Gas Furnace Not Heating Typical Lennox Problems

[@watwsplace8614]

Brother had the same issue for over a 2 years, new house. Tech was there countless times. Finally figured the gas pressure dropped when the hot water heater and stove came on. Gas company reluctantly changed regulator. No problems since.

[@HVACRSurvival]

I've had issues like that before👍👍

[@rolytech212]

Well, unless is Natural gas that you can’t change companies, change company. You need good service and if they can’t provide it, find someone that will.

[@natepeterson7145]

@HVACR Survival how come you don't start your own business, you definitely would be successful. All the equipment you know how to work on and not to mention all the equipment you've never worked on but still manage to get going. You and Chris are the best HVAC guys on KZbin IMO that makes regular content.

[@HVACRSurvival]

I was the HVAC service manager at my previous place of employer for 8 and 1/2 years, that taught me how the quoting system worked, warranty, dispatching, how budgets work, all the unexpected expenses that most people don't know about, and from what I've learned over the years is either you have to be a small one or two man operation or you need to have at least 15 employees, I learned real fast how hard it is to get work for the guys when we were slow in January through March, it didn't matter what the price was you just couldn't get the work, I also learned how hard it is to find good employees, you can't count on anybody but yourself. At my current location I am paid very well, I make on average 40 to 50,000 more dollars than what I did at my previous employer. That's not me bragging it's just saying that there's hardly any room to make that much more money on my own. The way I'm paid basically covers my expenses and I take the rest, that tells me what kind of money I would be making as a one-man operation. The biggest mistake most people make is they might know how to do the service side but they don't know how to do all the business side of things, then when you find a piece of equipment bad you have to install a new system. Which I'm pretty decent at installation but that's not what I enjoy doing. It's just not worth the extra hassle to make another $30,000-50k

[@fonzario]

On my Lennox furnace it turned out to be my gas valve. First the inducer motor came on. Pressure switch came on. Igniter came on. But then no flame. And I did measure 24 volts at the valve wires so I ordered a gas valve. Should arrive today. Will do an update after installation. Remove and replace. Turned on gas, checked for leaks. Fired it up and bingo! Even seems to put out better heat than before.

[@brnmcc01]

If those pressure switches don't go to at least 0.2 to 0.0 Ohms when closed, they can cause all kinds of issues and drive the board crazy. Same with thing Goodman ones, I've had a few pressure switches from Costa Rica on 4-5 year old furnaces from the 2016-2018 era that if the pressure switch has like around 1 Ohm resistance when closed, it won't throw a code, but the induced draft motor will short cycle, and won't ever get to the hot surface ignitor step. First time I ran into one doing that I was really scratching my head for awhile, and was going to replace the control board. But I had an idea, and I jumped out the pressure switch wires at the right moment, like 5 seconds after the draft motor got up to full speed. Ignitor came on, and it fired up and ran just fine, so the board was good. I checked the continuity of the switch when pulled closed, and it was reading from 0.5 to 0.8 Ohms. Enough to make a simple continuity tester beep, but not low enough for the board to work right. Replaced the pressure switch and all was fine. On closer inspection of the furnace, it looked like what was happening was there was a small water leak up on the roof, and during heavy rain, a little water would run down the flue pipe and then drip on top of the furnace cabinet and drip directly onto the pressure switch. So not only was it made in Costa Rica, but it got the Chinese Water Torture as well... Pressure switches don't like being damp...

[@HVACRSurvival]

Thanks for sharing thats a lot of good information!

[@jarodreebel6686]

I am working on the same furnace, exactly the same issue. You just solved it for me! I've got a few hours beating my head against the wall trying to figure it out. I've been fiddling with the vent because no codes! I could go on forever. Thanks you!!!

[@HVACRSurvival]

Awesome 🍺🍺🤜🤛👍👍

[@Ted_E_Bear]

Rick, you are so thorough with your work! I appreciate technicians who do that ! Thanks

[@leviramirez7873]

Got to love how they mount those Lennox flame sensors. Almost as bad as the carrier’s 😂. Good job Rick.

