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Bryant furnace, yellow flame

Posted by plumberty (My Page) on
Sat, Feb 10, 07 at 13:39

I have been working on a Bryant 350MAV036080 L.P. furnace.
The problem is a bad smell and a all yellow flame. This is what I have done to it.

1. Checked propane pressure.
2. Cleaned heat exchanger.
3. New orifice.
4. New burners.
5. Intake & Exhaust lines are clear & within manufacture specs.
6. Co2 readings are 2000ppm and greater.
7. Pulled exhaust off of unit & this did not change the flame color or smell.
8. Pulled intake air pipe off & this did not change the flame color or smell.
9. Furnace shuts down on fault code 33. Spill over switch was reset.
10. I hooked my sweeper on the exhaust outside and the flame was normal and no smell.

What does this mean? Is the inducer motor not pushing the right amount? How do you check the inducer motor? I know it runs and is working but not sure if it is at full power. This furnace is 10yrs old.

What am I missing here?


Follow-Up Postings:

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RE: Bryant furnace, yellow flame

It's possible your flue passages are partially blocked and not creating a good enough draft. Yellow flame will cause sooting. Remove the burner again and use a light and a mirrow to inspect the flue passages way up near the top of the heat exchanger. The passages are pretty narrow so it doesn't take much. Also what was your gas pressure readings, did you check incoming and manifold pressure? I would also check the vanes on the inducer fan and make sure they are not plugged.


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RE: Bryant furnace, yellow flame

Hmmm...

The flame on my oil furnace is quite yellow. Is this a problem for oil, too ???

Marco


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RE: Bryant furnace, yellow flame

The pressure is fine. I will check the inducer vanes. I have already put a new burner in the unit. Has anyone had this experience with a partially clogged heat exchanger?


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RE: Bryant furnace, yellow flame

"Has anyone had this experience with a partially clogged heat exchanger?"
Yes, I've seen it quite often, that is why I suggested you check it.
Marco, no self respecting oil burner person here will tell you how to adjust your burner by eyeballing it. Those days are long gone. A Bachrach kit runs about 400 dollars though.


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RE: Bryant furnace, yellow flame

A yellow flame means not enough combustion air. It's either
not entering fast enough or not leaving fast enough. Burner openings too large, orifice too large or both.
Gas pressure too high,a 90 deg. elbow on the flue callor instead of a minimum 12" straight before the 90deg. more that 2 ninties on the venting system. A collapsed inner liner on the B vent. A cat litter box too close to the burner openings. Shall i go on ? Call in a
professional.
P.S. a yellow flame on an oil burner is almost normal. it
should be closer to a chrome color.


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RE: Bryant furnace, yellow flame

Vents should be taller that the ridgeline of the house. It the vent is near the bottom of the roof, then it needs to be tall on the outside. Astectics expect the vent to be less that 2 ft tall, but when the vent emerges lower on the roof, it needs to be tall enough to draft properly. At the same time, many problems can be explained with poor draft.

I had a Dry Cleaning customer, who was forced to replace his hot water heater every 2 years. It would rust and start leaking. I learned the draft probably caused the flues to soot up. I extended the flue pipe 3 feet taller, and the Hot water heater worked 4 years without problems. The manufacturer tried to blame the chemicals present in the cleaners, but the boiler did not have the same problems, and it was closer to the chemicals than the hot water heater. It kinda makes you wonder if anyone really knows the best way of anything.


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RE: Bryant furnace, yellow flame

Is it acceptable to clean a heat exchanger or flue pipe with an air hose? Seems it would do a good job getting them clean but may make a nes, especially with oil soot.


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RE: Bryant furnace, yellow flame

mr.hvac, I know you suggested that. I was just asking if anyone else besides you, have ran into this problem.

kalining, thanks for the advice. Sorry to bore you, no need for you to go on. I came hear seeking the experience of other professionals who may have experienced the same issue with the particular model/brand listed. FWIW, I am a professional but your attitude is not. Take off your cape and relax.


