Janitrol- Wierd Burner Problem


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Old 10-27-09, 11:21 PM
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Janitrol- Wierd Burner Problem

Hello,
I have an old Goodman gas furnace, model GUN075-3, serial# 90109864, I'd tell you the year but Im not positive on if I could tell by the serial# or not.
The furnace hasn't been ran in over 4 years, I had some techs from an HVAC company come out several weeks ago and give a quick look at it to see if it was worthy or running or not. Without having gas running to it yet, they found that the only thing needed was the transformer replaced. No problem Im an electronic tech by trade.
After changing that I had a friend also a heating and cooling school grad come over and we pulled the burners out and gave them a quick cleaning along with the ignitor and replaced them. Fired it up for the first time, everything seemed to be working, pilot lit, burners lit, fans working.
The problem I'm having is that the last burner, after several minutes, the flame goes from looking good, to orangish and the flame starts to come toward the manifold slowly. After 10-15 trys we both arent sure whats causing this. Either a clogged orifice on the manifold or possibly an air leak. I wasnt sure of the proper way to clean the manifold orifice but I used a piece of wire to make sure it was clear. My father in law who had installed the furnace had used 2" PVC for the exaust now says I need 3" coming out of the furnace and thinks that might have something to do with the wandering flame.
Any help would be appreciated.
 
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Old 10-28-09, 12:07 AM
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My father-in-law mentioned to my wife that there was suposed to be a "baffle" as he called it somewhere above the burners that he hadn't reinstalled, that might have been thrown away by my wife accidently. Its too late tonight but Im not sure what this piece is since I didnt remove it, but he had said that it had to be put back on tho work correctly. Any clues on what that might be?
 
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Old 10-28-09, 03:32 PM
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I haven't got much of a responce. I can take a flame. Anything would be better than nothing at all. Come on lets here some feedback please.
 
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Old 10-28-09, 04:54 PM
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Baffle

In looking at the parts diagram of a GUN 075-3 I see a "flue restrictor" part #18248-01S but unless the furnace was disassembled it should be there. The restrictor is factory installed. From the serial # I think that furnace was made in 1990. The GUN series has a bad reputation for heat exchanger problems. I suggest you get your service people back to take a look at it.
 
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Old 10-28-09, 08:16 PM
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Is there somewhere I could find a diagram of this furnace not being a pro? The only thing Ive got is the schematic for it.
Thanks
 
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Old 10-29-09, 11:00 AM
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Anyone have a suggestion on where to find an actual diagram of my GUN075-3 furnace?
 
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Old 10-29-09, 04:11 PM
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Could a dirty or clogged orifice make that last burners flame wander? Ive haven't tried to fire it up since I cleaned the burner orifice.
 
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Old 10-29-09, 06:07 PM
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Since you say the flame on the far burner starts out good, but then after a short time starts getting orange and comes forward - does this occur right when the blower comes on? Or does it do it even before the blower comes on (Blower = the one that blows air through your registers). This is very important to know if this is happening or not, at that time, regarding the blower, so one can guess if primary heat exchanger is shot.
 
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Old 10-29-09, 06:18 PM
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Originally Posted by LEDDPIPE View Post
Could a dirty or clogged orifice make that last burners flame wander? Ive haven't tried to fire it up since I cleaned the burner orifice.
If that was the cause, you would think that it also would start out with bad flames, as well.

But in plumbing, that can happen, due to static pressure. A gas furnace though has none of that. There is no gas under pressure first sitting in the manifold, that could first cause good pressure and good flame, but then peter out as the static pressure went away and the lesser dynamic pressure trook over. That is why I (and Grady) am/are suspicious of the heat exchanger.

I really can't see a plugged baffle, secondary, vent or anything else either, - as that should affect all 3 burners the same way, more or less -at least I would think.

And I can't see spiders, a partially clogged orifice, etc., for that burner, causing it either. Because for the same reason, you'd think the flame would also start out bad.
 
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Old 10-29-09, 08:16 PM
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Bad flame on one burner

As ecman51 said, if that flame goes bad when the fan comes on, that's almost a dead give away the heat exchanger has failed. Given that furnace's reputation, I strongly urge you to have it checked by a professional. Failure to do so could cause carbon monoxide to leak into the house making you ill, or worse case, dead.
 
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Old 11-02-09, 10:16 PM
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I did not not mention one other thing I should have, intially, when I call for heat, the ignitor tries once or twice, the pilot lights, but take quite a bit of time for the burners to light, causing a "blow out" sorry lack of better term, I'm assuming the build of of gas, then all three burners are lit, blower is now on, burning what appears to be well for several minutes, then finally the last burners flame starts to do its dance and makes its way to the front until the furnace is shut off.
 