[@TheCallofdutymaster8]

Ratcheting 1/4” wrench, piece of cake getting those flame sensors out 👍

[@Freezier134a]

Definitely have to watch for moisture in the pressure switch too when the bleed hole where the hose pushes on plugs with lint, I see that a lot too.

[@HVACRSurvival]

Good points

[@throttlebottle5906]

pressure switches tend to rust up inside(spring/plate/contacts corrode) and get intermittent. I have diagnosed some that would work fine anywhere from ten to many hundreds of cycles, then suddenly not work and cause a lockout. by time you removed the cover and started checking it would start working again! one did it on and off for years. lol

[@HorsepowerHouse]

Flame Sensor replacement fixed my older Lennox system with similar symptoms. Not very difficult to do. I tried cleaning it, didn't solve it.

[@HVACRSurvival]

Nope. Cleaning would’ve worked just fine unless the porcelain was broke but I’m glad you got it.

[@Eddy63]

Another head scratcher but you fixed her up ... Thx as always ...

[@johnwalker890]

Good job Rick, That marker was sign to tell you , you're heating and cooling parts are coming from overseas.

[@HVACRSurvival]

🤣😁👍👍

[@hozerhvac4406]

Couple things on this one: 1. Service bulletin on those collector boxes. They are known for pressure ports being too small. New collector box comes with larger ports 2. On Lennox g43,g41 ,g51 and g61 pull blower crawl in and look back of secondary, you can look up to the primary where it meets the secondary and look for holes, very very common on these models. 3. Oddly enough lennox replaces Honeywell switches with Costa Rica on g43.41,61,51 series, however on there newer line up you would replace Costa Rica with Honeywell. Confusing I know Always always pull the blower on that line you will be suprised

[@HVACRSurvival]

Thanks for the info drop👍👍. I'm out of the Lennox loop now. I don't really miss working on them 😂. I do remember collector boxes having a few issues on some of the older g26s and some of the newer ones that came out after that, then I remember the PVC shavings blocking them ports. It was always some sort of excuse.

[@taylerellis378]

I just had a call on this same furnace last week same issue. I found that the gas pressure was too high. I adjusted the gas pressure 1st and second stage to manuf spec and issue was solved. The issue was when the gas entered the combustion chamber there was too much causing a slight explosion right at ignition which caused the pressure switches to trip out. Once all was adjusted it lit nice and smooth and no more issues. Like you I too went through everything and spent a good deal of time pin pointing the issue looking at everything. Like the unit in the video if it did light sucessfully with no trip it would run without fault. This issue only happened here and there when first lighting. Another thing I noticed on this lenoxx unit was how it gets rid of condensate most units have a drain on the bottom of the inducer draft housing this thing has it on the side which allows the housing to fill half way with condensate if the inducer does not flic it out and up into the drain tubing up where the ex pipe enters the inducer. Idk what the engineer was thinking when he designed this unit.

[@HVACRSurvival]

Several Lennox furnaces were like that, with drains attached to the draft motors but others didn't require it because they had enough slinging ability to get it out of the draft motor.

[@natew48]

With the g51, 61, and 71s, I found the best way to get to the flame sensor is to slide that rubber t coupler over and then use the 90°

[@HVACRSurvival]

I had a method but I forget what it was...lol

[@nathanhurst5155]

Nice video Rick. Was hoping to maybe see ya at the symposium this year but I’m sure like most of us work gets in the way for more things than we would like it to. 👍

[@HVACRSurvival]

@nat I wanted to but it didn't work out, I'm going to AHR Atlanta instead.

[@Infowarrior-45]

I had a stupid York giving pressure switch issues. It would never act up when I was there. Come to find out, there was a service bulletin, and York actually changed the pressure switch to one that would make at a lower pressure. Had I not called them after going 3 times to check a furnace that ran perfectly every time I showed up, I would have never known.

[@jrsmyth9761]

I pull that rubber tee, put a rag over the inducer opening and maybe the gas valve. This makes the flame sensor not to bad to access.

[@stevencossaboon3237]

Good job Rick. Hope you are doing well.

