Furnace Repair - Lennox WhisperHeat G20

[@ron4274]

Absolutely one of the best tutorials that I have seen on KZbin - bravo!

[@kenh3037]

Thanks Maynard, you are a natural teacher. I wish the temperature sensor on this model was a little more accessible. Great job with your video!

[@MTMiser]

Thanks Ken. Yes, getting to the flame sensor is a real pain on this one!

[@JeffLaskowski]

Maynard: I appreciate the video. I had replaced the igniter and flame sensor but still did not light. After watching your video I took a similar Lennox Whisper furnace apart and cleaned out the tubes (which were pretty dingy looking). After watching you it made the job easier than I thought.

[@yutingred]

Maynard, thank you so much for the clear explanation, I followed your direction and resolved my furnace start up issues. Your video is one of the best I've seen.

[@MTMiser]

Thanks John. I'm glad it helped you out.

[@chris20sith]

thank you very much! I had to replace my flame sensor and these step by step instructions were really well done! this is the real purpose of youtube!!!

[@MTMiser]

Thanks chris20sith. Glad it helped you out.

[@meghangraham5988]

Fan control board replace segment helped us. Fan would not turn on in auto once furnace started. thank you!!

[@davidstackwell6347]

Yessss!!!!!!! Same furnace, same symptoms...replaced the flame sensor, still wouldn’t trigger the blower....replaced the fan switch board and wallah! Thanks for the share, saved me hundreds!

[@MTMiser]

That's great, David. I'm glad the video helped you.

[@MrEnwen]

How much does it cost for the blower control board? Thx

[@calvinyong8903]

Your video was very good and explained good. I love it. I had same problem and i need to change my control board. Now my furnace good for a year

[@jackqq4171]

thank you so much for the clear teaching!

[@BobWhite777]

Thanks for making this informative video. I have a 1992 Lennox Diplomat 78UGF3-75 which is very much like your furnace.

[@MTMiser]

You're welcome, bw 77. Hope it helped you.

[@heshmatfonouni1452]

It is very well done, I got the related answers, therefore, I thank Maynard the Miser for providing such an important information about heart of system in a a simple and understandable manner

[@sumw121__gaming5]

Your video on the whisper heat g20 was super helpful. Never worked on a furnance before, great detail

[@MTMiser]

Thanks sumw121. I hope it helped you.

[@matthewchapin600]

This video saved my cold butt! Thank you!!

[@escherfan9]

Great video! I'm troubleshooting my G20RQ3/4E-100-1 now and this video is a great place to start!

[@tttarms1970]

Did you fix it?

[@escherfan9]

I did, mine ended up being the capacitor but this video helped me to get to the root cause. Thanks again! Really appreciate the help, saved me a significant service bill.

[@alvinryan5022]

New borad does not match old one

[@cooldude2245]

Wow, you make it look easy

[@dwaynelowen256]

thanks for the information Maynard, working again. Nice to have heat on New Year's Eve

[@MTMiser]

You're welcome, Dwayne. Glad it was helpful to you. And I agree, it is nice to have heat on New Year's Eve! :-)

[@r.t.7925]

Great job. It looks like blower control was the only problem. Flame sensor can be cleaned with emery cloth - no need to replace.

[@MTMiser]

Thanks! Actually last year the blower control was probably the only thing wrong, but this fall it wouldn't even spark. I'd read several things about it possibly being the ignitor or the controller, so decided to just replace both of them (especially since both were very old and many recommended the Honeywell replacement controller). The flame sensor was included with the Honeywell so we decided to install that too since we had it on hand.

[@laylaogolf6451]

your video very helpful thank .

[@dhammer6869]

Basically same unit but I only had one blue wire and I put the white wire to the spark/sense and the IGN/ orange wire to the 7 plug and it worked.??

[@kongeng99]

Excellent video. I had a similar problem where the blower would not come on when the thermostat was set to 'auto'. Ended up replacing the circuit board. The bad circuit board's relay underside solder had melted.

[@MTMiser]

Thank you, Kong. Glad you got it fixed.

[@calvinyong8903]

I feel u when u say damn 😊

[@MTMiser]

Yeah, I was a little frustrated when it still wasn't working, lol.

[@cjc9719]

I believe the "extra" jet that came with your pilot assembly is actually an alternative/conversion jet that you would use for propane. It is part of the conversion kit used to convert this furnace to run on propane instead of natural gas.

[@MTMiser]

Probably so. Thanks CJ C.

[@NormandyFoye]

Thank you for this video. My unit is getting worse. I'll hear click, spark spark spark and then a final click and then nothing else happens. I leave the thermostat on auto and sometimes it will fire up just fine, but very rarely now. I suspect the main controller board might be the cause, which I will now replace with the Honeywell model you showed.

