furnace burners - http://www.hvacmechanic.com/ Forums
Original message
| Edward
 |  "furnace burners"
, posted Thu 6 Nov 15:06  
I just looked at my furnace burners today and it appears that they are only burning about 1/2 to 2/3 of the way down the burner. In other words the last 1/3 or so of the holes in the burners towards the back of the furnace are not producing a flame.
Is something blocking these holes and is there a way to clean them out? My worst worry is that the burners need to be replaced. The furnace is about 14 years old.
thx,
Ed
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Replies:
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| Xenos
Webmaster 
| "Re(1):furnace burners" , posted Thu 6 Nov 17:47
Ed yes they could be in need of a cleaning however your description leads me to believe that the gas valve regulator spring may have lost it’s calibration. I recommend calling in a technician that will be able to adjust the gas pressure back to it’s proper setting.
Xenos.
The best way to escape a problem is to solve it.
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| | edward
| "Re(2):furnace burners" , posted Thu 6 Nov 19:36
Xenos,
Thx for your response. I guess what your saying is because all the burners are blocked equally that it is probably the pressure regulator. I had a technician here later today and he said that the burners needed replacement. Is he just trying to sell me something I do not need? He mentioned that the holes were all rusted and that he suspected that the metal had fatigued and filled the holes. I find it hard to believe that all the orifice holes fatigued the same in all 4 burners.
He also said that there was alot of soot that he needed to vacuum out and when looking I could also see it faintly on the floor to the side of the furnace. All the condensate drain was black in colour and he said it should be clear. Does any of this additional information change the situation?
Is it possible that the burners are clogged with soot and that's it?
I really need to get back to him tommorrow.
thx again for your help,
Ed
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| | Ad Mech
| "Re(3):furnace burners" , posted Thu 6 Nov 20:16
edward,
First of all, sharp observation about the burners not likely corroding at the same rate. It's possible, but it doesn't pass the initial 'smell test'.
What is the make and model of your furnace?
One possible cause is a blocked intake. Also, if 2" PVC is in use, 3" may have been a better choice... particularly if the venting run exceeds 30'. However, your pressure switch shouldn't accept an unsatisfactory condition in both cases.
Any normal service/clean should include pulling these burners, cleaning them and inspecting them. When was this last done?
Have you recently had the gas valve converted? Say from NG to LP? Not only is the outlet pressure important (and easily checked by a competent tech), but an improper conversion to LP could allow over-firing.
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| | edward
| "Re(4):furnace burners" , posted Thu 6 Nov 21:34
Ad Mech,
Thanks for the confirmation of my concern over all the burners being in the same condition.
The Furnace is and ICG Ultimate III Condensing Gas furnace model ICGH 100 100,000 BTUH input.
The intake is definitely not blocked as it is drawn from the top of the furnace via three 2" holes. The problem arises even with the front of the furnace off so at that point there is lots of combustion air.
As far as the venting for exhaust; I can't see why the size would affect it know since it has been working for 14 years at the installed size.
The guy who came did not pull the burners and inspect them nor try to clean them. I assume that should be the first step. I'm not sure when the last time this was done. The last regular maintenance I had done on it was probably 4 or 5 years ago. That would have been the last time and I don't recall the burners being pulled out then.
I've not had the gas valve converted.
thx for your help,
Ed
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| | Ad Mech
| "Re(5):furnace burners" , posted Thu 6 Nov 21:42
Ed
Not familiar with your brand of furnace bur condensing is condensing
Is this furnace inside the home and where does the combustion air come from? an intake grill? is it clean?
Taking off the door now to look for combustion is not relevent since clogged burners are existing.
Are these burners Long with slots in them? or are they short with round ends? Need more info
Dave
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| | edward
| "Re(6):furnace burners" , posted Thu 6 Nov 22:24:
The furnace is inside and the air is from the basement but there is a 4" intake line from outside for combustion.
I'm not suggesting to look for combustion I was just saying that when the door is off there is plenty of air as you were asking about blockage in the intake.
I'd say they are about 24" long with flared inlet. The flared inlet is about 2.5" dia going down to about 1.5" dia for the rest of the tube. They appear to have slots along the top of them.
One of my conerns is the soot. The technician said that there was a good amount inside. It was all over his hands. Looking now I can see small specs on the floor behing the furnace, in the dust on the furnace and small specs inside the furnace. Excuse my ignorance but where would all this soot come from? I understand it is from the improper combustion but where did the technician find all this soot (I was upstairs when this was vacuumed)? How does the soot get outside of the furnace? Wouldn't it just exit with the exhaust? Help me understand what is happening here?
thx again,
Ed
[this message was edited by edward on Thu 6 Nov 22:26] |
| | edward
| "Re(7):furnace burners" , posted Thu 6 Nov 22:29
Just some added questions on the soot. Could it be blocking the orifices at the far ends of the burners? If he vacuumed in there should that have cleared the soot from the orifices?
