Something you said needs clarified cjcaseih - The burners are the loudest when they ignite and are burning before the fan kicks on and you can really hear them ... It really sounds like the gas is burning freely inside the unit before the power vent gets a draw going but you can feel it sucking air? It should have 2 fans, one for exhaust and one for air movement. If I understand correctly you are saying the burners ignite before the exhaust fan turns on? Every power vented furnace I've been around has a purge cycle where the exhaust fan turns on a little while before the ignitor starts up or the burners ignite. The air fan is totally independent of the burner fan.But yes, a furnace drawing combustion air from the house will be noisier than one pulling it from outside and sealed.
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home heat machinery troubleshooting