[@MTMiser]

Kurt - good luck with it. Could you tell that the clicks were coming from the main controller? It was pretty obvious on mine when I got up close to listen to it.

[@NormandyFoye]

Actually, I'm not sure after closer inspection. I'm starting to think its coming from the blower controller now because it has relays and the main controller doesn't, right? I'm just going to replace both parts and see where that leads me.

[@MTMiser]

I don't know what's inside that main controller other than electronics but it definitely can click. Mine was doing that when I wasn't getting a spark.

[@randgum9901]

I had exact same issue; inducer fan kicked on, damper door opened, slight click when call for gas, then pilot assembly igniter went click, click, clicked, but no flame. Replaced the gas valve and worked great.

[@aircooledtx]

That was good for DYI,repair. Hint, you will continue to have issues with your furnace , as your dryer is next to furnace. That model Lennox is also know to have serious heat exchanger problems. Suggest you think about upgrade of your furnace. The newer model do not have pilot . Lennox downflow furnaces are very efficient. since 2000.

[@MTMiser]

Thanks Michael. We could probably move the dryer to the other side of the washer. But why is it a problem? Is it because of venting? The furnace's intake from the house comes down from the ceiling into the top of the furnace, and the intake for the furnace's combustion comes from the front of the unit. The dryer's vent is about 9 feet laterally from the furnace.

[@aircooledtx]

Yes , lint goes into trap, but some still floats around also the dryer sheets chemical has effect of ignitor/flame sensor.

[@MTMiser]

Thanks for the info!

[@MarkSmith-hp6os]

How did you keep your burners in such good condition? My furnace is 26 years old and all the burners are badly corroded. Two service techs have visited. One said I have a bad pilot assembly. The other said the gas valve is bad.

[@MTMiser]

Just dumb luck I guess. We had never worked on the furnace before I did this video, but maybe a former owner did. Are you getting any flame from the pilot initially? What's the sequence of events? A bad flame sensor will prevent it from firing up the burners if it doesn't detect the pilot flame. If you can see a pilot flame but the burners never come on, that might be your issue. Take out the flame sensor and clean it up with some steel wool, then put it back in and try it. Be careful not to touch the metal probe part with your fingers as that could ruin it (it doesn't like the oils from your fingers).

[@CarlosMedinaPPS]

thanks for making this video. I have the same furnace.

[@MTMiser]

You're welcome, Carlos. I hope this can help you with any problems you might run into.

[@tomsheehan380]

Great video but...My Lennox g20 decided to not come on at the first cycle in the morning unless I turned the power switch off and on. It worked fine the rest of the day. I replaced the thermostat. Problem remained. I cleaned the flame sensor and it worked normally for 2 months then repeated the problem. I replaced the flame sensor but couldn't get the aluminum tubing back into the valve, so replaced the tubing and connector as well. Now the furnace hums to show power but nothing else happens.

[@MTMiser]

Tom, it's hard to troubleshoot these things without being there. I would probably try this: 1. Turn the thermostat off. 2. Turn the electrical breaker off, then back on again. 3. Stand in front of the furnace and have someone else turn the thermostat on, set to heat, making sure the temperature setting is at least a few degrees higher than the current ambient temperature. Then watch and listen to exactly what happens at the furnace. Does it just hum and nothing else? It should first open the damper door, then you should hear the ignitor clicking to ignite the pilot. The pilot should burn for awhile (maybe 20 to 30 seconds?) and then the main burners should ignite. The main burners should burn for maybe up to about a minute at which time the blower should turn on. Observe that and we'll go from there.

[@billbliss2500]

I'm trying to figure out on this Furnace how to install the Spring that goes to the Damper Door that makes and breaks the limit switch on the left side. In the video I saw where you took off the wires for the switch but Not how the spring was attached. Wondering if you could help.

[@MTMiser]

Watch the video starting at 23:15, which is where I start putting that spring back on.

[@tammytokash5314]

Great instruction for my EXACT furnace!! Thank you!! Can you tell me where to get the replacment wire for the flame sensor? The link provided seems to only include the sensor itself.

[@MTMiser]

Hi Tammy - I'm glad the video helped you. I didn't need to replace the wire in my unit, but they sell them at places like Amazon and Repair Clinic. Here's an Amazon link. Note, I will get a small commission from Amazon (at no cost to you) if you use this link. Thank you for your support and best of luck with your furnace. amzn.to/3gRKnwa

[@ricardocarrera5196]

We have the same problem...... But I'm not a certified technician can I still be able to purchase the part and install it my self?????

