# Furnace drain problem



## HvacWiz (Nov 24, 2006)

*Have the checked to see that the furnace is setting level or with a slight pitch to the front.*


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## yuri (Nov 29, 2008)

It needs an open 'T' on the drain line like this one and to be sloped slightly forward and level side to side. Also the discharge pipe from the furnace AND the black condensate trap MUST be on the SAME side of the furnace. If not it won't drain properly and water backfeeds into the ventor fan. There is an adaptor kit from Lennox if it cannot be setup that way. I have sold/seen 100's of those units and have had no drainage problems. Take digital pics of it with the front cover off and post them here and I may recognize the problem/with the other guys also.


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## jkennedy99 (Dec 27, 2008)

The furnance is level side-to-side. As I stand in front of the furnance, the level shows the furnance is almost exactly level, but it is just a hair angled to to the back. Is the normal set-up to be tilted slightly forward?


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## jkennedy99 (Dec 27, 2008)

Thanks Yuri, the furnace set up is an upflow position. The exhaust pipe and black condensate box are located on the same side of the furnace. The "T" you are referring to is in place (see attached pictures). There are two rubber hoses connected to the condensate box. When I pull off the condensate box (as the furnace is running) only the hose coming from the exhaust pipe has water coming out. The hose running from the large cold header (collector) box behind the inducer fan does NOT have water coming out of it. However, once the furnace hits the temperature on the thermostat and winds down, a good cup of water, or more, comes flowing out of that second rubber hose.

Let me know if you see anything on these pictures that does not look correct.
thanks,
joe


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## yuri (Nov 29, 2008)

Looks reasonably good to me. I had a York unit with a similar problem and it needed to be sloped forward slightly. Get them to jack it up and slide a metal sheet metal S clip in to give it some slope. I would also check both the hose and ports from the collector box and the ports where the trap attaches to for blockage. They had a couple where the trap attaches that were not drilled out fully. You can also try run it without the burner box cover attached for a short while. That furnace should start draining within 3-4 minutes with the trap properly full/primed (longer if you drained it). If it does then the intake may be blocked/too long etc and possibly contributing to the problem. The pressure switch should stop the unit but that is still a possibility. I had 2 G26 units with partially plugged intake pipe which will increase the velocity of the flue gas entering the ventor fan and "carryover" water into the ventor fan. One had a burger wrapper get sucked in and the other was a wasps nest.
Good Luck


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## keithv51 (Jan 25, 2010)

Was there ever a resolution to this problem? I'm having a similar problem with the same furnace originally installed in December 2007. We detected the problem almost immediately and the installer has been very good about coming out to try to fix it but after replacing pretty much the whole furnace once and many individual parts several times we still have a problem. After running for about 40-45 minutes the furnace shuts down even if the desired temperature hasn't been reached. The error code usually shows 4-3 at that time, but sometimes displays 2-5. Sometimes the 2-5 code is displayed while the furnace seems to be running normally. The condensate drain has a steady drip while the furnace is running, but I'm not sure which of the 2 black hoses the drip is coming from. When the furnace shuts down I also get a fairly large discharge of water.

The furnace starts up again after some timeout. Once the desired temperature is reached in the house, operation seems fine -- we only see the problem if we need to raise the temperature more than a few degrees (like first thing in the morning).

The drain setup seems similar to what's in the posted pictures. The furnace is sloped slightly forward. From side to side, the large pipe that at least one of the 2 black drain hoses comes from is sloped slightly away from the side of the furnace the trap is on.

The installer got a Lennox tech to come out last week and they've suggested some things to change. However, I'm not very optimistic because it seems like he only suggested doing stuff that's already been tried at least once already.


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## yuri (Nov 29, 2008)

Get your tech to read this service bulletin:
http://tech.lennoxintl.com/PDFs/0639.pdf
May have a partially plugged drain port.
Tell him to check the trap for small cracks and the port it attaches to. Can get airlocked if that happens. He should also remove and reinstall the trap and put silicone on the orings for the trap. Once again a TINY air leak can cause it to get airlocked/drain slowly.


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## keithv51 (Jan 25, 2010)

Thanks Yuri! I'm not sure the service bulletin applies. It seems to apply only to left side drain connections. I didn't mention in my original post, but ours is on the right. I'll mention it to the tech when he comes out anyway just in case.

I assume your other comments about checking for leaks would apply with either setup so I'll also discuss that with him too.


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## yuri (Nov 29, 2008)

We have installed about a thousand of them so I am quite familiar with them. Blockage can apply to either side as it is an identical port fitting. VERY rare that we have drainage problems with them but my Cdn. Lennox tech guy suggests those other checks.


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## beenthere (Oct 11, 2008)

Yuri dreams Lennox.

I think he went to school with Dave. :laughing:


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## yuri (Nov 29, 2008)

Yeah. Started with Dave in 1978. Hooked up with Willis Carrier for awhile (rocky relationship). Beenthere myself a few times. LOL:laughing:


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## beenthere (Oct 11, 2008)

yuri said:


> Yeah. Started with Dave in 1978. Hooked up with Willis Carrier for awhile (rocky relationship). Beenthere myself a few times. LOL:laughing:



LOL... So you've kept your thumb on the pulse of things.


