Heat exchanger failure diagnosis, Goodman GMP model

[@Larrye123]

Four hvac classes under my belt and this is the first time I've heard about allowing some time to pass while observing the heat exchanger for a crack. We normally waited until the blower went on and then made our decision based on a change in the flame. I see that waiting is important. Thank you!

[@grayfurnaceman]

Welcome GFM

[@cindyschmolze4599]

I cannot find the answer you sent me about my Carrier heater (14 years old), but I did want to get back to you and say a great big THANK YOU for helping educate me about heat exchangers and putting me on to the possibility that my particular unit may have been involved in a recall. I contacted Carrier, and indeed, although not a recall, because of problems with the secondary heat exchanger, they have given a lifetime warranty with full labor included on it. There is a lifetime warranty, without labor, on the primary heat exchanger. This is huge in helping me make a quality decision about replacing my heat exchanger in the near future! You're the greatest ~ thanks for your service to novices like me!

[@strongirish6330]

I'm a residential HVAC service tech,last week I just found one of these and all three bends at the first 90° down were huge holes in the exchanger...Yes these furnaces can be bad news for a homeowner.Good Video:-)

[@grayfurnaceman]

They started out piping the rivets which allowed the clamshells to separate, but lately the have cracks near the rivets, so yes they are bad news. Thanks for the thoughts. GFM

[@mikeantj]

I literally just got back from a no heat call on a GMH95 with a tripped limit switch. I checked virtually everything, heat rise, pulled the cover to check for a dirty coil, pulled the blower to inspect the heat exchanger. However the flames looked exactly as you describe, no co2 detectors went off and the furnace would run for about 30 mins before tripping. I condemned it until I can further inspect but they have a furnace for the 1st floor and a very open living space. The thing that got me was the flames stayed the same even when the blower kicked on but I was reading 195 degrees near the 200 degree limit switch . Thanks for the video

[@grayfurnaceman]

When there is a large expense on a furnace that has reached over 20 years old, I would always consider replacement. Heat exchanger costs for parts and labor could be $5 to 800. However, there are other considerations. If the heat exchanger is under warranty the charge will probably only be for labor. The owner may want to replace the furnace for higher efficiency. They may need the cheapest repair. The pay back is usually quite long. Newer furnaces have higher repair costs. Thanks GFM

[@joelschultz3652]

Came across two of those exact model numbers today and they were made in 2000 so they were not discontinued. Both were done for. One was blowing 4000ppm and other 400ppm of CO.

[@grayfurnaceman]

I love it when guys send me vids. It helps so much. Looks like a heat exchanger to me. Some of these units now are cracking the heat exchanger in addition to popping off the rings. Definitely change the heat exchanger! GFM

[@jrrains]

I am a hvac technician and my company warranties old hvac units. Yesterday I replaced a heat exchanger on a package unit natural gas pack. Install when we'll however after ignition we had heavy white smoke coming out of flue. The gas pressure at valve was good everything operated properly. However it continued to smoke heavily. Also the smoke begin as soon as burner fired off before exchanger could really get hot. Any thoughts? Maybe packing materials fell into burner tubes?

[@grayfurnaceman]

@@jrrains Could be. Many manufacturers leave an oil from the manufacturing process on the heat exchanger that smokes. GFM

[@jrrains]

@@grayfurnaceman yes this one smoked for hours and I have to return today to see what's up. Maybe to much oil who knows.

[@johnisraelhvac2019]

Great video GFM!! I'm changing out this exact furnace Tuesday!! Went and did maintenance check last week and it was doing exactly what this one is!! The flames weren't rolling quite as bad as this one!! But they doing exactly like this!! Great Video!!

[@grayfurnaceman]

Israelhvac These boys were known for that. The biggest problem is you can't find a crack in the heat exchanger because the rivets holding the clamshell pop loose and the 2 halves spread apart. GFM

[@europeanauto1020]

That was kind of what I thought would be your response. Thank you so much. Thank you for your quick response also.

[@grayfurnaceman]

This rollout is very subtle. A very close eye on the flame is necessary. It should be fully rolled out in 2 min. Hope this helps. GFM

[@grayfurnaceman]

I believe it does, although I cant be sure. I would remove the top and check for the loose rings as in the GMP models. Hope this helps. GFM

[@paulfalcone4115]

Thanks for a great demo, confirms my suspicions , # 3 of 3 burners was rolling out, tried to clean everything etc. looks like a teardown. Thanks again for spreading the knowledge. Be Blessed. Paul

[@johnnyprotalk3352]

Once again gray furnace man very informative video 👍

[@mnalep2]

Thank you for the video. My furnace has the same symptoms. You videos and web site are great.

[@grayfurnaceman]

What are you trying to clean? Blower, heat exchanger, burners? GFM

[@jeffsworld2]

I had one of these furnaces about 10 years ago in a condo that I purchased. The previous owner had told me about this issue and that just the heat exchange was replaced. I never had any issues with the unit during the time I lived there.