[@MTMiser]

I'm not a certified HVAC technician either. Had no trouble buying the parts. As far as installing them yourself, only you can answer that question, assuming your local ordinances don't make it illegal for you to DIY natural gas equipment.

[@krisrupchand1696]

The flame burner looks new, did you change them b4?

[@MTMiser]

No, but this was my girlfriend's house at the time and she had only owned it for 4 years, so not sure if someone else changed them earlier.

[@fuwangyang8060]

Thank you for the sharing. My home furnace is the same model as what you have. I turn my furnace off when going to bed every night. When the furnace is turned on every morning, it has big explosion when initial ignition. There is no more explosion during the day. What parts shall I change to get rid of the explosion?

[@MTMiser]

I wish I could tell you which part to replace but I'm not an expert at this. I did find this explanation though - see if it helps you: www.ragsdaleair.com/news/why-does-my-gas-furnace-come-on-with-a

[@fuwangyang8060]

Thank you for your sharing. Yes, I have been noticing the poblem of delayed ignition too. It now takes 13 seconds to ignite the pilot when initial ignition. Afterwards it takes 2 to 3 seconds only in the remaining of the day. Does Pilot & Ignitor Assembly get ageing problem or is it the problem of stack effect?

[@MTMiser]

@@fuwangyang8060 - I really don't know what "stack effect" is. And I can't say exactly what's happening with your furnace. You may have a dirty flame sensor and/or pilot assembly, or it could be a completely different problem altogether. One thing I would definitely do is mix up a solution of dish soap and water in a spray bottle and spray it on your gas connections to (and in) the furnace to make sure you don't have any gas leaks. Any leaks will show up as small bubbles. This problem could potentially be deadly so your best bet would be to call in a professional. Don't risk your life on this.

[@fuwangyang8060]

I appreciate your advice. I will take it.

[@tashacherry1480]

Ok soo Im a DIY kinda window and over the yrs have empressed myself lol. But please tell me at 9:55 NOT to bend annything and to just remove the line as he finally does AFTER bending the s*** out of those brackets (I hope it's not gonna be a problem later on ). But hey SOMEONE has to make the mistake first so I thank you sir, your video was EXTREMELY helpful and saved me a ton of money. Wait...could you of maybe just removed the pilot line and damper all as one piece? I ask because if you lose that spring you're in trouble and we've all had a spring get sprung at some point in life. Looks like you might be able to take out some screws on the inner furnace wall and undo some wires then remove the damper, control cover, ignition line, all together??? Or perhaps there's wires that need to be taken off first that you don't see unless you do it this way.

[@MTMiser]

Hi Tasha and thanks for your comment. Yeah, I should have removed that pilot line before trying to remove the manifold. But I was flying by the seat of my pants and didn't see it at first. Bending those tabs doesn't hurt anything as long as you don't have to do it a lot. No doubt it wouldn't take too many times before metal fatigue would break them off. Even if that happened, I don't know what damage it would do. I can't see any purpose for them even being there. As far as removing the damper as one piece, maybe that would be possible, I'm not sure. I didn't think I could get to all of the screws on that inner furnace wall with everything else in the way, but possibly by removing the metal cover below the damper it could be done with a long extension on a socket. Not sure. Why don't you try it and let us know? :-D Anyway, glad this saved you some money, I'm a big fan of that.

[@sanjaypahladsingh]

Thanks for making this awesome video. Currently I'm working on one. Damper door opens, pilot lights but doesn't light my burners. After few seconds pilot goes off and the blower comes on. Any idea what could be wrong?

[@jrlorance]

Clean the flame sensor or replace, they're cheap. It tells the burners whether or not they should light, so if the pilot has flame and the sensor is bad, the burners will think it's not okay to light

[@cjc9719]

I agree with Jacob, definitely sounds like a dirty flame sensor. Clean the stainless steel rod (sensor) part of it with super fine steel wool or green pad dish scrubber. Try not to use sandpaper or emery - if you scratch it up, it gets dirty faster and then needs to be cleaned more often.

[@teamAmerica101]

I know this may be a long shot as this was made some time ago but does this furnace have a summer setting mine does not blow cold air from the bacement even when set to cool?

[@MTMiser]

Brooks - I'm not sure what you mean by a "summer setting." There are high speed windings on the blower motor for use in summer when it's blowing air from the a/c unit. Maybe you have a problem with the blower control unit, which activates those high speed windings when the thermostat is set to "cool." I replaced that unit in the video, starting at 32:02 .

