Gas Furnace flame color & efficiency

Hi All,
With heating season starting in my area, I was changing the filter. Started the furnace to check the flame. Flame on all 3 burners are blue for about 1-1.5 inch, but above that they are yellow. Furnace is >20 years old Lenox.
Is there are efficiency problem with the flames as described above?
Thanks,
RichK
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RichK wrote:

1) Are you sure the flame tips are yellow, or are they orange?
2) If they are yellow, your likely not burning efficiently. Your primary air is lacking. This can cause sooting and heat exchanger impingment. A cool flame is not only inefficient, it's dangerous. Sooting causes the heat exchanger to become blocked and will inhibit the products of combustion from traveling out the flue.
You should call a professional who can observe, and make adjustments to your furance as needed.
--
Zyp



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Thanks Zyp,

You are right, they are closer to blue/orange. Also after a few minutes, they are becoming more blue.

That was my concern, but appears it's not as bad, as I initilly thought.

Have not been happy with local Pros. Several serviced this furnca and none has spotted the pilot set WAY high, which was costing me money. It was help from this group that guided me to adj it myslef.
I try get a feel for a problem, before I call for a bigger gun :-)
Regards,
RichK
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There is no way to tell without a combustion analyzer.
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RichK wrote:

A lot of times they will run an orange color if the furnace is dusty or there's dust in the air around it, as that's what color the dust seems to burn. Yellow color (like a candle or cigarette lighter) is the bad one, though if it's burning orange a lot of the time, it likely needs a cleaning..
--
Robert Hancock Saskatoon, SK, Canada
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Thanks Robert for a very nice and to the point explanation.
All the "advice" pages tell you to "get it adjusted" - well I did not mess with it, so it should not change by itself, assuming it was set right at one point. Cleaning of the burners is something it may need and I can do that myself.
Regards,
RichK
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