[@HVACRSurvival]

I can't complain 👍👍 thanks for asking! How about you?

[@thefathvacguy6341]

I hate the G51... Love to meet the engineer on that one

[@samuelg3586]

What your saying in the video reminds me of what my thoughts are during service calls hahaha. That's awesome. Good video brotha

[@HVACRSurvival]

I appreciate you taking the time to watch it and leaving a comment 👍👍🤜🤛

[@throttlebottle5906]

put the meter leads on the switch and tap it with screw driver handle. the resistance shouldn't change and it shouldn't open/bounce unless it's just barely being made by low too low of pressure. aka, use a bigger hammer or hammer side of any tool(lol), finger tapping often isn't quite enough.

[@jdub976]

Thank you. I have been staring at mine going why are they redundant. I never thought because you can orient it 2 ways. This has been a personal mental battle that has been driving me nuts lol

[@HVACRSurvival]

I'm glad I was able to help.

[@DOWNSBRI000]

I still have my G51MP, the gas valve is starting to go but otherwise runs great!

[@sjd3021]

to clean the flame sensor you can remove the intake plate below the burners and then stick you hand under the burners to the sensor

[@HVACRSurvival]

That would make it a little easier👍👍

[@jasonjohnsonHVAC]

Or you can remove the 4 screws on the top plate, remove the top cover of the combustion chamber and get to it from the top, it was a horrible design and i hate that rubber connector.

[@ronfigg5047]

On odd ones tripping like that have had cobwebs in the intake and get some moisture on them doesn't take much

[@tylerlaczko]

I'm having big issues with my g51mp-48c I have 2 of them and tested all the parts by swapping between the 2. Only things i didnt swap are the board, fan, fan box. Ignightor will not light up... Fan starts for 7 seconds then 1 green right light flashing. I ordered a new board but scared it might not fix.

[@HVACRSurvival]

What's the code translate to?

[@atomreynolds4618]

The problem is the name on the front!!

[@jochemsluis8834]

I have had problems with contacts which are poor for low voltages. they run straight copper vs silvered/gold for extra low voltage.

[@lindamorgan2678]

Hi this was a very interesting video and it kinda looks like mine with the combustion box cover and that darn Flame sensor and where the ignitor is situated I am having trouble with my Lennox G60UH -24A-045-2 . The motor will start and then in 20 minutes shut off. The codes are 3 alternating green fast flashes which they say is Ignitor, would that be a reliable thing to go by as it will not ignite if the pressure switch is not working. I am thinking the sequence to mine is induction motor pressure switch ignitor then the gas. Any fail down the line will shut off and not go to the next. Bought the new ignitor but how the heck do you get it out of there? two screws to remove the bracket were hard to do but there is NO room at all to get at that screw to take the ignitor off the bracket or even turn the bracket to get to the screw and the room below is shorter than the ignitor .. seems trapped at all directions does the combustion chambers need to be pulled out or something? Hope you can recall this crazy set up and help me out .. then again it could be the pressure switch not coding and just the ignitor instead because it did not come on? How you fella's work on these is amazing. If I could get someone like you I would just call but geez some of the techs are not that great I know from experience they just do not have detective minds it seems

[@oscalerup1129]

Gotta love the G51’s. We had a Lennox dealer that installed a lot of them. So I see plenty, they also liked gluing the intake to the box so when it came time to pull the burners it always sucked. Supposed to get cold next week here I’m sure I’ll see at least 1 Lennox 😉. you guys still have any G14 or G21 pulse furnaces kicking out there?

[@HVACRSurvival]

I used to see them more when I was with the Lennox dealer. I still say the best furnace ever made. 😎👍👍

[@jasonjohnsonHVAC]

Do you ever use the built in pump and test the switches independently of the system. I was taught you are allowed a 10% variance on the switch between the pressure it opens and its rating.

[@HVACRSurvival]

Sometimes, but not often, I usually use it for setting up an adjustable switches

[@jasonjohnsonHVAC]

@HVACR Survival that SDMN6 is a great tool. Had mine for 5 years niw and it still works great and has paid for itself many time over. Great video as always Rick

[@HVACRSurvival]

@@jasonjohnsonHVAC Thanks so much!

