New stove installation and new installer

[Mikelly]

I’m hoping someone sharper than I am can help me verify my plan for an upcoming wood stove installation. I keep reading but I’m getting confused. Please excuse the length of this post as I try to explain my situation.

The HiFlame Stallion rear venting stove will be on an interior wall using a horizontal through the wall stove pipe. It isn’t possible to go straight up BTW. Once through the wall it will go vertical through a vaulted ceiling to the outside. The room with the vaulted ceiling is a room addition and still under construction. It will have a wooden shiplap ceiling and a 4-12 roof pitch. The interior wall of the new room is the original exterior brick of my home.

I have ordered a Duraplus through the wall kit and framed the 14 ½” square opening in the soon to be non-combustible wall behind where the stove will go. I think I understand the rest of the installation but would value any input. It looks like I need to use the DuraPlus 6 in. Square Ceiling Support Box a storm collar and an adjustable flashing to get through the ceiling.

My assumptions and questions:

• I need to frame the sides of the 14 ½” square roof opening at an angle perpendicular to the floor…correct?
• I insert the support box in the framed hole then cut the sides on the top to match the roof line and fold them down to make the bottom parallel to the floor at least 2” below the ceiling…right?
• With the 14 ½” square opening framed and using the ceiling support box I do NOT need a close clearance box or a ventilated flashing. Is there an advantage to using a ventilated flashing anyway?
• I read that most of the heat comes from the stove itself but would it be beneficial to use single wall pipe inside the house to connect the stove to the wall thimble or is it safer to use double or triple wall?
• 
  
• Thanks in advance for any advise.

 

[DAKSY]

Sorry to tell you this, but the only place you MAY be able to use single wall pipe is directly BEHIND the stove.
From the wall pass thru, EVERYTHING to the cap will be Class A chimney. EVERYTHING.
You do NOT need a ceiling support box.
Where the Class A passes thru your ceiling, you need a ceiling firestop.
Above that, an insulation shield will be needed up to the underside of the roof sheathing.
Flashing on top of the roof, then a storm collar, MORE chimney & a cap.
INSIDE, wherever that Class A is exposed in a living area, it will need to be hidden within a Chase,
& that will make cleaning problematic, unless you also run your Class A DOWN into a room below
thru more firestops to a clean out cap. That will require a TEE after the initial wall pass thru.

 

[Mikelly]

Thanks for your response. What would be the advantage to using a firestop over a Ceiling Support Box. The cost is comparable. This is a vaulted (cathedral) ceiling.

The through the wall kit comes with the tee for clean out. I hadn’t planned on enclosing the vertical pipe on the other side of the wall unless it gets hot enough to be a safety issue. How hot will the outside of triple wall pipe get?

 

[DAKSY]

The ceiling support box isn't needed for your installation
& can't be used without modification, which isn't allowed by code.
Class A will not pass thru the opening at the bottom.
It is meant to be supported BY the box, where the connector pipe adapter is used.
The temperature of Class A gets hot enough that is must have a 2" MINIMUM clearance to combustibles.

 

[Mikelly]

I should have but I hadn't realized the Class A didn't attach directly to the ceiling support box. Guess I need to research firestops further. Thanks.