DuraVent DuraPlus HTC - Manual (Page 8)

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members using the (6) 1-1/4” long, round
head wood screws provided (see Fig 6).
4. Frame Openings: Cut and frame
additional openings in each ceiling or floor
above the Support Box (Fig 7). Refer to Table
2 for dimensions. These openings are to hold
the Firestop Radiation Shield. Locate each
opening by using a laser level or dropping a
plumb bob to the four corners of the opening
below. If Elbows must be used to avoid
an obstruction, refer to the Offset Elbow
Installation section.
5. Cut Roof Opening: Cut an opening in
the roof directly above the opening below,
and at least 4 inches (100 mm) larger than
the chimney’s outside diameter to provide at
least a 2-inch (50 mm) clearance all around
the chimney. The chimney must be centered
within this opening and maintain the 2-inch
(50 mm) clearance to combustibles.
6. Install Firestop Radiation Shield:
A Firestop Radiation Shield is required
in multistory installations at each floor
penetration above the level at which
the Support Box is located. Example: in a
multistory home where the appliance is on
the ground floor (Support Box is in the 1st
floor ceiling), you would need a Firestop
Radiation Shield at the 2nd floor ceiling, and
at the 3rd floor ceiling, etc., including where
the chimney penetrates into the attic. Figure
7 shows a typical 2-story installation with
an attic. Note: a Firestop Radiation Shield is
not installed where the chimney penetrates
through the roof.
The Firestop Radiation Shield is in three parts:
the Firestop Plate, the Radiation Shield, and
the Collar (Fig 8). The plate portion of the
Firestop Radiation Shield is installed on the
underside of the ceiling/floor framing, with
the vertical flanges installed upward into
the framing. Use a minimum of either one
8 penny nail or one #8, 1-1/2” wood screws
per corner. The cylindrical “tube” portion of
the Firestop Radiation Shield is then installed
from the floor above, around the chimney
SqUARE CEILING
SUPPORT BOx
FOR FLAT OR
CATHEDRAL
CEILINGS
Figure 5
ROUND CEILING
SUPPORT
WITH TRIM
FOR FLAT CEILINGS
Box on opposite sides. Place the Guide Rails
on the Support Box at the proper height so
the bottom of the Support Box will be at the
correct distance from the ceiling (Fig 7A).
Secure the Guide Rails in place using 4 sheet
metal screws. IMPORTANT: the Guide Rails
are only used to help install the Support Box
level and are not used to help support the
weight of the chimney installation. Secure
the Support Box to the framing using at least
three (3) 8-penny nails per side (minimum
of 12 nails total), or a minimum of (3) #8,
1-1/2” wood screws. Adjust the overlapping
“U-shaped” Trim pieces so they cover the
Support Box, and secure them to the framing
(6) WOOD
SCREWS
(INCLUDED)
SqUARE CEILING
SUPPORT INSTALLED
WITH TRIM
MUST BE
3” (75mm)
MINIMUM
BELOW
CEILING ON
LOWER SIDE
(6) WOOD SCREWS
(INCLUDED)
Figure 6
ROUND CEILING SUPPORT
INSTALLED WITH TRIM