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Fig 14
Fig 15
ROOF SUPPORTED INSTALLATIONS
There are two types of Roof Supported Installations: (1) Using a roof jack, and
(2) Using a Roof Support.
(1) For a roof jack installation, make sure that the square box portion of the
Support Box can extend at least 2" below the low side of the finished ceiling
(Fig 16). The roof jacket must remain level, and the top edge of the box must
cover the edge of the roof's decking material. Mobile home chimney
installations are roof supported. Do not seal openings in flashing.
1. Place Appliance: Place the appliance in its proper location, referring to the
manufacturer's instructions as to allowable distances from combustibles, etc.
2. Cut Openings: Cut a roof opening in your desired location, just as in a
Ceiling Supported Installation (Steps 1 through 5, page 4 – 6). If a separate
ceiling and roof exists, as shown in Figure 17 (Low Attic), first cut and frame a
ceiling opening as described in Ceiling-Supported Installations (Step 2). Refer
to Table 1 for clearance and framing specifications. If it is desired to install
through a cathedral ceiling (Fig 16), then the hole is cut in the roof.
3. Install Roof jack: Slip the roof jack into the framed opening so the square
portion projects at least 2 inches below the finished ceiling and rafters (bottom
of round portion is 5" below), and extends above the ceiling to framing or
decking materials that it can be nailed to. Level the roof jacket, and slit the
corners to the roofline where they extend beyond it. Using 8-penny nails, or 1-
1/2", #8 screws, per side (Fig 20). Screw the trim sections into the ceiling (Fig
6). Roof jack must extend from the roof line 6inches.
4. Complete Installation: Refer to Steps 7, 9 & 10 in the Ceiling Supported
Installation section to complete the Roof Supported installation.
(2) A Roof Support is used in installations where there is a cathedral ceiling,
and a Square Ceiling Support is not desired. The Roof Support allows the EV-
HST to come down into the room below the level of the ceiling (Fig 18). The
Roof Support can support a maximum of 45 feet of EVHST total, and
maximum of 20 feet below the support.
1. Cut and frame opening to provide a minimum 2" clearance on all sides of the
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