Ed
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| | Ad Mech
| "Re(8):furnace burners" , posted Thu 6 Nov 22:39
Soot!
on a condensing furnace there is a lot of moisture-soot is the incomplete burn of the gas-since the heat exchanger is moist the the soot collects on the heat exchanger-each time the unit runs more collects. it can fall down and block the ribbon burners-this is the type you have-checked your manufacturer-Keeptire-on their web site and this model is no longer listed-there should be a primary air adjustment for each burner tube but without a picture I can't tell you how to adjust it-Your heat exchanger(s) need to be cleaned -both primary and secondary-not an easy or clean task-find a reutable service company that doesn't mind getting dirty-usually the small locally owned company!
best of luck
Dave
Dave
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| | edward
| "Re(9):furnace burners" , posted Thu 6 Nov 22:49
Dave,
Thanks for all your help. I really appreciate it.
Ed
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| | edward
| "Re(8):furnace burners" , posted Thu 6 Nov 22:36
I also just noticed that, as the technician said, there is a bit of rust on the outlet of the burners. To me it looks like surface rust and really no major flaking.
Ad Mech,
Do you agree with Xenos that it possibly could just be the gas regulator setting that is preventing the gas from getting all the way to the last 1/3 of the burners.
After all this back and forth I still cannot see what is the cause for the poor combustion? Any ideas?
Thanks alot again for your help,
Ed
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| | Xenos
Webmaster
| "Re(9):furnace burners" , posted Fri 7 Nov 16:58
Ed are you actually telling us you had a licensed technician look at your furnace and didn’t clean anything or check the gas pressure. What are we missing here? What did you pay him to do. And how does he know the burners need replacing if he didn’t even take them out. Man he’s good.
Xenos.
The best way to escape a problem is to solve it.
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| | Edward
| "Re(10):furnace burners" , posted Fri 7 Nov 21:05
Xenos,
Yeah you are correct. I assumed he knew what he was talking about. I've used this company for years with my A/C and Heat recovery ventilator. Very professional and well priced; not the cheapest but not the most expensive. I trusted his judgement.
I talked to him today after some discussion with yourself and Dave last night. He basically said that because there was alot of soot that it was either the burners or the heat exchanger. They will inspect the heat exchanger when then pull out the burners. If the heat exchanger is gone then they say I might as well get a whole new furnace as the cost for the new heat ex. and it's installation plus a limit switch that I need replaced is about 2/3 the cost of a new furnace. The tech's feeling was since there was no soot in the house anywhere that it is most likely that the heat exchanger is not cracked but they will check it anyway once they get the furnace opened up.
Concerning the burners specifically, I looked more closely today without taking the burners out. They are all rusted along the openings from front to back. It appears that the rusting is a bit worse the farther back you go but it is hard to tell. I tried to slide a wire down the inside of the burner as far as I could and it went about 3/4 or the way down the tube and came out clean. Not sure if there is something in the burners that far down or the fact the the burners are much smaller at that point than the wire which was a solid 14 gauge wire.
All I can do at this point is take his word on it. I'll definitely keep the burners for further evaluation by someone else if they are replaced. The best that can occur is that when the burners are taken out that they are ok and just need to be cleaned. The cost of this would be the same as having someone else come and take them out and check them as well. I'll be sure to stay over him when he comes.
Any things I should look for that would indicate that the burners are gone or are not that I could use when the burners are removed.
The only thing I can think of is:
Excessive rust flaking would mean that I should replace them as trying to clean that and prevent it from continuing to happen would be more expensive I think than just putting in new ones. Does that make sense? I think this is what the techinician has told me is the problem: excessive rust flaking that block the orifices.
I guess if the tube when taken out is full of something like soot then that's obvious and as long as the orifices look ok then that should be fine. I could compare the orifices with the new orifices on the pieces he brings.
thanks for your help,
Ed
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| | Xenos
Webmaster
| "Re(2):Re(10):furnace burners" , posted Sat 8 Nov 06:53
Good Morning Ed. Yes the burners could need replacing. However as Ad Mech mentioned it would be extremely rare that they would all be operating the same. Something also caused all this soot could it be the burners YES however My experience leads me to believe it’s something else. Heat exchanger, Gas pressure, combustion air. I would suggest cleaning up the furnace and burners then fire the unit and check it all over. I wouldn’t recommend replacing the burners till you have ruled out what did cause the soot at this point it’s all speculation and the money spent on the new burners may be in vane. I am concerned about this rust on the burners, this a commonly a sign of a furnace under firing and starting to condense to early. Hence gas pressure.
P.S. Burners can usually be cleaned up pretty good with a wire brush on a drill. IF there holes are rotted bigger then they will need replacing.
Xenos.
The best way to escape a problem is to solve it.
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| | edward
| "Re(3):Re(10):furnace burners" , posted Tue 11 Nov 21:07
Xenos and Ad Tech:
The technician came today and the problem was the burners. I told him to check the pressure, both the primary and the secondary exchangers which he did. All was ok. The burners once removed were pretty beaten up. They were pretty rusted on the outside and all along the orifices. Not just smooth surface rust but pretty bubbly rough rust. There also was alot of soot in the the tubes. That was definitely in my mind blocking the holes in the last 1/4 or so of the burners. Air quality is fine. By process of elimination the burners had to be the cause of the soot. Everything else checked out ok.
Thanks guys for all your help,
Ed
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