I also have a 6220, I know that on the lower settings when only one fan is being called on to circulate air, that the other one still spins. It looks like it's running but it's not. After you light it, as it's coming up to temp on it's way to hr-5, you should be able to hear the second fan come on. Depending on you're settings, it's when it transitions from 2 to 3. You can press a display button on the side panel and you will get rf-1 or rf-2. (room fan) Soooooo, I guess what I would do, is fire it up, pull up a chair with your favorite beverage, listen for it to kick on the second fan, (remember the little dash will blink during transition) if it gets up to temp and you never heard the second fan kick on, press the display to make sure it called for it, if it did, pop the back panel and probe the fan terminals with a multi-meter, if both fans are showing 120ac but one of them isn't running under it's own power, you need a new fan. If you have verified that both fans are under power and operating normally, then it's time to look at restrictions in duct work or filter or something along those lines. I know on my furnace, it is no where near the air that is circulated when my lp furnace is running, but that has alot stronger fan than these twin 550's.

PS, do you have an isolation panel inside your fan compartment or are your fans exposed to the rest of the interior of the furnace? Do a search on here, if you don't have this, you will get soot throughout your house. Stupid design.

Just an observation from your pictures,You have a 12" hot air duct going out of the corn burner. max free flow air in a 12" duct would be 700cfm. with the elbows your only going to get about 500cfm.

Wouldn't his 12" duct be forced air unless he has no fans

lukecornstalker wrote:


hi luke, thanks for the reply. i was hoping that someone that owns a 6220 would help out. when i had the unit running on high pr-5 it was calling for both fans and they were both running. does the control board just send full power to the fans or can the control board determine how much power is sent to them? when i took the panel off the back i was wandering why the fans could draw air from the upper part of the 6220. did you make your own isolation panel or can it be bought? thanks for the help.

tfgrower wrote:


What I'm saying a straight piece of 12" duct will only flow 700cfm no matter how big of a fan is pushing air through it. John

Really, I wouldn't have guessed that, good information John. I just thought the more fan the more preasure the more air.

johnlb wrote:


hi john, the duct coming off the corn burner is 10 inch but i doubt that changes much. i was thinking that all the elbows would hurt the air flow a little. i have to have the elbows to clear the lid to the corn burner when it opens. do you think putting a duct booster fan in the 10" duct line would help?

I don't think you will gain by putting in a booster fan. the only way to increase the flow is to increase the plenum size.