Rigid vs. Flex and draft

[rmcfall]

I've got a short masonry chimney (about 14 feet from stove flue exit) and have pretty much decided to go with a rigid liner. My reason for this is because my chimney is perfectly straight without any bends and because it isn't very tall. I've heard that rigid might provide better draft than flex because it is completely smooth. Given my chimney isn't very tall, I figured anything that would help the draft wouldn't hurt. Is it really true that rigid might provide better draft than flex? Or will I be wasting money by spending extra for the rigid? I'm looking at the Rhino Rigid. Thanks!

 

[Corie]

Absolutely. The inside of a flex liner is not a smooth surface- The smoother the surface exposed to the flow is, the lower the frictional losses to the surface are. Since you are on the short side, you'd be better suited to a rigid liner.


Plus, rigid liners can be make of thicker material.

 

[rmcfall]

Thanks. I'll just be burning wood so all I need is the 304 stainless. However, any reason it would be beneficial to go with the 316?

 

[Corie]

Absolutely again. Anything that builds up your chimney's resistance to corrosion is working in your favor, the way I see it. Although coal chimney deposits are significantly more corrosive it is important to note that wood fire creosote deposits are also corrosive.

Since a liner is not a fun nor cheap ordeal, the way I see it, it's best to go with the best liner you can afford. That said, if the 316 is cost prohibitive you do what you to do to make it work for you.

 

[rmcfall]

In terms of wrapping a rigid chimney in insulation and some sort of armor-flex, what's the best way to get something like that down a chimney? I imagine it isn't easy like the flex is...

Also, I read that nonfoil wrapped insulation is not used for insulating a liner and that to maintain a UL rating, foil wrapped insulation must be used. Is this true? What possible difference could the foil make?