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RE: Bryant furnace, yellow flame

If you were a professional you wouldn't be on this site
asking these questions would you ? You would know why you
are having this problem. I'm sorry. I said it all wrong.
Yes you are a professional but you didn't say how many years in the buisness. Do you have 42 years in this racket ? My oil "F" licence is #387. there are two
million people in this province. They never retire a number
and never use the same number twice. I have experienced
your problem. I gave you the possible causes. That is what
you asked for, wasn't it? Minimum flue hight is 3 feet within 10 feet of the highest rize on a gas fired appliance
2 feet on a flat roof. We are hopefully all professionals here. If you need help, ask. We'll do our best. If you get an answer you don't like i might question your professionalizm. No offence. You asked. I answered. Sorry.


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RE: Bryant furnace, yellow flame

Posted by kalining on Sun, Feb 11, 07 at 12:52...

"P.S. a yellow flame on an oil burner is almost normal. it
should be closer to a chrome color."

That's what I got. Thanks, Kalining.

Marco


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RE: Bryant furnace, yellow flame

kalinging,
It must be nice knowing everything, unfortunately, I do not. I like to learn from others and their experience. Apparently, posting a question makes me not a professional then. Oh well.
I thought I could pose a question to others that may have experienced something like I am going thru. It did not occur to me that I needed to post my credentials, lic. # and people per capita to ask such a question. What's next? My dad is bigger than your dad?

I asked a question, to which you responded, in a condescending manner. The problem is not with your answer it's with your arrogance/attitude, "Shall I go on? Call in a professional". Try showing some respect in the future, people like to be treated that way.


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RE: Bryant furnace, yellow flame

Read my last post. " i'm sorry, no offence ". If you can't
read and spell my last name you might want to slow down a little. A professional can be 1 hour old just out of school
As i said before. you asked a question about your problem and i gave you many things that might cause this. if you think i know it all you have a problem. no one knows it all. what are you going to do if you have a customer that
refuses to allow you to change a nozzel on an oil burner
or filter because they say there is nothing wrong with it ?
you respect the customers wishes. I do. this post is closed
don't get me wrong. I'll help you. Just supply more info and think about thinking about taking advice or a suggestion. good luck


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RE: Bryant furnace, yellow flame

kalining,
Sorry for spelling your name wrong. The reason I posted was to get advice. I will listen to what other pros have to say, I just won't tolerate being belittled. Your first post stated options that had already been addressed if you would have slowed down and read my entire initial post.
3. New orifice.
4. New burners.
5. Intake & Exhaust lines are clear & within manufacture specs.
As far as the changing the nozzle on a oil burner part of your reply, I don't know where your going with that. If the customer doesn't want it, they don't get it.
I will post the fix when I check it out Monday. I have a feeling mr.hvac is right on this one.
Take care.


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RE: Bryant furnace, yellow flame

Posted by mr.havac on Sun, Feb 11, 07 at 12:43...

"Marco, no self respecting oil burner person here will tell you how to adjust your burner by eyeballing it. Those days are long gone. A Bachrach kit runs about 400 dollars though."

Oh no...my furnace was tuned by a pro not long after I installed it. I was only curious about the pale yellow flame I see through the sight glass when it's running. The title of this thread got me a little worried - somehow thought my flame should be blue. I was starting to (wrongly) second-guess the tech that did my furnace. I should have known better.

Paranoia will destroy ya'.

Marco


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RE: Bryant furnace, yellow flame

Shame on you Marco, just because the guy stopped for a dozen beers at the local naked girley bar before he came to your house you automatically assume he's incompetant!!! LOL
Didn't he leave a copy of the combustion efficiency test report with you? He should, if he pulled a test anyway. Find the copy and tell us his readings for Draft,CO, Smoke, and flue temp. That report is usually left near the heating appliance. Wait till tomorrow, I'm tired.


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RE: Bryant furnace, yellow flame

It was the secondary heat exchanger. Thanks for the advice.


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RE: Bryant furnace, yellow flame

Oh fer cryin out loud,,,, why didn't you just say it was a 90 plus in the first place???? Does everybody think that the techs that offer advice here know what every manufacturers model numbers mean? It would take one hell of an HVAC library to keep in their home to pull that off! Describe things folks, we don't mind trying to help but we're not walking spec sheets! The more you can supply the better your chances of getting your problem corrected.