[@bshivanand1]

I have carrier weather maker 8000 HVAC unit. Last smmer I replaced control board with ICM282A as one of the relay has burned out and there was ice formation in the AC grill. Come November, we switched on the heater. The heater worked for 10 minutes and tripped shut the unit down after 10 minutes. I raised thermostat temperature to 79 thinking the temp setting too low. the problem repeated. I cleaned flame sensor, and other sensors in the unit.

[@laforgia1]

Thank-You for the video. I think I may have a similar problem. I bought a Bacharach Snifit mod 50 to see if it would detect any CO coming from the vents up stairs or near the return. I don't get a reading at all but I have noticed my windows getting dirty on the inside. Your video convinced me to check out the burners and the heat exchanger.

[@grayfurnaceman]

Sounds like an air flow problem. If the unit vents with plastic pipe, the secondary heat exchanger may be plugged. The blower wheel should be checked for dirt. Is the blower turning the correct direction? Certainly a cracked heat exchanger could cause the problem. It may take a very thorough exam to find the crack. You may remove the blower and look up at the heat exchanger. If you send me a model # I may be able to give more specific info Let me know what you find. GFM

[@picklerix6162]

I had a 1993 GMP100 Goodman gas furnace for 27 years matched to a Lennox 12 SEER 5 ton condensing unit and Lennox coil. When I replaced the furnace in March 2020, the old heat exchanger looked great with no cracks or popped rivets. My Lennox evaporator coil looked great too and I was shocked that it had never leaked. I replaced the HVAC equipment because the compressor shorted to ground so I installed a new Goodman 16 SEER condensing unit, coil, and GMVC80100 gas furnace. I was little shocked that my electric bill during the summer dropped from $320 to $170 for a 2900 sq ft home in the South. My neighbor across the street told me that her A/C has not been working correctly. She told me that her electric bill was over $500 in July and she lives in a 2200 sq ft home.

[@grayfurnaceman]

Comparing electric bills is useless. There are too many variables. Even if there is a boost in efficiency (there probably is), it will be in the 20% range, not 50%. GFM

[@kahvac]

Excellent video ! To the untrained eye it is easily overlooked. I might of overlooked it myself. A tripped rollout switch would be a dead giveaway but sometimes techs overlook that too. Great video thanks again.

[@grayfurnaceman]

This problem, while not limited to the Goodman, is fairly common with induced furnaces with small cracks. GFM

[@tjl8884]

Run the furnace fan without the flame on and put a lit match up to each hole.. If the match goes out or moves excessive its because the exchange is cracked and drawing air in .. A long candle would work too.. Just make sure your not running the heat on mode, should be fan only mode..

[@bshivanand1]

Continuation 2: I opened up the unit and cleaned burners vacuumed heat exchanger tubes. I also vacuumed air handling unit. I also checked inducer fan for any debris. did not see any debris there.Pu all parts back. Fired up the furnace.Same problem continues. I also checked the exhaust flue pipe that goes into the roof. Found no blockages. The problem is, Exhaust flue gas pipe heats up enormously high and shuts the unit down. The control board led error code shows 33.

[@aircooledtx]

Replaced bunch of these in Keller,Tx. 10 year warranty heat exchanger; so made recommendation for new furnace change, most went with Amana or Am-Std. I talking about whole sub-divisions with exact same problem, did average of 3-4 a week.

[@grayfurnaceman]

Pretty common around here too. GFM

[@europeanauto1020]

Thank you so very much for your knowledge and for sharing it. I have a GMP, the unit hasn't been used in years. I keep getting a limit switch code (4 blink). My flame looks good even after 15-20 minutes of running (I have to jump the switch), but my temperature near the switch when running has gotten up to 215° after the 15-20 minute run. The temperature after the inducer motor is running out at about 230°. I have taken out the filter completely and made sure that all the vents are open and blowing. I have replaced the sensor with a new original one with no change. It seems that the blower is working, and a fair amount of air is coming out of all the vents. Any suggestions as to where I should go from here? Thanks again for your videos.

[@grayfurnaceman]

If the limit kicks off and you have good air flow [you appear to], you have a failed heat exchanger. Dump it. GFM

[@grayfurnaceman]

First, check warranty status of the heat exchanger. Flat rate pricing for hot surface ignitor should be $140-160. If heat exchanger is under warranty, it is labor only for replacement. I usually did those in 2 sometimes 3 hours. New is always better but can be expensive. In the northwest we would do an 80% efficient furnace $2000-3000. Hope this helps. GFM

[@derekddurbin]

I smile every time I see these furnaces

[@martyyates6754]

hey, i was wondering what is the best way to clean out a westing house 70% furnace?