[@teamAmerica101]

@@MTMiser i was referring to the furnace just blowing air in the summer i dont have a ac unit but neither does my parents furnace but it blows cool air from their bacement in the summer just to clarify what i was referring to

[@spudhead523]

Yes it is possible to just have the blower on. Many thermostats have a switch to just allow the blower to come on, if you have A/C too and it is correctly wired to do so.

[@krisrupchand1696]

Hi. Where did you get the parts. By the way . Good video

[@MTMiser]

There's a list of parts with links at the bottom of the video's description.

[@drjahanzebamerica6922]

Where can I get all these parts ? I need to replace controller and gas valve

[@MTMiser]

Links to the parts that I replaced are in the video description - scroll to the bottom. Try RepairClinic.com to look up the gas valve part number and then shop around for best price.

[@debbielarry6824]

My husband and I have the exact unit described in this video. Just wanted to know where did you get the replacement parts for the unit?

[@MTMiser]

Hi Debbie - I just added links to the parts I replaced at the bottom of the description. I should have done that when I posted this originally - sorry. But anyway, here they are: Pilot Assembly (includes pilot jet, mounting bracket and ignitor as one unit): www.supplyhouse.com/sh/control/product/~product_id=18G90 Flame Sensor: www.supplyhouse.com/Lennox-52W29-Flame-Sensor-Kit-LB-74940A?gclid=EAIaIQobChMI1--hiMbf2QIVBksNCh2wLg44EAQYASABEgI6i_D_BwE Main Controller (this controller apparently replaces the Honeywell S8670K that I used): amazon.com/Replacement-Honeywell-Furnace-Integrated-Ignition/dp/B00E4267O8/ref=sr_1_5?keywords=honeywell+s8670k&qid=1573423254&sr=8-5 Blower Control Circuit Board: www.amazon.com/gp/product/B00XBSLQHE/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

[@spudhead523]

There was way too much disassembly just to get the pilot assy. out.Believe me, the last thing you want to mess with is the damper door assy. Turn off the power. You can then just remove the pilot line off the gas valve , disconnect the red H.V and white flame sensor wires off the ignitor module and GENTLY wiggle the pilot assy out. That will test your patience but it is very do-able. What I did to reinstall the pilot assy. is to gently bend and re-route that pilot gas tubing to come out between the middle and right ribbon burners and that will make the next removal very easy. Also, you can clean the flame sensor with a fine piece of steel wool. It is just a metal rod, it gets dirty and stops working and shuts down the furnace. There's nothing to go bad with it unless the ceramic insulator cracks.

[@bottledriver71]

My fan sometimes stays running on low fan after the furnace shuts off?

[@MTMiser]

It's normal for the fan to run for awhile before and after the burners light and turn off. Maybe a minute or two. If it keeps running beyond a few minutes, there's something wrong, but I couldn't say what the problem would be.

[@michaelh5532]

I have the same furnace. Last night I turned on the t-stat, it called for heat, went downstairs and the furnace just hums quietly. Does nothing else. Maybe the transformer?

[@MTMiser]

Sorry for not seeing this sooner. I hope you got it fixed. I don't know what that would be.

[@MTMiser]

For links to the parts I replaced in this video see the bottom of the video description.

[@justingibson8788]

These whisper heats are notorious for cracked heat exchangers.

[@autoguyk1]

My box said natural or LP, on the end of the extra one had a LP on it

[@nippon350z]

hello I would like to know where to get the parts to repair the furnace?? I need the Flame sensor and I do not know where to find it

[@MTMiser]

I got them from Amazon.com and Supplyhouse.com. If you have a Lennox this is probably the one you need, but you can call them to double check: www.supplyhouse.com/Lennox-52W29-Flame-Sensor-Kit-LB-74940A?gclid=EAIaIQobChMI1--hiMbf2QIVBksNCh2wLg44EAQYASABEgI6i_D_BwE

[@Rainmaker88]

That zone valve door is possibly the dumbest thing ever thought up in a furnace You did a great job though I have to hate on one thing and it's nothing you did, flexible gas lines are hideous.

[@MTMiser]

Thanks!

[@jonj3233]

I cant find the air filter on this model

[@MTMiser]

Ha ha! I had the same problem, Jon. Stickers on the inside of the furnace indicate how to find it but it just wasn't there. I finally figured out the only filter in the system was the one in the return inside the house. No filters at all in the furnace unit itself, at least in the one I have.

