problems.
 
  #49  
Old 12-12-07, 06:04 PM
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Condensate Drain

The installation manual says nothing about installing a drain from the venter. This furnace comes from the factory vented out the left side exactly as bpc's furnace is configured.

bpc: Just out of curiosity, do you see a part number stamped on the venter? It would be something like B12345-01
 
  #50  
Old 12-13-07, 08:38 AM
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My exhaust vent has long radius ells, and I will make sure to use long radius ells if I relocate the vent to the right side.

I didn't trap the line I ran out of the venter stubout, so I will try that.

The condensate forming in the exhaust gas can (and does) drain out the trap at the bottom of the exhaust pipe. It definitely does have a way to escape. It's the water collecting in the flue collector box that's causing the problem.

I will check the part number on the venter tonight.
 
  #51  
Old 12-13-07, 08:52 AM
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My curiousity got the best of me. I went to that Goodman furnace #GNP080-4, that I had worked on that is set up JUST like yours, and the bottom yellow cap was removed and it indeed had a drainline for it going into the furnace's condensate trap! This furnace also is vented left with the exhaust at top left (like yours) and the other yellow cap cover is still on in the 3 o'clock position. It also has another drain hose coming from the bottom left corner of the collector bax as you do in your photo.

So they did do what I mentioned: They are getting rid of condensate from both inside the furnace and from inside the ventor itself. I THOUGHT so.

BTW, the factory condensate trap is quite elaborate, and is this flatish long black piece of plastic with various inlets for the drain tubes.

I just went back and looked at your first pic and where you said that this was the tube you added? Well, the furnace I just looked at had a factory one actually installed right in that cover (more to the right a tad from where yours is) on the bottom left, and lower than where you put yours.

But if you put a drain hose on that 6 0'clock position(currently yellow capped) fitting, per dj, I bet your problem is solved.
 

Last edited by ecman51; 12-13-07 at 09:04 AM. Reason: Added last 2 paragraphs
  #52  
Old 12-13-07, 06:40 PM
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Regarding the part number for the venter: there's some white text stamped on the venter (you can see it in my first picture); it says "2UL 72957". The second letter may be a "D" instead of a "U"; it's hard to tell. The venter also has a sticker attached to it. It's made by Fasco Industries, and it has two numbers on it: "No. 7021-9565" and "Cust Part No. B28330015".

I removed the yellow cap and attached a drain tube to the hole in the "six o'clock" position on the venter, put a "trap" in the drain line, and filled it with water. Then I ran the furnace. I tried it two different ways: with my homemade drain on the flue collector box hooked up and with my homemade drain blocked. Unfortunately, the drain on the venter hole didn't do anything in either configuration. The water filled up in the flue collector box high enough to spill into the venter, then it entered the tube connecting to the pressure switch and the furnace shut off. It sure seems like it should drain out the "six o'clock hole", but it just won't. When I removed the drain tube after my test, some water did spill out - not a lot, but some. But when the furnace is in operation, the water will not come out.

It's very interesting that the furnace that ecman looked at has a drain tube in almost the same position as the one I put in on my furnace. That furnace is a different model. It's probably newer, and Goodman must have added the drain when they realized there were so many problems with the GMN080-4. My condensate trap isn't as elaborate as the one that ecman describes. Mine is white PVC, it's attached to the bottom of the exhaust pipe, and it has two outlets for tubes to drain water out of it (you can see it in my first picture).

I think my best bet is to move the exhaust to the right side. Grady - you said this furnace comes from the factory vented out the left side like mine. Does the manual say it's OK to vent it out the right side? There's a cutout in the sheet metal that sure looks like it's there so that you can install the exhaust on the right side, but I'd like to make sure before I do it.
 
  #53  
Old 12-13-07, 07:08 PM
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Do those nubs that stick out in the 3 and 6 position with the yellow caps require to knock out some plastic inside?, the way a garbage disposer has that same nub sticking out?. To activate it for use you must drive out the metal inside to open up the pasageway. Did you look inside after removing the yellow cover to see that it was not plasticed over inside?
 
  #54  
Old 12-15-07, 07:05 AM
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bpc/venting

Yes, you can vent out the right side according to the manual. If you will send me your e-mail address via a Private Message, I will try to scan the instructions & send them to you.

The number for the venter in my book is B28330-01 which is the same as yours except for the "5" at the end of yours. Maybe a fifth generation?
 
  #55  
Old 12-15-07, 11:03 PM
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have you considered trimming the tube going to the pressure switch? the one that keeps filling with water? elimintaing the low point would be the easiest thing i can think of.
 
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