Natural GAs Furnace Flame "Walking" on 1 Burner [Archive] - Chevelle Tech

: Natural GAs Furnace Flame "Walking" on 1 Burner

Feb 20th, 08, 10:57 PM
Hi folks. Must still be winter as we have a small problem with the nat gas furnace n the garage:(.

The unit starts and all 4 burners light and burn for a while. Then the flame on 4th burner (which is the one furthest from the gas valve) starts to retreat from its furthest end. It stays lit but is only burning 1/3-1/2 the length of the burner. All the others stay fully lit and are blue....

I suspect a dirty burner but would welcome your opinions/knowledge.

Feb 20th, 08, 11:34 PM
With a inspection mirror check burner for cracks or voids due to rot /corrosion / age. If burner looks ok visually top and bottom and no orifices appear plugged then it has to be a air/fuel mixture problem. That specific burner is burning lean and needs to be richer. Since you cannot control fuel rate of flow you control air into the burner plenum through a slideing air flow control on the service end of said burner. Should have a metal end cap with 2 or 3 openings in it. Should be able to twist this to adjust the size of the openings. smaller opening means less air into burner meaning more fuel. This has to be done with the furnace running and in a heat cycle. Be carefull not to get burnt or get the mixture too rich. Try and get the burner in question to burn like the others. Nice clean blue flame. Hope this helps. Maybe some of the HVAC people will swing by and give some expert advice. This is what I've learned over the years working on my own furnaces. I'm no expert, Just a DIY kinda guy on a budget.

Feb 20th, 08, 11:46 PM
Things that cause the flame to dance or lift or not burn at their proper place usually are -
1) dirty burner
2) stopped up heat exchanger
3) hole in heat exchanger

IF the flame tries to roll out of the combustion chamber or even rolls down it is most likely #2
1 & 2 both require removal of burner and cleaning while #3 means new furnace time.

See any difference if you stop the blower?
sometimes the flame will be blown away by the fan if there is a hole in the heat exchanger.

Feb 20th, 08, 11:55 PM
Hi Dean
I can see how to remove the burner and inspect. Other than a vacuum, how would you clean out a heat exchanger? There are no visible holes evident from a quick inspection and we cannot sense any CO with the sensor in the garage.

Feb 21st, 08, 12:35 AM
What type of furnace?
Cleaning out a stopped up heat exchanger requires taking EVERYTHING off including the flue pipe, flue draft diverter and flue baffles and scraping/vacuuming it out.

Feb 21st, 08, 8:36 AM
The item is an Olsen unit heter model KAS65H.

I watched it today and when the thermostst calls for heat the burners all light propperly. They stay lit until the blower comes on.
When the blower starts, the one burner starts to go out from furthest end then towards the gas manifiold. It remains lit for 1/3 of its length.

I'm thinking holed heat exchanger??? Air is entering the heat exchanger somewhere via the blower and pushing the flame out?????

Feb 21st, 08, 11:54 AM
That does sound like a hole in the heat exchanger. :(

Might be able to tare it all apart and weld it up.

Hi-po SS 454
Feb 21st, 08, 4:07 PM
One burner or more smothering or lifting can be caused by a restriction in firebox before it goes into vent.
BEST rerpair for firebox damage is replacement of Firebox or whole furnace

Feb 21st, 08, 10:48 PM
Quote tomorrow for a new unit heater:sad:

Oct 24th, 08, 10:39 PM
Found hole in 1 exchanger. Outer non pilot.

Can I disable that burner (outside 1 without the pilot) and run the unit heater on 3 burners/heat exchangers???

Oct 24th, 08, 11:24 PM
Yes, you could remove the orifice and put a plug in the manifold but why not just replace the heater.

Oct 25th, 08, 12:06 AM
Will replace the furnace soon.:thumbsup:
I'm just procrastinating. ;)
Darn things are $700.00 here :( and that presumes we install it ourselves:beers:.

Oct 26th, 08, 2:01 PM
Now I need a reference on which heater to buy??

I have 4 choices. Reznor, Modine, Lennox and Beacon Morris.
These are all 45000 BTU output units; 0 clearance ceiling mounts and I'll be using a vertical chimney.

Any suggestions or comments?????????

Nov 8th, 08, 10:01 PM
It's in. New Reznor:

Old Olsen and New Reznor :hurray:

Nov 9th, 08, 9:25 AM

Looks good and more head room too!!!

Reznor has been around forever, except now most units are made by 1 or 2 manufactures and everyone puts there name on it.