Lennox Intermit. pilot

[kc-srvs]

Ok, first I will say hi to everyone being my first post.

Next, I received an emergency call today. When I got there and turned the power back on the furnace, Lennox - MD#G23Q2\3-75-2, the ID motor kicks on. Does the usual venting, then sends 24V to the pilot and ignitor, now here is where we get tricky... ignitor is sparking like a champ but the pilot won't lite. My first thought was no gas, not the case, I lite it with a Bic Stick. Furnace burners kick on and away she goes. So I go upstairs and turn the Stat down. Walk back down the stairs and of course the furnace is going through the normal shut down procedure. Instead of going upstairs again I jumper R + W, again the pilot won't light so I use the Bic. This time I pulled the flame sensor as I have narrowed the problem to the pilot igniting. The pilot lights up with the Bic and now I have an approx. 8" bright orange flame going to the middle HX opening... Now I'm lost... I was thinking maybe a crack in the HX because my thoughts were back to the basics of:

Blue flame = normal
Orange/yellow = Too much Oxygen
White = Not enough Oxygen

Then I had someone tell me that I have Orange and White mixed up! Can someone verify that and maybe shed some light on this damn pilot?? Oh, I replaced the gas valve just to be safe with one I had on the van and pilot does the same thing... Thanks for any input!

[pipefitter2005]

Is the pilot orfice and line cleen, I have seen on the g23 that the blue ignition control get week and did not put out enough spark to light the pilot. Replaced the ignition control and took care of problem. Also is the sensor ok.

[kc-srvs]

Pilot and orifice line is clean, I pulled and cleaned as I checked the spark. I am getting 30v on the ignition and the sensor works great. I'm just mind boggled on that darn 8" flame from the pilot.... It is being sucked into the HX by the Inducer motor... checked the amp draw and I get 1.0 on both lines motor reads 1.5 on the label...

[pipefitter2005]

The only way I could see a 8 inch pilot on a lennox g23 would be no orfice or wrong orfice in pilot or pilot adj on gas valve not set correct.

[hot wired]

does burner flame turn yellow when blower comes on.

[kc-srvs]

Just the middle one stays yellow... That is what led me to believe the middle HX was cracked... Then I get this other guy saying I have the colors from the basics mixed up:

Blue = Normal
Yellow/Orange = Too much Ox = crack in exchanger
White = Not enough Ox

I thought those above are the right combo, am I wrong? If I am then why the heck does a camp fire burn yellow/orange? Should burn white according to him.. lol. Regardless I say crack. Anyone else? Gonna open the plenum tomorrow morning...

[hot wired]

sounds like pilot valve on gas valve is having problems.cracked hx usually burner flame turns yellow or rollout occurs with cracked hx.

[pipefitter2005]

It sounds like there is more problems than a cracked heat exchanger. One way you could check to see if you have a crack on that furnace is pull the blower. That furnace has had problems with heat exchanger, it drops little rings in blower about the size of dime that is were they hold heat exchaner together and pops apart. also is the pilot 8 inches without indoor motor running.

[kc-srvs]

Originally posted by hot wired
sounds like pilot valve on gas valve is having problems.cracked hx usually burner flame turns yellow or rollout occurs with cracked hx.

New valve was installed, I checked the gas pressure = 3.5" W.C., and the flame is yellow/orange - 8" long - and it does roll. I just got thrown when another Tech reversed the colors on me... he is older and has, well thought had, more years in the field for exp. So he kinda made me second guess myself. Judging from the replies, I am right about the colors. And if I don't find a crack in that middle HX tomorrow I will definately be bamboozled! Never seen one like this before.

[kc-srvs]

Originally posted by pipefitter2005
It sounds like there is more problems than a cracked heat exchanger. One way you could check to see if you have a crack on that furnace is pull the blower. That furnace has had problems with heat exchanger, it drops little rings in blower about the size of dime that is were they hold heat exchaner together and pops apart. also is the pilot 8 inches without indoor motor running.

pilot is 8" with Inducer running only and same with blower running.

[pipefitter2005]

regardless of colors you should not have a 8 inch pilot and should not have to light it with bic lighter.

[kc-srvs]

*laughs

Yes, I know this. Just never seen it before and wondered if anyone else had. Also wondered about the color thing... kinda threw me for a loop when he said it was opposite. Thanks for the quick replies all! I think I will stick around and learn from some of the vet's.. and who know's might even pick something up from someone new to the job...

[MikeJ]

Is the sensor wire touching anything like the pilot tube? Are the spade connects good? Blue Johnson control? Nat gas or propane stamped on oriface?

[kc-srvs]

Blue Johson Control as you asked. Everything appears to be in order. Nat Gas for oriface...

[Edited by kc_srvs on 03-07-2005 at 09:01 AM]

[t527ed]

was pilot 8" long before new gas valve? sounds like pilot way out of adjusment or pilot orfice missing. get rid of
P O S johnson blue box install 53L90 kit.

[kc-srvs]

Was thinking of that, I know there have been a few updates since the install... heh, heh. Yes, the pilot did that when I went to adjust it from the original valve, I concluded the valve was bad... when I installed the new valve pilot did same thing and pilot adjustment doesn't make a diff. Going to test the incoming pressure as it still has that damn 1/2 psi regulator just before the gas valve. Wondering if that regulator isn't throwing things off... I know it can be eliminated.

[tinknocker service tech]

kc you changed the gas valve cleaned pilot the orfice is the right one and you have to lite the pilot by hand
the middle tube of hx is yellow flame and the pilot is still 8ins and yellow to.you pulled the blower and hx is good the inducer is working correctly. something is wrong with this picture. know if one tube is burning yelow with the blower off the tube is clodged or burner is clodged one or the other if the tube were you would have roll out and safety would trip.gas pressure does not sound like a problem cause the burners lite and work properly from what you have said. two gas valves doing the same thing not to common and the pilot burner you cleaned twice and made sure the orfice is correct. the sparker wont lite the pilot but a lighter will. ok now lets stop over thinking this and go back to the begining first thing is change the pilot burner it is defective if this is rely happening.
i have been a service teck for lonox since 82 and have never come across this on a g23. if nthe flame on the pilot is yelow and 8 inches long i cant see the flame get the proper flame recifacation to being on the burners and you sould have a biuld up of soot on the heat exchanger.
change the pilot burner with the correct one from lenox for the g23 and you should be fine

[MikeJ]

He's probably got the thing going now.
8" pilot flame would be rather large. Exaggeration? But still too big.

I jumper R + W, again the pilot won't light

I wonder what the voltage was at the gas valve? And also what the incoming gas pressure is? 2 things that should be checked with the symptoms he mentioned.

"Blue Johson Control as you asked"

Used to be if you saw them on a no heat= test them
Then it became= suspect them, they are intermittant
and then= Change them whenever you see them, working or not. About a hundred now or a hundred and emerg call later.

[gasman]

check the pilot orfice size. 8" pilot flame is too high. can you adjust pilot flame? also checked around inducer housing make sure it is sealed and not pulling pilot flame. I have experiece it where leakage around inducer will prevent pilot lighting.