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 Repairing and Servicing Lennox Products
 Repairing / Servicing Lennox Gas Furnaces
 Condensation Blockage
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topher99

3 Posts

Posted - 12/29/2008 :  3:42:56 PM  Show Profile  Reply with Quote
It seems that my furnace is having some type of condensation blockage. The code is blink 2 + 3. I drained the black trap box on the side. I also tried cleared the small rubber tubes. I am looking for any other suggestion.

Cozy.Support

5821 Posts

Posted - 12/29/2008 :  4:26:32 PM  Show Profile  Reply with Quote
Model number?



Cozy.Support does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.

Once you know what part you need, you can contact the Cozy parts department by using the link below
http://www.cozyparts.com/Lennox-Parts/locator_form.aspx
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topher99

3 Posts

Posted - 12/30/2008 :  11:12:14 AM  Show Profile  Reply with Quote
G61MPV-36B071-08 is the series. This morning I checked the vent and intake PVC and they are to be clear and not sagging. I also emptied the black trap again and got about a cup or two of water as well. It has taken a good 24 hours between me me draining anything and it shutting off. After I drained the Black trap I did have some gurgling from the trap area. I also made sure the trap from the A/C was filled with water.
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jkennedy99

3 Posts

Posted - 12/30/2008 :  6:18:33 PM  Show Profile  Reply with Quote
I also have a G61MPV and have the same issue. The error code I get is 2 + 5, which is similar to your's, the furnance thinks the exhaust or inlet is blocked. I believe this is water from the cold header box (sits directly behind the inducer fan) not draining while the furnace runs, and therefore water gets into the inducer fan. At least with my situation, a bunch of water (maybe 6 oz-8 oz) runs out of the drain pipe, AFTER the furnace shuts down. Seems like a suction or vacuum problem, but the two companies I've had out here have not been able to figure it out.

Let me know if a bunch of water drains out when your furnace shuts show, and I can update you if I find a solution.
jk

jk
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slctech

2086 Posts

Posted - 12/30/2008 :  8:31:56 PM  Show Profile  Reply with Quote
My first question for both of you is concerning proper placement of the black drain trapped located on the exterior of the furnace. Being multi-positional furnace, they can be installed either horizontally of vertically. if installed vertically, the drain trap must be installed on the same side that the furnace vent and combustion pipes connect to. If not you will have erratic operation.
If the furnace is installed horizontally, double check the install manual closely for the proper drain location. It is crucial that it is installed in the right location.
To many times I come across your situations and it is simply due to a improperly placed drain trap.

It is very normal for excess water to drain out of system after a heat call. must realize that as the furnace is running, the inducer motor is pushing vent gases up and out of the vent pipe. Not all the condensate droplets in the pipe will utilize gravity to drain back to the furnace, some are suspended against the walls of the pipe as vent gases work there way out. After shut-down they will meander their way down and out.

It is important to maintain water in the black trap. It is meant to work as a trap and water will remain in there to prevent nuisance loss of pressure to the pressure switches, especially in low stage.

The inducer motor will get a bit of water in there, the impeller is designed to pick the traces of water up and flick it back into the header box. You will though know if you have issues if you actually hear the inducer motor loudly sloshing water, this is bad and a closer look at the draining network should be done.

It is important to verify that there is definitely no blockage of the venting pipe. Cutting vent pipe and feeding a rag taped to electricians fish tap and fed up and out or from out to in, is the best way to not only verify no blockages, but to clean any restrictive build-ups out of the pipe. IMPORTANT to first purchase a coupler from your local hardware store or mission band to reattach ends of pipe after you are finished.

Rarely will you find a blocked secondary coil, but it does happen. This is hard to verify and requires a technician with the proper tools.

Also, pressure switch issues are rare in newer models, but if your located at altitudes above 4500ft, may want to verify with your installer that high altitude pressure switches were installed. Technician can verify if the pressure switches are weak or falling out erroniously with a manometer.

These are some suggestions from my experience with G61 and G51 failure issues you may be experiencing.

As a Lennox Technician I feel basic repairs and maintenance can be performed by the homeowner. But I highly suggest that periodic maintenance should be made by a certified licensed technician. You should contact your local Lennox technician for any repairs or issues that are outside your comfort zone. Property damage, personal injury, and death can occur from improperly repaired or maintained systems. Replacing a part doesn't always resolve the issue that caused the part to fail!
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jkennedy99