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Old 11-03-09, 04:22 PM
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Multiple Problems

With what you are saying, you could have multiple problems up to & including a bad heat exchanger. I strongly suggest calling a local professional to check out the furnace.
 
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Old 11-04-09, 11:26 AM
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When I had the HVAC techs come out a while back, they told me that one thing that needed to be done was a condenstion line of vent. I did that and after I got it running the first time there was alot of moisture exiting, like it should. My guess would be that since there wasnt a drain line on it before that all that moisture had to go somewhere, and probably made it to the heat exchanger. Just a guess.
Would there be any way to check or test the heat exchanger for leaks without tearing it out?
Same question would apply if I was to shop for another furnace, used, how would I check the heat exchanger without taking the furnace apart?
 
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Old 11-04-09, 01:44 PM
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Inspectin a heat exchanger is not a DIY task. You might spote a hole or corrosion problem, but it would be very eaqsy to overlook or miss such problems.

It's not the kind of job DIYers can do competently and reliably in most cases.
 
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Old 11-04-09, 06:28 PM
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Heat Exchanger Testing

Electronic combustion analysis can certainly point to a problem but the only way to know with certainty is to pull the heat exchanger. With the heat exchanger you have, cracks are common particularly near the crimp rings.
 
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Old 11-04-09, 06:43 PM
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Originally Posted by LEDDPIPE View Post
I did not not mention one other thing I should have, intially, when I call for heat, the ignitor tries once or twice, the pilot lights, but take quite a bit of time for the burners to light, causing a "blow out" sorry lack of better term, I'm assuming the build of of gas, then all three burners are lit, blower is now on, burning what appears to be well for several minutes, then finally the last burners flame starts to do its dance and makes its way to the front until the furnace is shut off.

Could you try to describe all these details better, and in a time frame also?

You say "blow out", yet all 3 burners light. if they oight, why say blow out". That is what I mean. We have to really try to "see" what you are seeing.

I'm trying to figure out if maybe there is just some cross over pipe issue going on, where that last burner is letting out lots of gas through it's orifice, but it can't jump from 1-2-3...-4 right. And then 4 ignites finally, with a bang....but not off of the crossover, but off the build up of gas at the burner....maybe. (Your "blow-out")

Also describe this creeping of the flame to the front. Are the flames themselves leaning towards the front of the furnace as opposed to pointing straight up? Is it acting as if you are holding a vacuum cleaner out in front of #4?

It sounds from your description that #4 starts acting up several minutes after the blower was already running? By blower do you mean the inducer blower? - or the blower that sends heat out your registers?

Besides what I have had said, I am also wondering if you could have a chunk out of the primary heat exchanger. I wish I could remember what brand furnace I diagnosed and visually found that very thing in some years back. I was able to spot that by looking up into the exchanger as good as I could without dismantling anything, and was able to see it missing directly above and to the side of the area where the flames came out of the far right burner.

And something wise for anyone with a fuel-burning appliance is to have one or more excellent quality CO and/or raw gas/CO detectors. They advise mounting them higher on the wall for quicker detection with natural gas.
 
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Old 11-04-09, 07:56 PM
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Originally Posted by ecman51` View Post
Could you try to describe all these details better, and in a time frame also?

You say "blow out", yet all 3 burners light. if they oight, why say blow out". That is what I mean. We have to really try to "see" what you are seeing.

I'm trying to figure out if maybe there is just some cross over pipe issue going on, where that last burner is letting out lots of gas through it's orifice, but it can't jump from 1-2-3...-4 right. And then 4 ignites finally, with a bang....but not off of the crossover, but off the build up of gas at the burner....maybe. (Your "blow-out")

Also describe this creeping of the flame to the front. Are the flames themselves leaning towards the front of the furnace as opposed to pointing straight up? Is it acting as if you are holding a vacuum cleaner out in front of #4?

It sounds from your description that #4 starts acting up several minutes after the blower was already running? By blower do you mean the inducer blower? - or the blower that sends heat out your registers?

Besides what I have had said, I am also wondering if you could have a chunk out of the primary heat exchanger. I wish I could remember what brand furnace I diagnosed and visually found that very thing in some years back. I was able to spot that by looking up into the exchanger as good as I could without dismantling anything, and was able to see it missing directly above and to the side of the area where the flames came out of the far right burner.