[@bshivanand1]

Sorry about the delay. Could not get to the attic as we were upgrading kitchen and entire carpet replacement. The unit was running as one of the opening made by mechanic opened up in the air handler and there was enough ventilation to cool the furnace. I opened the piece (12 inch x 10 inch) re-installed with some outside reinforcement by screwing a board and taping with aluminum tape. I also applied putty paste. started furnace. It is working. The ambient and set temp diff is 3 degF.

[@seshachary5580]

very educative. Thank you regards

[@blondv007]

I have a GMP 100 and I had two techs check it out.My igniter is bad,so it wasn't running when they checked it.The diagnosis was a crack in the exchanger and a bad igniter.They want me to purchase a new system or pay half to fix it..What do you think is a good price for either fixing or replacing.the system is about 11yrs old

[@brailosky15]

what if the flame look normal but the rollout switch get trip and i got to rested manually?

[@grayfurnaceman]

If your reset is opening repeatedly, you almost certainly have a cracked heat exchanger unless the furnace is overfired. GFM

[@bshivanand1]

Continuation 3: I reduced gas intake by 50% by turning gas valve. The unit seem to be holding on and working. House is heating well. I am wondering could there be CRACKED HEAT EXCHANGER. I could not detect any crack with flash light. Appreciate your help. Thanks in advance.

[@stephendvorak060075]

great video i have 2006 gms95 goodman furnace and it is doing this exact thing do you have a follow up of this video on how to replace a the heat exchanger. goodman.

[@grayfurnaceman]

I did a playlist on these furnaces that may help. kzbin.info/aero/PLItXrh64d2JN70Me2o9ADb-lCkrkmJCXl&action_edit=1

[@svaldez0209]

If your heat exchanger is cracked, is it wise to just replace the whole system or just the heat exchanger? how much does a heat exchanger cost to replace?

[@Blocksguyoldchannel]

Do you know what a janitrol gmp125 is

[@grayfurnaceman]

Its an 80% efficiency, 125,000 BTU furnace. GFM

[@Blocksguyoldchannel]

Will you ever make more video on this furnace

[@grayfurnaceman]

There are 2 playlists on this furnace. Here is the first one: kzbin.info/aero/PLItXrh64d2JN70Me2o9ADb-lCkrkmJCXl GFM

[@toddberner761]

the problem does not seem to occur til supply fan has engaged.

[@scottc.6409]

Are there any gaskets involved with this unit?

[@marshallandroxy]

I have a GMP075-3 REV A - The serial begins with 9710 which I believe means 1997, October - is this as bad as the non-REV A in your example? My heat exchanger has the blue flames in between like you say is normal in the beginning of the video, but does not have the roll out yours exhibits in the video. I'm guessing I'm fine for now?

[@grayfurnaceman]

I am not sure on the revision. From what experience I have had, the date code is past the problem heat exchangers. If there is no evidence of rollout or rollout switch opening, I would be sure I have a CO detector and check it every heating season. GFM

[@stevencarrillo3615]

Thanks learned something new.

[@stevergee]

Do you have video yet to show how to remove the bad heat exchanger and replace with new one?

[@grayfurnaceman]

+Steve Goettler I have not done one. It is pretty straightforward if you have good mechanical abilities. GFM

[@stevergee]

+grayfurnaceman excellent then, my HVAC guy he should able to get another one under the warranty and I think he should be fine to let me put it in myself

[@js0009]

Does this affect gas packs in the model year range?

[@stevero2581]

I got an american standard package unit can't see with cover on. Any suggestions. Tripping a good rollout. Intermittent problem. Heating up heat exchanger first makes sense. Great video

[@grayfurnaceman]

If the rollout is opening, you probably have a heat exchanger problem. Either blocked or cracked. GFM

[@stevero2581]

@@grayfurnaceman thx I thought so. What do you think of match test. Match in front of burners with fan on only?

[@grayfurnaceman]

Sometimes that works and sometimes it does not. I will be doing a video on this method in the future. GFM

[@stevero2581]

@@grayfurnaceman thank you

[@tompietrzak270]

Thanks for sharing this grayfurnaceman I have a GMP 100-3 that was installed in 93. Thought I had problems with the blower motor but when the tech came out he said it was the heat exchange. He demonstrated similar flames multiple times. Probably just going to go with a new furnace for $2500, doesn't seem to be worth repairing/cleaning after reading all your posts/comments.

[@gwpiker]

is it possible for the flames to distort enough to lose contact with the flame sensor? I'm running into this issue, Amana package unit runs for a while then loses contact with the flame, when I ran my meter in series with the sensor I noticed it basically counted down to zero once the door was reinstalled..

[@grayfurnaceman]

They can. This sounds like a venting or combustion air problem. GFM

[@captainnemo3549]

Hi there, have a model GMP 100-3 ,is shutting down before reaching temp and no error codes are present. Replaced thermostat and still doing it .Any thoughts ?