3 Posts

Posted - 01/01/2009 :  3:11:22 PM  Show Profile  Reply with Quote
slctech, at least in my case, the furnace is an upflow vertical position. The condensate trap is on the same side of the furnance as the exhaust vent, and is located in the correct spot per the manual. I have about a 30 foot exhaust run to the outside with two 90 degree and three 45 degree turns. My furnace sits in an unfinished open basement.
When is gets very cold here, in the single digits, my furnace will run for a good hour sometimes, this is when my problems occur, and I do hear water in the inducer fan. It seems like water from that cold header box builds up and gets into the inducer.
"It is very normal for excess water to drain out of system after a heat call." I understand your point here, but no water at all (not even a drip) comes out of the cold header box rubber hose while the furnace is running. Is that normal? Other forums have stated it should be draining, and that condensate box is designed to let the water drain even though there is suction from the inducer fan.
BTW, I've had two different repair companies out several times and they have not been able to fix it (they've replaced the black condensate box though).
thanks for the advice,
Joe

jk
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MechAcc

1499 Posts

Posted - 01/01/2009 :  4:23:46 PM  Show Profile  Reply with Quote
It has not been mentioned but has the drain connection connecting to the drain trap been flushed with water? Was the drain trap flushed under a faucet or merely emptied of water? If emptied I would flush it under a faucet to make sure any debris is flushed out. Remember the condensate coming out of the furnace is only at a trickle and debris will collect in the drain trap. Other point to make is that I find many installs where the drain pipe from the drain trap to a drain has been reduced. Reductions in pipe will collect debris and cause water blockage.

I am not an employee of CozyParts. The opinions that I post are my own.

Please have your furnace inspected annually by a qualified service technician. Have all of your fossil fuel appliances tested annually for carbon monoxide production by a professional.

Get a good Carbon Monoxide Alarm. Replace it according to manufacturers recommendations usually every 3-5 years. CO concerns are not just for the winter but 24-7. UL approved alarms alarm high. For a low level alarm do a search for CO Experts or NSI 3000 a low level CO monitor.
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topher99

3 Posts

Posted - 01/05/2009 :  4:51:30 PM  Show Profile  Reply with Quote
So far my furnace has been working normal. I did pour 1/2 a gallon of water to flush the pvc line coming out o the trap. I also blew air through the res and black square hose that appear to go from a switch to the fan housings. I an blew air and drained all the drain lines on both sides. My furnace is a vertical install and the condensate trap intake and exhaust pvc are on the same side. We had warm up in temp and teh snow melted so I am waiting to see how things hold up after we get snow tomorrow. I'll keep you posted
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slctech

2086 Posts

Posted - 01/05/2009 :  8:31:42 PM  Show Profile  Reply with Quote
With the long pipe runs, how well supported are the lateral/horizontal pipes. Any possibility that there may be sagging in the pipes? Very important to keep a minimum of 1/4 inch per foot rise on the exhausting pipe so water can not pool and restrict the flue gases from backing up and snuffing the system.

I am just throwing out thoughts.....

How is this terminated outside? Two pipes exiting the home or both pipes running into a concentric kit (apparatus that allows both pipes to be joined into one larger termination for esthetic purposes)? If not terminated per manufacture directions, may be getting vent gases drawn back into the combustion air and this can cause erratic problems. Should not terminate under decks/patios. Should be above snow line. Should not be to close to extended walls of home or in areas that are effected by winds/drafts, like alleys or in tight areas between structures. If terminating out roof, is it above the snow line, any chances of flue condensation icing and clogging vent pipe?

The vent pipe should not have a bug/bird screen, only the combustion pipe may have this. This will cause icing on vent end and snuff out system.

On longer runs, the size of the piping is extremely important. The Lennox manual will outline what size piping in conjunction with the number of elbows is outlined.

Has the secondary heat exchanger been pulled and verified that there are no restrictions. This is a last resort issue, but if I was a technician having to return to a job, this would be on my list of things to check. A restricted secondary will cause erratic issues.

How much water is gurgling in the inducer motor? Is it a very quiet sloshing, or is it a concerning amount of noise that would lead you to believe that the inducer motor is really struggling to maintain RPM and pressure? If there is a concern with water in the inducer, it may become more progressive on colder days since the furnace is running harder and longer and can not rid itself of the water. Like I earlier stated, a little water is okay and normal, but larger amounts is not normal and should be dealt with.

Is there any possibility that the vent piping may be freezing? Is it running through any un-conditioned spaces. Possibility of system freezing in the mechanical room? This can happen when the cold air return is to large and placed to close to the furnace drain or drain trap.

Maybe a bummed pressure switch that is erratically operating.

What is your altitude? Above 4000ft? High altitude switch installed if this is the case?

I am sapped of ideas. Best thing to do is to make a personal log book of date, time, temperature (inside & outside), weather condition, snow depth, and wind conditions, at the time of failures. This will help see if there are any trends in operation failure.

Not all technicians have them, but we carry them and I use them periodically, but DataLoggers. This is a device that cam measure voltage drops, others measure pressure, etc. Have technician install these and leave them on for a week. These record digitally the current voltage and pressure readings. The technician can utilize your log book and download the info from the DataLoggers and figure out what is going on. Whether a pressure loss at the inducer, or a voltage drop from the board to the inducer. So on and so on. This would help narrow down the exact issues.

Good Luck......hope this helps.

