Is a flue liner necessary?

[md_massimino]

I understand the role a flue liner plays in a residential fireplace chimney, but is it really necessary in an outdoor setting? I was thinking of just building a double wall chimney and capping it on the top with a piece of slate. Any advice?

[dmun]

That will work fine, it's just that a couple of lengths of 8" flue tile are MUCH cheaper than what you could build with firebrick.

[brickie in oz]

Originally Posted by dmun

That will work fine, it's just that a couple of lengths of 8" flue tile are MUCH cheaper than what you could build with firebrick.

You dont need firebricks for a chimney, most chimneys are built using normal bricks.

[Tscarborough]

You do not need firebrick, but if you are going by code, you need flue liner. It is faster and cheaper to use flue than to build a double wall chimney, anyway. For my BBQ pit chimney, I just built single wythe brick, but the heat going up an oven flue is much higher, plus all the joints will make creosote buildup an issue.

[Les]

Md's question had nothing to do with the type of brick - just a way to get it done. Dude, your approach to the vent will work. I would go with Davids suggestion of using a clay liner. They are inexpensive and readily available - worked for me.

[brickie in oz]

Originally Posted by Les

Md's question had nothing to with brick..

So now everyone has more knowledge.

[md_massimino]

OK, I'll stop bucking the system now Clay flue liner it is.

[Cheesesteak]

Originally Posted by dmun

That will work fine, it's just that a couple of lengths of 8" flue tile are MUCH cheaper than what you could build with firebrick.

Okay - I cannot get 8x8 square clay flue tile in may area. There's only 8" round clay flue tile - and the next smallest is 8x13 oval.

The 8" round is outside diameter - giving me an inside diameter of around 6".

Is that going to work?

I'd note that the 8" square clay flue liners from Superior are also outside dimensions . . .

thanks -
Dan

[Tscarborough]

Round is better, 8" round should be fine. The (very rough) rule of thumb is 10% of the opening is the size flue required. Bigger is generally better, espcially with square or rectangular flues. So if you have an 18"wX16"H opening (288 SqIn), then a flue in the neighborhood of 28-30 SqIn is good. A 6" flue gives you 28.27 SqIn, so it should work just fine.

[Cheesesteak]

Originally Posted by Tscarborough

Round is better, 8" round should be fine. The (very rough) rule of thumb is 10% of the opening is the size flue required. Bigger is generally better, espcially with square or rectangular flues. So if you have an 18"wX16"H opening (288 SqIn), then a flue in the neighborhood of 28-30 SqIn is good. A 6" flue gives you 28.27 SqIn, so it should work just fine.

My entry arch is 12" high, 19" wide. Here it is:



I figure I've got a 2.5" x 19" rectangle at the bottom of the arch, or 47.5 sq.in. and roughly 1/2 of a 9.5" radius circle, or 283.5 sq.in. / 2 = 141.75 sq.in. Total = 47.5 + 141.75 = 189.25 sq.in. opening in my entry arch. My 6" inside dia. clay flue is 28.27 sq.in which gives me a flue of approximately 15% of my oven opening. Sounds like that's more than sufficient . . .

Time to press on.