[@grayfurnaceman]

Are you sure the unit is not limiting out? GFM

[@captainnemo3549]

@@grayfurnaceman thanks for replying back , I can check on that however ,no error codes whatsoever .Thanks

[@fredredd410]

I just changed my blower motor and limit switch on my GMP075-3. I noticed my burner flames were rolling out like in your video. I have CO detectors but they all show 0ppm. The rollout switches haven't tripped. No idea how long this has been going on for. There's a crack in the faceplate where the holes for the flames are. How concerned should I be?

[@grayfurnaceman]

Very concerned. The crack in the faceplate is also considered a crack in the heat exchanger. GFM

[@airbizzle_diesel5228]

Having issues with mine not receiving gas to ignite

[@grayfurnaceman]

Sounds like a safety shut down. What code is shown on the control? GFM

[@airbizzle_diesel5228]

@@grayfurnaceman solid red light

[@grayfurnaceman]

@@airbizzle_diesel5228 A solid red light on an IFC control means the control has failed. If it is an ignition control (made before 1992), it just means power to the control. GFM

[@grayfurnaceman]

@@scarey313 One blink on Goodman means ignition failure. If the burners never come on, and the HSI warms (glows), that could be a control board (IFC), or gas valve. If you replaced the IFC, and the burners came on, then the service tech found indications of a failed heat exchanger, he could not have known that before the burners were operational. GFM

[@averyalexander2303]

Great video! I have a question. I just bought a house that has a Goodman GMP075-3 furnace like the one you show in the video. It is rusty and I needed to repair a few things in it to get it working correctly. Mine was made in 1993 and seems to work fine now that I fixed it. It looks like it is burning well, and the flame is not rolling out or anything. I called the gas company and they did a free inspection and they said it's safe to use, although they never did a CO test. I also have a good CO detector with a digital readout that always reads 0., so it's at least not producing massive amounts of CO. Would you be concerned about this furnace? I could pull the heat exchanger and visually inspect it if you think I should. Thanks.

[@PadraicPlaugher]

huh, never seen that. Usually the flame just gets blown out!

[@raiderman28]

My flames are doing the same thing, then the whole unit shuts off. Is it hard to replace the part if it's cracked??

[@grayfurnaceman]

+Raul Romo I can do one in about 2 hours, but I am a professional. The furnace must be pretty much dissembled. Take pics before. Hope this helps. GFM

[@raiderman28]

+grayfurnaceman my flames do the same thing, but my blower never comes on. I tried replacing the limit switch, but had the same problem. the burners come on and blower never comes on, then the burners turn off, and display on thermostat shuts off, only fan that comes on is the exhaust fan on top, the blower never comes on. any suggestions???

[@grayfurnaceman]

+Raul Romo Check to see if the blower wheel will rotate easily. If the motor is hot after trying the start, the motor has failed. You could also have a problem with the control board not sending power to the motor. GFM

[@raiderman28]

+grayfurnaceman cool thanks. Will try and check that

[@mikhaielj846]

Steve Do have a video on Combustion analyzing and how did you Adjust the gas valve without a Manamoter ?

[@martyyates6754]

just the heat exchanger, great video!

[@jackmacgregor5586]

Is the GMP125 model also known to have heat exchanger problems?

[@vladtom68]

Great video and great advice.My furnace filter after two months is black,would this be a sign also of a heat exchanger going bad?Thank you

[@grayfurnaceman]

Probably not. Do you have lit candles in the house? GFM

[@vladtom68]

no,but I did have some candles lit over the holidays,thank you very much,you are one sharp cookie!!Will change filter and keep an eye on it

[@RevWoody]

I have a 95070. I don't see the flames rolling out, but it is really loud... Like a pulsing, cavitating noise. Any ideas?

[@grayfurnaceman]

Josh Woods There could be a problem with the inducer. Also, I would check the gas input rate. However, some units that do this we never find the problem. GFM

[@averyalexander2303]

Hey GFM, I am wondering if it's possible for a heat exchanger to only leak when it's cold. I have a furnace just like this from 1993, and it has a different problem. It has trouble starting up when it's cold. Right after it starts up, the left burner goes in and out, and sometimes the furnace shuts down. However, once it runs for about 30 seconds, it runs perfectly fine, and it continues to run well until it shuts off. I checked the input and output gas pressure, it is good. I checked the flue pipe and cap for restrictions, also good. Then I removed and cleaned the burners, and it still does the same thing, Could this be caused by a bad heat exchanger? Thank you very much in advance!

