Maximum length for outside air pipe?

[burnt03]

As the title says, is there a maximum run length for a 4" diameter outside air pipe?

Thanks!

 

[nate379]

For what?

 

[DanCorcoran]

"Run". Vertical or horizontal? Air intake or chimney?

 

[burnt03]

Sorry, wasn't very clear.

Air intake. I'm able to drop into the crawl space but have to run about 25'. I know there's a length limit on things like dryer vents and exhaust fans before it starts killing air flow. Just wondering if the same applies here.

 

[begreen]

Docs for most stoves are vague on this question, but I did find that Quadrafire says the oak length should not exceed the total flue length.

 

[Backwoods Savage]

I would not be afraid to try a 25' run. You might even go with a 6" if you don't get enough air flow.

 

[begreen]

No thoughts on reverse flow then eh?

 

[Backwoods Savage]

Could be a problem for sure but might be worth a try.

 

[begreen]

Not if that oak wants to become a flue.

 

[Backwoods Savage]

True sometimes but not always! Warm air will always want to travel up rather than down. I've seen this type of setup work, but only one time.

 

[tfdchief]

Not sure it is even applicable, but dryers can be no more than 25 ft.....subtract 5 ft for each 90 elbow.

 

[burnt03]

With the reverse flow you mentioned....

What happens? It starts drawing air down the chimney and the OAK tries to act as the flue??

Also, do I add the stovepipe length into total flue length?