[@jonj3233]

I just moved in a one-story house with a crawl space and partial attic. My furnace is in the closet. I found mine about an hour after posting this because I've been getting sick since we moved here and thought that it could be from the filters needing to be changed. Mine are on top of the furnace where a massive ductwork comes out from the top of the furnace. One on right lays horizontal and one on left lays 45 degrees. Filter on left wasn't that dirty but one on right had mounds of dirt like it hasn't been changed in years! Probably wasn't because it's very hard to reach and wasn't discovered or was forgotten about. The ductwork goes into the attic but my vents for the rooms are on the floor. Now I'm wondering where my intake air is coming from- the crawl space or in the attic where there is probably fiberglass insulation!

[@MTMiser]

If it's like mine that big duct coming out of the top of the furnace leads to the return somewhere in the ceiling of the house, which should have a filter in it. The location of the vents you described sounds like the instructions on the sticker inside my furnace, but in mine they just aren't there.

[@roberttice4871]

So, he has a $300+ controller "on order", but the $15 flame sensor Should solve the problem.......and he's only changing it because he is waiting on the controller. Symptoms indicate the flame sensor is the issue.

[@MTMiser]

Thanks for your comment Robert. First, in 2017, when I did this work, the controller was about $115. Even today it is far below $300 at $177 on Amazon. Second, I replaced the flame sensor, and while I was in there, I figured I would also replace the pilot assembly and igniter because they looked dirty and I knew they were at least seven years old, but probably much older. Third, I replaced the main controller because I had read so many online accounts of that original one being a problem, and that the replacement one was much better. This resolved the problem of no spark, but although the burners would now light, the blower would not turn on and the whole unit shut down after a minute or so. So at that point I replaced the blower controller, and then it worked fine. So this was not a repair where I was troubleshooting to replace one defective part. I knew that no matter how many parts I replaced, it was still going to be far cheaper than calling an HVAC guy in there only to hear him tell me that the whole unit needed to be replaced, when I knew that wasn't the case. And the flame sensor, if it was a problem, wasn't the only problem. There were multiple problems, and I figured since I was in there I'd replace much of the inner workings so I wouldn't have to tear it apart again anytime soon. It's like doing a valve job on a car engine - while you're in there you replace seals, belts, maybe the water pump, etc. so you don't have to tear it apart again anytime soon. It's been over 6 years since I did this work and it's still working fine. I did have to clean the flame sensor about 3 years ago but that was the only issue in the past 6 years.

[@backbeatkeeper]

Why does a 110v furnace have a two pole breaker?

[@MTMiser]

Good question. I'm not an electrician so I don't know. Maybe the 240v comes in when the A/C is turned on. The same unit blows air for a/c. I'd bet that is the reason. The blower has low speed and high speed windings. The low speed is 120v for the furnace, high is for a/c. That's probably 240v.

[@backbeatkeeper]

If the 110v leg for the furnace is part of a 220v breaker then I'd be worried. In Calif. we have to have a separate breaker for the fau.

[@RICHIE_RICH89]

Lennox are terrible i had a trane xv95 best furnace ever solid stuff

[@alvinryan5022]

Boiler motor will not turn on

[@MTMiser]

Boiler? You mean the blower motor? If so, go to 31:40 in the video and see if that's the same thing that's happening to yours. If so, you may have a bad relay in the blower controller. Keep watching from there to see how to replace that controller.

[@spudhead523]

A poorly engineered furnace. Putting that blower controller next to that normally hot flue pipe doesn't make sense at all. No wonder many furnace techs dread working on these furnaces.

[@MTMiser]

And burying the pilot assembly in there wasn't smart either.

[@frankl6684]

You went ahead and replaced all those parts on that G20 and it shows clear signs of a bad heat exchanger. The tips of your burners are all blackened from the overheating from flame turbulence. In 25 years of service I have het to find one of these that weren’t cracked. The worst is that you had everything out of the way for you to see the cracks. On these furnaces they stand out like a sore thumb as the heat exchanger in galvanized and stays silver but the cracks show up as brown lines. You have no training so you don’t know where to look. You can get a snake camera and send up the heat exchanger at the back where it narrows in -the pass. This is where they ALL crack. That was a wast of time and parts dollars. Sorry

[@MTMiser]

Actually, it wasn't a waste of time and money at all. Quite the contrary - it saved us a lot of money that we might have spent on an entirely new unit. We've gotten over four more years of service out of this furnace, so far, than we would have otherwise. And it's still working fine. Truth is, if this furnace had serious cracks in the heat exchanger it would be setting off our CO alarms - which it hasn't. The blackening on the burners that you saw was likely due to them being filthy on the inside before I cleaned them all. A lot of crap came out of those burners when I had it apart. The furnace was installed about 23 years earlier and apparently had little maintenance from the former owners.

[@joelhill4107]

video will not play!!

[@MTMiser]

No problem here. Plays fine for me.