[@grayfurnaceman]

It could be. Heat exchangers do not have to leak only at high temps. GFM

[@averyalexander2303]

@@grayfurnaceman Thank you for your help. I tried starting the furnace with the blower motor unplugged, and it starts fine, so the heat exchanger is bad. Makes sense, I have seen exhaust manifold leaks on cars that seal themselves once the engine heats up, so this probably isn't that different. With the amount of rust in this POS, I would be surprised if the heat exchanger wasn't bad. And I am not going to put that much money into this old POS. Since I bought this house 3 months ago, I already had to replace the crappy plastic flue pipe connector, the flame rod, and the inducer, and the IFC is also bad and needs to be replaced since it has been setting a pressure switch code since I moved in even though the furnace runs and the pressure switch is good.. Time for a new furnace

[@grayfurnaceman]

Sounds like it. GFM

[@averyalexander2303]

@@grayfurnaceman Do you have a suggestion for a high quality furnace that is a similar size? I like Trane equipment, but I don't think that they make a furnace that is this small, and it can't be any bigger because is in a very small room in my hallway, and this furnace barely fits as is. It is literally so tight that I had to take the door frame out to have enough room to get to the gas cock to change it. Thanks

[@grayfurnaceman]

Yeah, the first on is the hardest. I did so many of them that I could sometimes diagnose them by hitting the side of the furnace and listening for the bounce of the rings on the shelf. Quick fix though. Often could replace heat exchanger in less than 2 hours including diagnosis. Thanks. GFM

[@ncut5547]

I ges that 11wc is with the furnace running just checking thk u

[@grayfurnaceman]

Yes GFM

[@HVAC-ln4vg]

Great Video!.. keep them coming.

[@chiwoody48]

Excellent example. Thank you.

[@grayfurnaceman]

Welcome GFM

[@loungelizard836]

Thanks for the video! I've got an old rooftop package unit and found a crack in the heat exchanger after I found it had set off the "roll-out" switch (on mine it was an overtemp circuit breaker). Not the same furnace, but similar problem and it all makes sense now why I would have to keep resetting that breaker! Mine is toast (I figure they aren't worth repairing?).

[@grayfurnaceman]

J Bishop Usually not. Go for the new one. GFM

[@scottc.6409]

Very good video! Do you have a video on replacing the heat exchanger? Thanks!

[@grayfurnaceman]

I have never done one. Sounds like I need to do another video. GFM

[@grayfurnaceman]

You do not need any gaskets as you can use hi temp silicone. GFM

[@scottc.6409]

@@grayfurnaceman Thank you! Where should I expect to put the Hi temp silicone? My guess wold be around the flue collector box behind the inducer motor. I have the exact same model.

[@grayfurnaceman]

@@scottc.6409 You are correct. There is a fiber gasket between the inducer housing and the manifold. I just remove the gasket and use silicone for a gasket. GFM

[@scottc.6409]

@@grayfurnaceman How long should I let silicone dry before firing off unit?

[@mrofnocnon]

I have never understood how the American gas code allows a flexible gas connector, especially one that passes through the casing to be allowed. Also when the spill or rollout switch shown above in the video trips open it has a manual reset that indicates a possible problem with the heat ex. It will not work as well with the furnace front door being off.

[@grayfurnaceman]

It does not allow flex lines thru appliance casings. The furnace you see in the video is a test mule. Used for testing only. GFM

[@mrofnocnon]

Good to know.

[@TheTerminator1919]

Excellent video

[@grayfurnaceman]

Thanks for the support. GFM

[@John-lr9gp]

What causes an unstable flame on a lp. Gas furnace

[@grayfurnaceman]

By unstable do you mean flame rollout or burners no lighting completely or flame rising from the burner? GFM

[@CommonSenseFishing209]

The sooting/ corrosive debris around the burners should give you a concern. Cva is off or gas pressure or heat exchanger.

[@grayfurnaceman]

The corrosive debris is from flame rollout due to failed heat exchanger. GFM

[@CommonSenseFishing209]

@@grayfurnaceman yep that effects cva. Same thing. A problem in the combustion process is what causes corrosion wether a cracked heat exchanger or not

[@grayfurnaceman]

A bit simplistic. Sooting is very rare in the natural gas furnace. Overheat is the most common issue causing heat exchanger problems. Also reactions from plastics used in secondary heat exchangers cause corrosion. Low firing rate is also a big cause. Modern gas furnaces have no adjustments for primary air so proper manifold pressures are the only way to adjust fuel air mixture. I have also seen both too much and too little primary air in older furnaces with no damage to the heat exchangers. GFM@@CommonSenseFishing209

[@CommonSenseFishing209]

@@grayfurnaceman your right for natural gas for propane it's very common. Plus I noted the other causes like cracked heat exchanger etc. Each climate and area has its usual culprits due to temps and humidity or lack there of. Also bad cva or gas pressure causes corrosion. Not the flame rollout your showing. Flame rollout is almost always a cracked heat exchanger or on a 90 plus percenter a plugged heat exchanger. Or vent problem with flue or inducer.