As a Lennox Technician I feel basic repairs and maintenance can be performed by the homeowner. But I highly suggest that periodic maintenance should be made by a certified licensed technician. You should contact your local Lennox technician for any repairs or issues that are outside your comfort zone. Property damage, personal injury, and death can occur from improperly repaired or maintained systems. Replacing a part doesn't always resolve the issue that caused the part to fail!

Edited by - slctech on 01/05/2009 8:33:53 PM
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jkennedy99

3 Posts

Posted - 01/10/2009 :  11:27:27 AM  Show Profile  Reply with Quote
slctech, I read the lennox manual and indeed my exhaust termination was not 12 inches extend out from the inlet pipe. I added a 12 inch extention and have not seen the error code sense, however, it has not been as cold recently either. On the water question, when I heard water in the inducer fan, the fan was struggle to work, and the top of the fan was extremely hot (maybe that is normal?). I also pulled off the inducer fan, looked into the hole at the secondary heat exchanger and saw no restrictions (but my view was limited and I did not feel comfortable taking out more parts)
I have rechecked the drain from the secondary inducer by pulling off the black rubber tube which drains water from the exhaust pipe. By doing this, only the rubber tube from the seondary inducer was attached to the black consendsate box. So, what I saw was a slow drip of water coming out, and when the furnance shuts down several ounces of water poured out. Based on one of your previous posts, do you think this is normal/ the way lennox designed it? Maybe I'm just over thinking it.
thanks for all the advice,
Joe

jk
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slctech

2086 Posts

Posted - 01/10/2009 :  11:55:12 AM  Show Profile  Reply with Quote
The inducer motor does get hot, and you will hear some gurgling hear and there, usually upon start-up. If water is an issue getting into the inducer you may have a restriction/clog at the main drain tube. Right where the main flue pipe connects into the furnace, you will see the larger black tube that runs from the bottom of the flue pipe, right on down to the drain trap. This is designed to allow returning condensation to drain right into the trap, if slightly clogged or restricted, then the water will start to bypass this and go right down into the inducer motor assembly. Triple check this is not the issue.

Other forgotten about item, is related with the original install. The furnace should have been set with a slight slant from back to front, so water doesn't get trapped in the secondary exchanger. This is not a huge issue if the furnace is perfectly level, but if the front is set higher than the rear, you will have erratic issues.

I think you may have found the issue outside. When you are recirculating flue gases, the furnace is literally sucking in moist condensating air. This will dramatically increase the internal amount of water generated and the system can not keep up. Also recirculated air throws off the balance of oxygen to air ratio at the burners and you get incomplete combustion...damages heat exchanger, snuffs burners (when oxygen level drops to low).

Be interesting to see how things go...keep us informed

As a Lennox Technician I feel basic repairs and maintenance can be performed by the homeowner. But I highly suggest that periodic maintenance should be made by a certified licensed technician. You should contact your local Lennox technician for any repairs or issues that are outside your comfort zone. Property damage, personal injury, and death can occur from improperly repaired or maintained systems. Replacing a part doesn't always resolve the issue that caused the part to fail!
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AJAE

1 Posts

Posted - 11/26/2010 :  02:13:17 AM  Show Profile  Reply with Quote
This has been a helpful thread. I have a similar issue on my furnace getting error codes 2+3, 2+4, and 2+5.

I did drain the trap and I also removed the Low Fire switch and emptied the water out of it. Yes, there was water in the switch, which I don't think is good. The red and black tubes that go to these switches are horizontal or down from the inducer housing so I'm guessing that any water being flung around in their may make it into the tube and into the switch. It was only about a teaspoon of water but disconcerting at best.

Installation is a vertical-down. Furnace is level, drain and supply and exhaust all on same side.

Some crud in the trap, but not a lot. Light gurgling sound when furnace is running, appears to drain. My condensate drain goes right into the drain pan I have form my hot water tank, so I can't see the end of the pipe exactly to see how much it drains.

Curious, I did hook up a length of surgical tube to the trap clean-out (lower hole) to drain it initially and then left it hooked up. Furnace ran for a while and I figured it should be draining but it wasn't. So I gave a very short 'suck' on the end of the tube to encourage the flow and presto, another cup of water came out.

Then I had an error a little later with the drain empty (2+5) so I moved the tube to be higher than the trap thus preventing any further draining and the error code went away.

I think the low-fire switch is either damaged or being damaged by water coming from the inducer fan.

I moved the low fire switch up a bit by simply unscrewing it and moving it to a higher hole mount to give the red and black tube some upward bend before bending down into the switch. I hope that will keep water from draining into the switch.

Any other thoughts? I still think there is something very finicky or even not quite right with the drain design on this furnace; it just seams to precise and prone to failure. I haven't yet checked for blockages in the condensate drain after the trap, I wonder if it's constricted enough that the water simply backs up the hose to the exhaust and into the inducer fan.



G61MPV (2009)

Edited by - AJAE on 11/26/2010 02:23:09 AM
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