[@sprockkets]

Ha. My dumb furnace went from a 55 degree split to around 35. Incoming gas and out pressures are all in spec, but now it makes a high pitched whine when going into high stage. Thinking the valve has gone bad.

[@HVACRSurvival]

Clock the gas meter, verify fan operation, something changed here

[@sprockkets]

@@HVACRSurvival I checked that too. Gas meter actually confirmed my 50k/70k inputs (which checked out 2 years ago) are now around 35/47k input. Like you I checked heat output with Testo probes. I have a constant cfm motor in this unit. I had to set it to the lowest air flow setting to make sure it was at least 35, ugh. My gas water heater doesn't seem to have changed either. In my limited experience I've never seen a poor split on a furnace. When I tried upping the gas flow the high pitched whine became louder. I didn't feel right leaving it over spec. Flame looks fine too.

[@HVACRSurvival]

Where is the high pitch wine coming from? The blower motor or the draft motor

[@sprockkets]

@@HVACRSurvival It comes from the gas valve. I'm 100% on this - it happens when it goes into hi stage, and the noise gets worse if I turned up the gas flow for either low or high stage. The inducer motor has it's own wonderful whine that it makes. Lovely Goodman 96% furnace. Already as you said had to replace the hi pressure switch from costa rica.

[@sprockkets]

@@HVACRSurvival It's almost like a whistling noise, if that helps. I'm willing to post a video of it if that helps too.

[@zekenzy6486]

Great Video. Thank you for sharing

[@HVACRSurvival]

🤜🤛👍👍

[@sjd3021]

the furnace condensate trap doesnt look like its installed correctly....its supposed to be installed on the left outside of the furnace...but i can see why they did that..theres no room with the return duct in the way..this probably can cause problems with pressure switches

[@ryansoule416]

Also, why did you subtract 100 when you got a 183 reading on the return? Was you reading incorrect? If so why did you subtract 100. I am a bit confused there. Sorry I am learning.

[@HVACRSurvival]

Can you list the time where I said that so I can find it easier.

[@ryansoule416]

@@HVACRSurvival around the 13:25 mark, when you are doing temperature differential. Thanks a bunch for your other response to my comment on a separate topic as well. I appreciate it!

[@hvacmania8323]

Cracked heat exchanger?

[@victork3397]

Looks like the control board is junk too, not throwing any codes

[@HVACRSurvival]

Nope, it was doing it's job and lite the pilot. once it's lite it doesn't cycle the power to the large solenoid, that's being controlled but the thermostat.

[@tbelding]

It seems like the only way to get a "good" system is to simply have a reliable company install whatever they're willing to work on regularly. (The company we use has been in business for ..40 years? On the second owner, but the 'new' owner was a 15 year tech from the company, and hand picked.)

[@HVACRSurvival]

Good Installation practice is king👍👍

[@tbelding]

@@HVACRSurvival - I was thinking that the quality of the systems seem to be equally bad, no matter the manufacturer. So getting someone that installs it right, AND will maintain it properly, beats the brand name.

[@mrfrenzy.]

I work with different IT systems and only install equipment I know to be reliable. I rather say no to a job than to install cheaper stuff that is prone to giving problems.

[@HVACRSurvival]

I agree 100%, one happy customer might get you 2 or 3 other customers. One unsatisfied customer can cost you 10. Bad news travels faster than good.

[@tbelding]

@@mrfrenzy. I've spent almost 30 years as an IT consultant. My experience is that much of the equipment is unreliable no matter who makes it, or how expensive it is, and that sometimes the cheapest equipment is the most reliable.

[@97Napkins]

Por guy lol.. prob checked micro amps and found it was low and that it 😆

[@hangngoaigiare]

what's the minimum manifold pressure? Lennox can set below 2.8wc? not on a heil furnace. the minimum is 2.8 on heil. Inducer suction seem not stable better if number not jumping on manometer.

