Model af-45. Why does it have some yellow flame?

Sorry I know nothing about the model - just wanted to say a yellow flame isn't right.
When a heater burns with a yellow flame it is inefficient, producing an excess of soot or carbon and producing an excess of carbon monoxide, a dangerous poisonous gas.

A blue flame is correct and efficient and ideally there should not even be yellow tips to the flame.

lack of air causing yellow flame burners need cleaning . Burners are blocked or injectors are .

If the flames are yellow AND lazy, not acting like the two blue flames are, the problem sounds like excess carbon build up within the heat exchanger ABOVE the two yellow burning burners. If that is the case, the yellow burning flames are contributing additionally to the carbon already in there. Eventually, the lazy flames will roll out into the furnace vistibule and possibly burn wiring creating a major problem. There are looooong wire handled bristle brushes 30" long that must be used to thoroughly clean the heat exchanger after the burners have been removed. A shop vac will help greatly in reducing the nasty carbon mess.

Usually, the vent collector hood and flue is removed to brush down from the top and up from the bottom alternately. If there are air shutters on the burners, make sure they haven't been throttled too far down limiting the combustion air causing the original problem.

You need a certified HVAC service tech to look at this issue.

If your grill is older and has seen several seasons check for obstructions elsewhere the venturi is only one place for problems, check for hose kinks loose connections. If this is in a cold weather area, it maybe just low pressure. Also look for collected/ponded water in the burner tubes, especially if the flames are yellow.

first clean the burners and check injectors are clean yellow flame is lack of air to burners , check pressure is not too high IE right pressure to burn .

If your furnace lights and the gas stays on for 8 to 10 seconds, then shuts right back off, then you need to clean your flame sensor with light sand paper or steel wool. You might need a new flame sensor, but most of the time they can be cleaned an will work well after cleaning.

The pilot has a thermocouple attached to it. Clean this with some sand paper. Then relite. At the pilot tap with screw driver and you should see the flame turn yellow then blue (pilot flame). This will heat the t'couple hotter then the burners should light. If not replace gas valve.

yellow flames indicates blocked gas jets... must be cleaned or replaced before using for safety reasons

HI
I know this stinks but if the ents to the motor are clean you need your motor rebuilt. There are probably many people in your area who can do this look in yellow pages for electric motor rebuilding, alternator, starter

A <i>temporary</i> orange flame from your gas stove can also occur at peak usage times. An increase in local demand can cause a decrease in pressure in the natural gas line. If all of your gas appliances are in combustion simultaneously, this may also cause a drop in pressure, especially in older houses. If the problem persists, it is likely a dirty/clogged burner or the stove needs servicing. In general, an orange flame (on a gas combustion appliance) means incomplete combustion and carbon monoxide production.

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