[@awatkins777]

Thanks for the video. Would it have trouble igniting? I ask because I had a guy out today saying my exchanger was bad and it also has trouble starting. It's a GDS80703ANA I know it's not the one in the video.

[@grayfurnaceman]

It could have trouble igniting depending on where the crack is. GFM

[@AwakenedOne-qu]

Good Vid, well done.

[@grantw.whitwam9948]

Great vid, thanks. I don't have this furnace brand.

[@grayfurnaceman]

They are probably not going to be good on this. There were enormous numbers of failed exchangers. I remember something about 15 years on the 80% furnaces. I wish I had better news. Maybe a call to BBB? GFM

[@ericgordon8542]

My mothers heat exchanger is cracked, why not replace the heat exchanger?

[@grayfurnaceman]

If the heat exchanger is available, you can. What commonly happens is that if the furnace is over 20 years old, its life span is only 25 years. GFM

[@4232ist]

do you have a video on how to replace a furnace heat exchange on this model

[@grayfurnaceman]

+lester mcgee I have not done one. However, it is one of the simplest ones to replace. Take lots of pics before you take it out. GFM

[@4232ist]

thanks

[@stevergee]

+lester mcgee did you replace your heat ex-changer? I am about to figure out the same thing. Furnace stopped yesterday ... traced it to a melted roll out switch wire that had shorted. I broke the roll out switch trying to pull the wire off so I temporarily connected them and got the furnace running again. - But it appears i am getting some blow back flame activity into the burner area and that is why the wire melted - thus we seem to have a heat exchanger issue

[@grayfurnaceman]

+Steve Goettler The furnace I did the video on had the failed heat exchanger. This is why I used it. It was a garbage unit. The heat exchanger can be replaced, but I would consider replacement of the furnace. Hope this helps. GFM

[@4232ist]

no i didnt half to it was ok.

[@mnalep2]

So who do I call to get the warranty coverage? The heat exchanger is under 20 years old and there is a warranty certificate indicating the exchanger is covered for 20 years, How long would it take, a non-HVAC guy like me, to replace the heat exchanger?

[@grayfurnaceman]

mnalep2 I would look for Goodman/Janitrol dealers. You could change it in about 3 hours. Take pics before you tear it down. GFM

[@djhuart8454]

Great video GFM, thanks for posting it. I have one of these GMP furnaces, also horizontal in my attic. My inducer motor is toast, but the tech also noted these furnaces heat exchanger's have a high failure rate. Is there anyway to tell if my HE was replaced under warranty by looking it? PN perhaps? I have not done this flame test, since the furnace won't run. My predicament is spend the approx $200 to replace the inducer motor and fan which can be done sooner obviously, only to do the flame test you show here and find the HE is also bad, or put the 200 towards a new furnace that won't get installed for a week. I'm in Ohio and the weather is turning really cold soon. I will say I have 2 CO detector's (fresh batteries as of Halloween) in my 1000 sqft single floor house, neither in the drafty attic though. Neither has alarmed ever in the 2 yrs I've had them.

[@grayfurnaceman]

+Dj Huart At this point replace the furnace. It has many years on it and there is no way to determine if the HE was replaced unless it is noted on a service sticker. GFM

[@djhuart8454]

+grayfurnaceman Thank you GFM, you've helped me make my decision sir. New furnace hopefully Friday. I found three ring, so this old clunker is outta here asap. Thanks again for your informative videos, safety first!

[@grayfurnaceman]

+Dj Huart Good decision. GFM

[@patrickhogan4196]

Great video...I need a Heat Exchanger for a GMS90703BXA and am having trouble finding one...would you have anyone you use for this? I live in IL. Thanks

[@grayfurnaceman]

Some of those parts have been discontinued. You may be stuck. GFM

[@patrickhogan4196]

i did find 3 cell exchangers on Goodman repair parts,just can find a match or cross reference.

[@grayfurnaceman]

Patrick Hogan Are you sure you are looking at 90% efficient furnaces like yours? GFM

[@rosssalupo7271]

very informative thanks for the education

[@blipco5]

Great video. I think my 90's vintage Goodman has a plenum leak. What do you think of the newest Goodman furnaces of the same design? Have they addressed the weak plenum issue?

[@grayfurnaceman]

I have not seen any problems with the newer systems. GFM

[@blipco5]

Thank you. My current unit is the GMP 100-3. I am hoping to replace it with a similar physically sized unit for simplicity.

[@geojor]

practical video, thank you...

[@YTsux24-7]

I've seen these flame rolling out issues happen on newer furnaces on several occasions. Turned out to be the Bvent cap was shoved down too far by a roofing contractor. Be careful condemning a HE without inspecting the vent termination.

[@raiderman28]

I have this exact model. but my blower never comes on. the board shows 4 flashes which say limit switch or aux switch. I took fan off and checked fan directly and it works. can I just bypass limit switch to see if fan comes on, to make sure limit switch is bad???