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by the numbers

Hey mr.hvac! It wasn't the beers at the girlie-bar that got me worried. It was the empty (plastic) bottle of Douglas vodka I found in the burner compartment :-D

Here's what I got for numbers...

Flue Temp = 355 F
O = 9.1%
CO = 8.9%
CO = 0 ppm
Excess Air = 70.5%
Efficiency = 84.4%
Draft = 0.03 in HO
Smoke Spot = 0

Ambient Temp = 47.0 F
CO at Furnace = 0 ppm

Oil pressure = 140 psi

The flue temperature is low because I use the third fan speed (out of four) to eek a little more efficiency out of the system. The nice 4x14 registers disperse this much airflow without feeling drafty.

I thought the oil pressure was a bit high, as the manual recommends 130 psi. When I called the tech about it, he told me that 10 pounds will make little difference. I took him at his word (he does do this for a living, I don't).

My Spidey Sense now doubts that the oil pressure was verified. It wasn't written down anywhere. He sounded surprised when I asked, and rattled off the 140 psi figure from "memory". According to him, there was no need to adjust it because that's a normal pressure for Beckett burners.

The burner has a sticker that says "factory set at 130 psi". I'm gonna' guess that it is indeed set to that pressure (from the factory). The tech probably didn't check it, even after I had told him it was a DIY install.

I wasn't home when he did the tune up. He did say that the install looked good, and that very little adjustment was needed (cynical translation: butter me up for return business).

Please help me exorcise these demons of paranoia. Are the numbers - and the tech's explanations - good ones ?

Thanks,

Marco


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RE: Bryant furnace, yellow flame

I can't take credit for this one, I only leave bottles of MD 20/20 behind on service calls.


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RE: Bryant furnace, yellow flame

Sorry marco. I don't have my Bachrach Kit here right now and the efficiency calculator is in it. I'll tell you this though, that tech must have a computerized analyzer to get all those readings. I use an old fashioned kit which gives you draft, CO, smoke and flue temp and from these reading you figure efficiency. Your flue temp is pretty good, nice and low but when I set up a burner I try to get in the neighborhood of 11 minimum on the CO. 8.9 isn't bad but if he adjusted the air a little he probably could have gotten it higher with a trace smoke reading instead of zero. Most burner mfgs. recommend a trace of smoke. Not to worry, some burners get a little touchy and no matter what they just won't cooperate. Without my calculator I can't tell you how much improvement you'd get with a little tweaking of the air but it wouldn't be much. And NO don't try it by eyeballing, you'll probably only poops it up. :-0
"The flue temperature is low because I use the third fan speed (out of four) to eek a little more efficiency out of the system."
Could you explain your line of thought on that statement though please?


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RE: Bryant furnace, yellow flame

Thanks for the info, mr.hvac. You got it right all the way around. He used an analyser; it printed out those readings on a "cash register receipt. Before he adjusted the furnace, he said there was a "trace" of smoke. I guess it was personal preference on his part to make it zero. Crown specifies that the smoke spot should be 1 or less.

I still doubt that he checked the pump pressure. It's probably a moot point, as Beckett set it to 130 at the factory.

I cranked the blower to medium high to increase the thermal efficiency of the furnace. I figured that greater airflow over the heat exchanger would transfer more heat into my ducts - and less up the chimney. I know doing this lowered my heat rise across the heat exchanger. Yet the supply air still feels plenty warm. The oversized ductwork and registers disperse it nicely, as well.

I know that fan speed will have virtually no effect on combustion efficiency. That's all about the air/fuel mixture and proper atomisation of the fuel.

Thanks again for the help!

Peace.

Marco


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RE: Bryant furnace, yellow flame

I'd say you're in pretty good shape for the season heatingwise Marco. Now lets all hope we'll be retiring these oil burners early for the season this year.


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RE: Bryant furnace, yellow flame

Other considerations: Is there a fire burning in the fireplace (or other device)? Are there any exhaust fans running in the house? Is the house covered in ice or snow?
What happens when you open a door or window?


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