Lennox Furnace won't light up

[eblend]

Originally posted by sputnik
What error codes are you getting (if any)?

It might also be that your condensate drain is plugged.

Only codes I ever see is the watchguard mode, which is when it fails to ignite 5 times in a row.

I really have no freaking clue anymore what is wrong, if it's going to be a new control board or something, I might as well just get a high efficiency furnace.

[jeffh]

New boards cost about $220. Some of this previous advice is not very good....it isnt your blower or the ignitor or even the condensate drain(cause you dont got one!! Haha). Good job on fixing your combustion air. The city should never have passed the gas inspection with that line so incredibly choked. Could have caused a co mishap. Why not call a tech at this point. Mid efficients are great.

[Crazyjoker77]

Originally posted by eblend


I got a recording going of the whole setup right now, hoping to catch the voltmeter when the flameout happens or when it doesn't ignite. Voltmeter is permanently hooked up right now to the gas valve and right in front of camera.

what ever happened to this video?

Have you actually checked the vent(exhaust not intake) outside?

[eblend]

Originally posted by Crazyjoker77


what ever happened to this video?

Have you actually checked the vent(exhaust not intake) outside?

The videos never caught anything, so I stopped pursuing, especially since i needed to get a better program to record, the build in windows 10 one only allows 3 hours of recording, and with my luck nothing ever stopped working during the multiple times i ran the video.

The exhaust vent is on the roof of the house since this is a mid efficiency furnace, and my house is pretty tall and with snow up there, not something I would want to do.

I have hopefully narrowed it down, we will see. When I came home today, I was more determined than ever to get this thing working, so my plan was to clean everything, reseat all connections, and tripple check stuff.

I have looked at the lower panel before, but never touched some of the wires, and noticed that two of the 5 or so nut connectors at the bottom, where thermostat and other wires plug in, were extremely loose, to the point where you can see them move in the socket. Maybe I wasn't getting a consistent connection on those terminals, and thus kicking out some mechanism. I have tightened all of those up. I have also crimped the flame sensor wire a little bit so it sits much snugger in it's place as I found it to be pretty loose compared to the other connections. I blew out all the dust from board, behind the board, and through the vaccume line to the pressure switch (on the inducer side). Hopefully something in there was my problem.

This morning I was set that this was a pressure switch problem, but after discovering those loose connections, it is my best feeling yet that I found the source of the problem, we will know in a few days how things go.

At this point, if it stops again, I am calling a tech. As was mentioned earlier in the thread, furnace is pretty simple I find, with lots of stuff I can do myself, so I wanted to make sure I exhaust all my avenues before I call in the pros.

[Maxt]

Intermittent issues are hard to troubleshoot without being there to see, hear and test everything in person.
I notice with some circuit boards, including lennox, that the safety device fault has to be there for XX seconds, before it will log the error as that device, sometimes faults happen so fast and remake that it just restarts the ignition sequence over and over and then logs as a flame failure instead.
On the lennox I did the other day, it was the air switch contacts not making good enough contact. It would make enough to start the sequence, but as soon as it had to energize the gas valve, the draw would make the contact break and it would restart. It would do it enough times to show up as flame failure and lock out. I was actually the second person to look at it, it was diagnosed by someone else first as a bad gas valve, because it logged the error code as flame failure.
Other things yours could be :
-Sticky gas valve
- could still be the ignitor, I've seen them with cracks that work intermittently
-bad circuit board, there is a code on the board for the board being bad, but I have never seen a board that actually sets the code condemning itself ( for those that believe in AI,, often you have to just add up the symptoms and what you see on your meters, and it leads to condemning the board.)
- Molex connector pin loose or corroded, this is weakness of lennox furnaces , sometimes the tang doesn't bite in the connector and the pins work out of the connector that goes onto the board.
-cracked porcelain on the flame sensor.
There are a bunch of other weird scenarios I've seen over the years , but those are the most common for that fault.
When its problems like that, I setup 2-3 meters on the furnace and watch it, flame signal, gas valve signal, safety circuit continuity and watch it through a few cycles.

[Maxt]

Originally posted by thetransporter
regardless of brand

these units are not designed to be trouble free, they are designed to earn the HVAC industry a return each year most of it unethical, this why many people prefer not to "upgrade" their low efficiency, furance from the 1960s

remove debris from all sensors
make sure flame sensor is good
make sure filter is clean
make sure igniter is lighting up properly, if not replace or clean, (if igniter is not working manually light the flame durring the GAS on session) end if
make sure inducer motor is ok and the vent is not clogged

diag codes can help as well.

Your hate is misplaced, the real culprit is the various energy efficiency pushed by different governments and their agencies. The Government demands something perform a certain efficiency by year XXXX and the industry has to punch out stuff in that time period. How do you long term test something that you don't have a long term to test? Its only as time goes by that they found that the random plastic piece breaks down over 4 years, or the velocity under 20% load wasn't enough to stop sooting in a heat exchanger when air return air was below 18 C, and crap like that. The expense of the parts can be blamed on the low Canadian dollar, most equipment is made in and for the US market.

[01RedDX]

.

[eblend]

Weird, all my fans kick on, well except for the big one, mainly because there is no flame.

So unfortunately still no further ahead, I felt confident I fixed it...I did not, died again today after 24 hours without issues.

Pulled out my washable filter and shoved in a fresh basic one....lets see if that helps. The washable one seems pretty dense compared to what I put in....blowing through it is even hard...fingers crossed...again.

Also going to setup the recording laptop again tonight...and concentrate more on the leds....guess before it goes into watchguard mode....they should be telling me what kicked off....didn't realize this, so going to get a new app and run it, hopefully no limit and it can record right up until the drive is full, which would be a long ass recording.