[@grayfurnaceman]

+Raul Romo You probably have with a limit stuck open or a rollout switch open. The rollouts have a manual reset button on them. I would try resetting the rollout(s). When you do this, watch the burner flame closely. You very probably have a failed heat exchanger. The flame will rollout the front. Hope this helps. GFM

[@raiderman28]

I looked at the manual resets. there are 4-5 of them. none of them click down, so I don't know if they actually tripped. I will have to take a meter and check them. the limit switch showed continuity when I checked it, is that normal??

[@jeffscherm6474]

Thanks for the video. I have the same model almost GMPN080-4 1993. Wow, I did not realize I have been living here so long. I have the exact problem with my far left burner only of 4. If I work my heat up slowly it does not set off the roll off switch that shuts down everything. The fan does not continue to run .I have removed the burners and inspected with a flashlight and can see nothing wrong. I am going to take it apart. I see a gasket around the black plastic box the blower is attached to. Is this salvageable? I've seen people say this could be caused by a clogged secondary exchanger. Is that possible? I really dread ripping this thing down and putting a new primary heat exchanger in to find out I still have the same problem. Thanks again for the video and help

[@grayfurnaceman]

The gasket can be replaced by hi temp silicone. The GMPN is somewhat different than the GMP. A clogged secondary heat exchanger can, in some cases cause this problem. When I have done them, both heat exchangers are replaced. GFM

[@jeffscherm6474]

grayfurnaceman Thanks for the quick reply. I am just handy enough to be dangerous. I am now in a dilemma. I have little money thanks to downsizing in my previous company. Or right now I am cheap which is not good when it comes to ac/heat. Anyway, I've priced the parts at about just under 400.00. I can rip out the furnace which is part of an ac/heat system and replace it for about 800.00. I can brake metal and reduct.(a little) I would like close to an exact fit. 1 just replace heat exchangers on a very old system. 2 replace just the furnace or 3 replace the whole ac/heat system because it has lived out it's useful life? Which would you choose on a limited budget? Thanks

[@grayfurnaceman]

If the money is short, the heat exchanger is the cheapest way. There is a chance of further failures but that is the choice. As for the A/C, if it ain't broke don't fix it. GFM

[@jeffscherm6474]

grayfurnaceman Thank you so much for your help and advice. The money is short but I do have a credit card for emergency use such as this. I am not quite a trillion in deficit yet.One day I hope to get a better job and start reducing that deficit. Jeff

[@jeffscherm6474]

grayfurnaceman I wanted to thank you again a say you are a rare breed. It's hard to find people that are willing to help others out for no reason other than just helping their fellow man(kind). A stranger at that. Thanks again. I am going to share a story and ask if malpractice is required in your field? I bought a house in WV about 10 years ago. It was full of soot everywhere. No CO detectors in house. It was on the market for years as no one wanted to clean up such a mess. I got it cheap. Was told the previous family had died not how though. New owners distant relatives kept the heat on to keep the pipes from freezing and problem with furnace causing soot to back up into house. Supposedly the furnace was checked by contractor but when I got house the furnace was torn apart all components lying on floor in basement. Ordered installed new furnace a little re-ducting return air and had it back together. Fired it up and 20 seconds later it shut down. There was a power venter out the side of the house for exhaust oil furnace. I got wiring diagram from manufacture of power vent and reconnected it properly. It was wired wrong and bypassed the draft sensor. Somehow the squirrel cage had disintegrated except for the ring and allen screw holding to the shaft of power venter. Installed new squirrel cage fan and everything worked fine including AC which I had no idea if it would work. So now one little may two wires I can't remember connected to the wrong circuit allowed the furnace to keep operating bypassing draft sensor so there was no or very little exhaust. Filling the home with CO and eventually soot probably killing them. Malpractice? Now until finding your video I was going to fix my problem with a higher temp rollout sensor. I ordered it but could not find it. Subjecting me and my family to possible CO. Now you are a life saver.

[@404-e5b]

Learning a lot. thank you!

[@grayfurnaceman]

Merry Christmas GFM

[@hvactecster79]

I always call it "the highly experienced, been there and seen that opinion",LOL. Great video of an old ghost horror story. Take care, Brett

[@jemusalem]

GFM, while replacing my GMP100-3 blower motor I did find one crimp ring (ID=1/2") in bottom of blower housing. Per your video I looked at the flame with old and new blower motor...it looks fine. Should I still suspect my heat exchanger is bad or is going to go bad?

[@grayfurnaceman]

I would be concerned unless the heat exchanger has already been replaced. This failure can be very subtle at first. GFM

[@toddberner761]

a lot of the exchanger issues stemmed from the style of burners shown here with the adjustable air shutters....they were very sensitive to adjustment, could caise combustion issues, and were to be removed for propane applications. the replacements are the open venturi style Goodman uses today.