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## yuri (Nov 29, 2008)

Yep. Mom still has one (son has spare parts). Going to pressure test one tomorrow.


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## Tator1076 (Dec 22, 2009)

I work on Lennox and the black cover behind the draft motor is on recall. The ports get plugged up time to time becasue too small. I just replace 10 of them all ready.


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## Tator1076 (Dec 22, 2009)

You make sure the pvc outtake is slopping back to the furnace? If its not it may hold water and slowly coming back to the furnace.


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## yuri (Nov 29, 2008)

The collector box is not on "recall". The port where the pressure switch tube attaches gets plugged with sulfur and causes pressure switch tripping problems on some of them. Lennox will supply a new one if less than 5 yrs old and homeowner pays for the labor to install it.


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## jkennedy99 (Dec 27, 2008)

*Lennox*

keithv51, I feel your pain, I had a bunch of parts replaced on my new furnace before a solution was found. Warranties are only worth so much if the tech can't determine the problem Anyway, below is everything done with my situation, some of which may not have been the issue:
-The main problem was the intake vent was pulling in condensation and flue gas from the exhaust. This occurred because the intake vent and exhaust vent were about 2 inches apart (which is correct) but neither vent was extended out from the side of the house. If you read the vent termination section of the manual, you will see the exhaust vent should be a minimum of 8 inches separated from the intake vent where they terminate (assuming your vents go out the side of the house vs. the roof). So I put a 12 inch extension on the exhaust pipe, and my furnace has worked fine since. Other things to consider with the exhaust termination, is it under a deck or roof extension? The exhaust gas can hang up and get sucked into the intake. If the PVC pipe is in an unfinished basement, the manual suggests you insulate the pipe. You can also put a 90 degree elbow on the intake vent if you have limit space to work with.
So, in my case, what happened was over an hour of so the condensation getting sucked into the intake caused the pressure switches to trip several times until the system shut down (error code 4-3). Do you have a two stage blower? If so, turn off the furnace, crank the heat, after 10 minutes the fan will flip to high mode and two additional burners will kick on. If you are having the issue I had, the pressure switches will flip and the fan and burners will drop right back down to the first stage (you can hear this with the cover off).
-As Yuri noted, the black condensate box was cracked on a seam. I put silicone on it, and they did eventually replace it.
-Some small PVC shreds (from when the PVC was cut) were blown out of the black rubber tubes, this did seem to increase the water drainage at bit.
-They drilled a small hole at the base of the combustion fan and put a drain hose on it. A small amount of water does come out, but those combustion fans are designed to handle some water. I doubt this helped with my problem, as it was done before I figure out the exhaust extension. 
Best of luck,
Joe


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## Tator1076 (Dec 22, 2009)

yuri said:


> The collector box is not on "recall". The port where the pressure switch tube attaches gets plugged with sulfur and causes pressure switch tripping problems on some of them. Lennox will supply a new one if less than 5 yrs old and homeowner pays for the labor to install it.


 

I think I will call Lennox later today and find out how come we get the bad Heat TXV and recall on the black box but not you all. We should get the same stuff out of Dallas Texas. It [email protected]@@ me off when I have to tell customer you just payed 6 thoundsand dollars for new systems but we need more money to repair it.


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## beenthere (Oct 11, 2008)

If a customer "just" paid you 6 grand to install the furnace. then you shouldn't be charging them. It should be covered under your 1 year labor warranty.


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## Tator1076 (Dec 22, 2009)

beenthere said:


> If a customer "just" paid you 6 grand to install the furnace. then you shouldn't be charging them. It should be covered under your 1 year labor warranty.


 
Sorry it was like furnace and a/c then when warranty is up you have to pay more. Sorry need to make it little more clear. I'm big about customer happiest.


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## Scuba_Dave (Jan 16, 2009)

I'm wondering why you would have to pay more when an ongoing problem hasn't been fixed ?
They tried that with my car, there was actually a deductible that was supposed to be paid
I told them they didn't fix the problem, so I wasn't paying them again to try to fix the same problem
They tried the same thing when the warranty ran out
I had all the paperwork shwoing the ongoing issue & that it was never fixed
....stupid problem dashlihts woudl go to bright, but a PIA for nite driving


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## gl51802 (Dec 5, 2015)

*Hi Efficiency furnace exhaust drain*

I had a similar problem on a Lennox hi eff gas furnace, 
but solved it by adding a tee in the overhead outlet exhaust line. The furnace drain may become plugged or not big enough for all the condensate flowing back. Put a tee pointing down just before the pipe drops back into furnace. at the bottom of tee, put in reducer and adapter to small drain hose. Tie the drain hose with at least a 1 ft loop seal. I divert a lot (most/ of condensate flow to keep it out of the furnace and furnace drain system.


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## Dude55 (Sep 24, 2021)

gl51802 - I am having the same issue, could you elaborate on what you did to fix the issue and maybe provide a diagram or pics? Thx.


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## supers05 (May 23, 2015)

Dude55 said:


> gl51802 - I am having the same issue, could you elaborate on what you did to fix the issue and maybe provide a diagram or pics? Thx.


This is a 13 year old thread. OP hasn't been around since 2010. Thread has been dead since 2015.

You really should start your own thread. We'll need to know your model number. Flush out the drain to start. Then explain evaluation exactly what is exactly happening.


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