[OU812]

Been 3 days now. Fixed?

[suntan]

That or he's frozen to death.

[ZenOps]

My Lennox seems to get water buildup in the exhaust blower motor assembly every so often.

I do not get the icicles on the exhaust, so I'm assume that all that moisture that should be exhausting is falling back into the fan. The easy fix is to do a "burn" by running the furnace for 30 minutes instead of a normal 10 minute cycle on a warmer drier winter day. This should be done right away as soon as the furnace starts getting intermittent or else it might not turn on to be able to do the purge. Otherwise its a matter of opening it up, flicking the drainage tubes with the fingers, or taking the tubes off and giving er a good blow.

High efficiencies are definitely a lot finickier than good old reliable 60% effs.

[eblend]

No not fixed, I have just been flipping the switch every time it dies. I finally caught some video after resuming recording just last night. I can see that the furnace ignitor lights up, I can hear the click from the gas valve...and then no ignition. It does this 3 times, and then goes into watchguard mode. There is no status LEDs in between, just ignitor glow, gas valve click, and nothing. I am starting to think that it might just be the ignitor. Perhaps it isn't glowing strong enough to ignite. It's either that or the gas valve. If it clicks I presume it means it opens...and if it opens there is nothing in the way between gas and the ignitor...so it should ignite, but it isn't, so either it's clicking but not opening (I assume clicking noise is it opening..) or the ignitor isn't hot enough. I did see a post on some other forum about this where the light glows but not hot enough, so I think it's the most likely culprit. Unfortunately the igniter is like $100+, so would suck if it isn't it, but what can you do. Will poke some more around today but pretty sure that's my next course of action.

[craigcd]

Originally posted by eblend
No not fixed, I have just been flipping the switch every time it dies. I finally caught some video after resuming recording just last night. I can see that the furnace ignitor lights up, I can hear the click from the gas valve...and then no ignition. It does this 3 times, and then goes into watchguard mode. There is no status LEDs in between, just ignitor glow, gas valve click, and nothing. I am starting to think that it might just be the ignitor. Perhaps it isn't glowing strong enough to ignite. It's either that or the gas valve. If it clicks I presume it means it opens...and if it opens there is nothing in the way between gas and the ignitor...so it should ignite, but it isn't, so either it's clicking but not opening (I assume clicking noise is it opening..) or the ignitor isn't hot enough. I did see a post on some other forum about this where the light glows but not hot enough, so I think it's the most likely culprit. Unfortunately the igniter is like $100+, so would suck if it isn't it, but what can you do. Will poke some more around today but pretty sure that's my next course of action.

My father in law had the exact same problem on a similar furnace. It was the gas valve- the furnace is less than 24 months old..... couldnt believe it!

[jeffh]

Ya could be the gas valve. I just replaced mine on my 1.5year old house's hot water tank. Either way, if you replace the ignitor, keep the old one as a spare, as they are the one part of your furnace that are expected to need replacing before anything else.

[eblend]

Originally posted by craigcd


My father in law had the exact same problem on a similar furnace. It was the gas valve- the furnace is less than 24 months old..... couldnt believe it!

My buddy's friend lives in Evergreen pretty much on the same street, and from what he tells me, she had very similar issues as I am having, with many returns by furnace techs to try to troubleshoot it, at the end, it was a gas valve as well. I will review the videos tonight and take a look. I noticed yesterday as I was reviewing a 20+ hour video, which was mostly focused on the LED diag nights, when it ignited many times earlier...the glow from the furthest burner from the ignitor didn't show up for a few seconds after you can hear the noise of the burners....and at other times it was there right away as it ignited. I adjusted the camera to look at the flame from the top and will review tonight and see. Perhaps the gas valve is opening slowly...or not at all sometimes...will report back on what I find.

[eblend]

So further confirmation that I think it's the gas valve. Listened to the videos from last time it died, and the sound the valve makes the moment it fails is different than when it works.

When it works it's like a THUD...when it doesn't, it just a very quick, much more faint....Thug Thug in quick succession. I setup the video again with an external microphone sitting right against the gas valve, in tests it's a very definite sound, so going to run this and verify the sound. New valve is about $115 from armes but is about two weeks out, so will order one by end of week once I get confirmation.

[eblend]

Figured I would update you all in case anyone else has this problem.

It was the gas valve. I got the gas valve replaced (thank you Amre Supply) and now everything is working perfectly. $121 all in

[OU812]

1st post:
12-04-2016

Last Post
12-31-2016

You my friend are a patient guy. Glad its fixed (finally)

[Darell_n]

I hope you at least checked the manifold pressure with a new valve being installed.

[eblend]

Originally posted by OU812
1st post:
12-04-2016

Last Post
12-31-2016

You my friend are a patient guy. Glad its fixed (finally)

Haha. It wasn't so bad, it would run weeks at a time...then 3 days...and last few days before it completely pretty much gaving up it would run for an hour or so...then die. Luckily it was warm out. The valve was a special order so took 2 weeks to get. I didn't think it would degrade so quickly in the last few days. I had the valve installed on Thursday, wanted it to run a few days before declaring it a success.

Originally posted by Darell_n
I hope you at least checked the manifold pressure with a new valve being installed.

The valve is factory set to 3.5. My furnace manual says that for altitude of 0-4500 feet, it should be set to 3.5. Since Calgary is at ~3500, I don't think any adjustment is necessary. Do you think I should still get it checked? I don't mind having someone come out and check it, just figured the valve was factory set to what the furnace manual wants, so figured not required.