Smoker vent extension? MES 40

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Fire Starter
Original poster
Nov 8, 2010
Greer, SC
Folks, I saw a video where a guy put an extension on the top vent of his MES 40.  I have searched in here and can't find what I am looking for, so I figured I would ask.  What's the purpose of adding the extension?  He only had about 12 inches of extension, but said that it was suggested on this forum.  Why?
Its my understanding that when using the pit design calculations, to more easily achieve a draft thru the smoker that the height of the exhaust can be increased to equal increasing the exhaust diameter. Which is easier, increasing the stack height or cutting a bigger hole.

It seems to be justified in so much as those who have done the mailbox alts with the increased stack and the mailbox conversions don't seem to ever have any problems with their AMPS. Whereas those who go with just putting the AMPS in the smoker box can have troubles sometimes. <shrugs>

I like the mailbox conversion, the discharge extension, I dislike that I lose vent control and the ability to use chips to achieve it.

I use the AMPS in my box without the conversion. Most of the time AMPS works happily, Sometimes I have to use chips. Me, I blame gremlins. is reader supported and as an Amazon Associate, we may earn commissions from qualifying purchases.

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