And something wise for anyone with a fuel-burning appliance is to have one or more excellent quality CO and/or raw gas/CO detectors. They advise mounting them higher on the wall for quicker detection with natural gas.
What I am calling a "blow out", is after the pilot is ignited, it takes a good minute or so for the burners to light, when the pilot finally lights the burners after a minute or so, and I am assuming the build up of gas fumes, then I get a good amount of fire or flame out to the front of the furnace where I might be standing. Then if I leave the furnace on, now all 3 burners are lit and look well. The "bang" is happening on the initial lighting of all 3 burners, not just one.
The creeping of the flame only happens on the 3rd burner, furthest from the gas valve. As far as "leaning", the flame looks straight up and down at first then actually starts leaning toward the front and appears to be spiraling as it comes forward. We have let it run until the flame from the 3rd burner is almost out to front compartment with the wiring etc.
"Blower", I am meaning the fan that blows heat through the registers.
 
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Old 11-04-09, 08:19 PM
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Well Im trying to get my HVAC tech friend back, he wants to tear everything apart to make sure there are no blockages. I was going to replace the unit anyways if the heat exchanger was bad.
The way it was originally set up,by the previous person who lived in the house was, with an old gravity furnace next to it, 3 ducts from the gravity furnace went directly to 3 vents, while another duct went from the gravity furnace to the plenum of the Goodman furnace next to it, then 3 more ducts went from the plenum to the last 3 vents in the house.
When I started doing the work on the Goodman, I installed new ductwork in the basement, getting the gravity furnace disconnected from the plenum.
While doing the duct work, I had found beer bottles and all sorts of junk in the ducts.(I was told that the prior person who lived hear had a drugged up girlfriend). This is why my tech buddy wants to tear it all apart to make sure its clear and cleaned.
 
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Old 11-04-09, 08:52 PM
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I have to check off for the night. Been on for hours tonight and haven't even had supper yet. Til tomorrow if all goes well. You have explained things better now for all those who may respond.
 
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Old 11-05-09, 06:46 PM
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Thanks for everyones comments, I apologize if my terminology has been off.
 
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Old 11-11-09, 04:01 PM
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Well I have fixed one of two problems, the actual burner ignition was fixed by adjusting the setting of the pilot. It light within a couple seconds after the pilot lights.
The second problem, the last burners flame working its way toward the front has not been fixed. I disconnected the panel holding a switch and mounts between the gas valve and the crossover pipe to the burners to get a better look of the burners as they were running.
My father-in-law swears the heat exchanger is fine, he still says the vent pipe is the source of the problem, so I called for heat with the vent pipe disconnected, pilot lights, fans on,burners lit, and I watch.
After a good 5 minutes the thing that really caught my attention was the flame coming out of the crossover pipe at the last burner all the way to the end of the crossover pipe where it is crimped. The burner itself didnt look bad, but it looked like the crossover pipe's flame was what was actually coming out the front, not bad color, blue, and slowly working its way frontwards. I did this about a dozen times with the same results and a headache.
 
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Old 11-11-09, 04:16 PM
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I didnt say in my last post, but the flame does start moving until the fan kicks on that blows air through the registers.
 
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Old 11-11-09, 04:35 PM
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Typo?

Originally Posted by LEDDPIPE View Post
I didnt say in my last post, but the flame does start moving until the fan kicks on that blows air through the registers.
Did you mean to say "the flame does NOT start moving ..."?

If that is the case, it's almost a dead giveaway of a bad heat exchanger.
 
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Old 11-11-09, 04:50 PM
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Sorry, I meant to say that the flame does not start to come forward until the fan kicks on.
 
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Old 11-11-09, 05:30 PM
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Heat Exchanger

I strongly urge you to call a local professional with electronic flue gas testing equipment & preferably one with a fiber optic heat exchanger inspection camera. From what you've told us, I believe you have a cracked heat exchanger. A defect in the heat exchanger can allow exhaust gases, including carbon monoxide, into the room air & your run of the mill CO detector is of little value until levels get beyond those which can cause serious harm to the elderly, infants, pregnant women, & others with underlying medical problems.
 
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Old 11-11-09, 05:42 PM
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I guess Im hoping I find another cause. I havent been using the furnace other than when I'm working on it.
 
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Old 11-11-09, 05:59 PM
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Another cause

It may be something else but there are certainly indications of a bad heat exchanger. When the pro looks at it please let us know what he/she finds.
Be sure he/she tests the exhaust gas with & without the fan on. If there is any change in the composition of the exhaust when the fan comes on particularly an increase in oxygen or decrease in CO (or CO2), it's certain there is leakage between the exhaust & room sides of the heat exchanger.
 
 

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