[@HVACRSurvival]

I'm not sure Lennox posted the min. I know the carrier does.

[@chrismargaris9257]

Good video. What is a better residential heating brand choice? I know the all have their own quirks, but one that is logically put together, easy to service, and offering some type of reliability. Keep up the great info you are sharing.

[@HVACRSurvival]

Carrier has some nice stuff. A quality install is key for less problems.

[@ralphlaurencastro]

How come on lennox when i test flame sensor the reading always jumps around?

[@HVACRSurvival]

It shouldn't jump around much. maybe .1 or .2 might depend on the brand of meter, it could also be meter probes are wearing out.

[@ryansoule416]

What does the higher resistance on the pressure switch indicate? I know it means its bad but what is making the resistance increase? your mouth pressure making the switch?

[@HVACRSurvival]

I was just making the switch open and close with my mouth, I was checking to see if the resistance would be different one time versus the next, in theory it should be the same every time, a good solid connection should be close to the same as what my leads were shorted together.

[@sterlingarcher46]

And there goes the Costa Rican fan base ... but you probably gained some more Mexican fans though so it's all good 😄

[@HVACRSurvival]

🙌😉

[@joeyf504327]

what was the final temp rise ? Higher speed help at all ?

[@HVACRSurvival]

I think it was two degrees cooler. I forget

[@texture6]

At 14:27 with the black and brown wire. Was that to change the fan speed or gas pressure. I was lost there. Thanks!

[@HVACRSurvival]

I was changing the fan speed, the air conditioner was at the highest speed possible while the heat was one step below it, so I switched them around. Gas pressure can only be changed in the gas valve on this furnace.

[@texture6]

Thank you sir, much appreciated

[@HVACRSurvival]

Your welcome!

[@brianmcdermott2430]

Time we'll spent.

[@HVACRSurvival]

I appreciate the feedback. Thanks for watching!

[@joehead1294]

Can you measure voltage drops across those switches or is the current so low that it makes it difficult to measure? Correction pens make good markers too.

[@HVACRSurvival]

Yes, that's what I was doing, it might help to have used my more accurate fluke 87V

[@joehead1294]

@@HVACRSurvival Sorry, missed that part. I see it now, 0.0vd. 👍

[@HVACRSurvival]

I'm starting to shoot in 4k so if you pinch in you'll see more detail on your phone.

[@joehead1294]

@@HVACRSurvival You're probably right about the 87. Unless it's a superconductor, anything carrying current should have some sort of drop across it. Don't know how low the 902 will go. I hear the Fieldpiece won't go very low, maybe Fluke you're using has a similar problem.

[@HVACRSurvival]

The clamp meter has never been known to be as precision as a bench meter

[@Boodieman72]

It always seems heating systems are more complicated to work on that air conditioning in your videos. I don't know if it is but it appears that way.

[@harrydickson4575]

👍👍👍

[@Slavelife9279]

That 2” pleated filter isn’t helping airflow either.

[@HVACRSurvival]

It actually wouldn't be any worse than an air bear filter. The 2"will give you a longer run time before becoming so dirty that it would cause an excessive pressure drop compared to a simple 1in fiberglass flat filter.

[@Trainspotter_Lux]

What did i have maked ??? 😂😂😂😂❤🎉

[@HVACRSurvival]

What's Maked?

[@auctionmusic]

Trane/American Standard

[@steveblake8766]

387 thumbs up

[@philipmariaegeanga7984]

chinese ones are much better they worked 0.001% at a time the rest is fail

[@marlonalmeida2474]

Lol

[@HVACRSurvival]

🤣👍👍

[@suzylarry1]

this is the sucky side of service work. Mr. Repaie guy is here looking at it and you look like a fool, Ya like I pay $85.00 and up for you to come visit , and no coffee or cookies , damn !

[@joeyysossa4144]

Whos the ROOKY??? YR NOT SUPPOSED TO USE scruff pad on the igniter...

[@HVACRSurvival]

scruff pad??? I use a stainless brush, it's perfect for flame sensors, it doesn't leave groves.