Ditch the double wall connector pipe for Kuuma?

[motoguy]

Our Vaporfire 100 is crated and ready for shipment. I'm extremely anxious to get it! We'll be replacing our existing Arbor Avalon wood stove with the Kuuma. Photos of the current setup can be seen here:

https://www.hearth.com/talk/threads...-kuuma-in-this-situation.139046/#post-1946989

The Avalon currently has double-walled pipe from the stove exit to the thimble. All the interior connector pipe is double walled. I really liked this, as it kept the pipe cool while it was "in the open", and accessible to the kids. I'll be walling off the area for the Kuuma, so access will be limited. I'll be adding an interior door, and an exterior door for a dedicated "furnace room". I'll no longer have bugs and wood chips across the carpet downstairs!

The Avalon exits vertically, while the Kuuma exits horizontally. I'm planning on replacing the current interior 90 with a pair of 45's. While searching for double-walled 45s to work with my Metalfab piping, I started seeing recommendations to use single-wall only connector pipe on the interior. This was based on discussion of barometric damper, manometer, etc. The Avalon has a traditional rotary damper, but the Kuuma will indeed have an electronic/barometric damper.

Do I just want to ditch the double wall interior connector pipe, and go with single wall? That will make things much simpler and less expensive, but I'd like to hear input from those "in the know" first.

 

[stee6043]

My two cents:

Single wall will eventually need to be replaced. Double wall should last a lot longer.
Double wall (assuming stainless) looks a lot cleaner
And last...the joints from single wall (in my experience) are more likely to leak during cold starts or weird weather days. Double wall is easy to seal with high temp RTV and collars and provides a fully sealed solution regardless of the unusual draft fluctuations that can occur.

I'd personally spend the money and go with the good stuff...

 

[motoguy]

My concern is really based less on cost, than on functionality. It seems that placing the barometric damper in double wall is an issue, as well as port for manometer, etc. Perhaps just put a single-walled T in the double-walled pipe run, to house the damper and manometer ports?

 

[FlightMedic32]

My daka exits horizontally, the Baro damper is the first piece and then the double wall. I looked at a single wall to double wall adapter piece and it was just a 3" piece that had he same exact connecting end as a normal double wall piece. No leaks, works wonderful.

 

[brenndatomu]

My concern is really based less on cost, than on functionality. It seems that placing the barometric damper in double wall is an issue, as well as port for manometer, etc. Perhaps just put a single-walled T in the double-walled pipe run, to house the damper and manometer ports?

That could work. You could always wrap some insulation blanket around the tee. Kuumas have pretty low exhaust temps, double wall is a good idea.

My daka exits horizontally, the Baro damper is the first piece and then the double wall

General rule of thumb is to leave space between the baro and the furnace connector. Can't remember the number...seems like it is a foot or 18" minimum

 

[FlightMedic32]

General rule of thumb is to leave space between the baro and the furnace connector. Can't remember the number...seems like it is a foot or 18" minimum[/QUOTE]

I had called the manufacturer to double check when I installed. The only thing recommended was 18" from another damper. Manual or internal. The daka has neither of those so...

I was getting a nice .05wc draft from the box in the 50mph wind yesterday and the Baro damper was dancing all around. Flue temps held at 400 right before the mason chimney

 

[STIHLY DAN]

No need at all for double wall unless its a clearance to combustibles thing.