[@grayfurnaceman]

Good info. Thanks for the thoughts. GFM

[@pheelmob]

i had a call the other day for a roof top unit and the problem was that the customers in a phone store could smell natural gas coming through the vents it was something ive never seen the gas valve went right into a inducer motor and when the system did its sequence but when the gas valve came on i could smell a abundance of gas right there where it went into the inducer motor which i have never seen before this type of design and i didnt have a manometer to test the pressure bc the gas valve released a negative pressure so i needed a digital manometer go figure so the only thing i could think of is the gas valve is releasing to much gas or the heat exchanger is cracked i could def use some help on this one

[@grayfurnaceman]

PHEEL MOB I am assuming this is a Trane Voyager unit. Some of these units did break heat exchangers. Remember this one has a pressurized heat exchanger. Thus the gas smell. And yes, it has a negative pressure gas valve. If you remove the top of the unit, it is easier to check the heat exchanger. The ones I have seen cracked at the front end. Hope this helps. GFM

[@pheelmob]

Good to know bc I was wondering how I was gonna inspect the exchanger I'm going back Monday to look further in to it but the smell of natural gas was very strong in the store so I'm really thinking that exchanger has cracked bc they guy renting the store was being naive and ignoring it his helper a young woman claimed she was getting a headache so I'm guessing she is breathing carbon monoxide the local gas company came and turned the furnace off and said it was unsafe for the whole strip mall for their furnace to run ! The gas is on still but just turned the gv off. The blower motor belt was a little weak but with that strong odor of gas coming through I'm assuming a cracked heat exchanger

[@pheelmob]

All the fans are working and the pilot light I observed through a small sight glass and the flame had no blue in it from what I could see at first my attention was on the gv thinking it was bad and letting out too much WC PSI

[@ChristopherAshton]

Hi, I have a 100-3 which I don't know the history of. Perhaps it was replaced, perhaps not. I just did the blower motor (2nd time in 8 years) and didn't notice any popped metal bits down in the box. Looking at the flow of flame with the blower motor on, it seems the flames between the burners lap up towards the top of the box pretty regularly. Is that normal? They run higher than you show in your video there. (The flames going into the burner tubes don't rise up at all; it is only between the tubes where the flames rise). Thanks for your videos, this and others have been very very useful!

[@fredredd410]

any update on your furnace? mine does it too... wondering if I should change my heat exchanger or not. I have CO detectors but they all show 0ppm

[@kylebuehlman4207]

I have a old Armstrong furnace and I haven’t had any problems with it and this furnace has to be 13 or 14 years old now

[@grayfurnaceman]

Sounds good. GFM

[@danielpadlo2401]

Awesome Great Channel

[@grayfurnaceman]

Thanks for the support. GFM

[@thomasharmon7800]

Me and my neighbor put a Goodman furnace in one of my apartment buildings 8 years ago it's done the same thing cracked heat exchanger so I have two years left on warranty so I contact Goodman they tell me I have to have an invoice from the contractor put it in but it was me and my neighbor did installed it so they told me the warranty is void because me and my neighbor put it in bad Goodman

[@grayfurnaceman]

Unfortunately, typical. GFM

[@bshivanand1]

Continuation: Fired up furnace. Problem repeated. Called a HVAC technician. He opened cut open air handling unit to gain access to coils and cleaned them. He also changed the heat sensor underneath flame sensor. The problem has not gone away. Technician had to be away on family emergency. He has returned 2 days ago. Again he took a look at the furnace. He says he is not able to identify the problem. I opened up the unit and cleaned burners vacuumed heat exchanger tubes.

[@Rainmaker88]

No heat on this unit Bad ignitor Replaced Started up saw the middle burner doing this Condemned 1000+ co in exhaust

[@electriccar3253]

Sounds right to me. GFM

[@freewoodencrosses]

You should show the crack in the exchanger. It can be very small. Good advice though

[@grayfurnaceman]

These heat exchangers did not crack so much as the rivets pop loose and the 2 halves separate. GFM

[@glasser2819]

Goodman also makes "bottom of the barrel" AC Units... great source of opportunities... 😅

[@grayfurnaceman]

Take pics before. Be sure gas and electrical are off. GFM

[@brentmcgillis]

It has been my experience installing and repairing Goodman and in my opinion that the Goodman furnace is largely comprised of really cheap components throughout, and so I would not recommend this manufacturer to any person. It is not just the exchanger, it is everything, the Goodman is a service techs DREAM come true, because their furnaces are a money pit for consumers is my opinion. Installing these furnaces can only hurt your reputation is my conclusion. The only Good part of this product is in the name IMHO.

[@grayfurnaceman]

Yes, it does seem they look for cheap before anything else. GFM

[@Metalcastr]

Well no wonder, it's a Goodman.