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All installations and services must be performed by qualified service personnel.
11
IV. INSTALLATION
A. ROOF JACK
The roof jack assembly and accessories must be listed by a nationally recognized testing agency
for the appropriate fuel.
The roof jack assembly must be installed according to the vent manufacturer’s instructions prior
to the furnace installation. (Refer to Figure 2 for flue location on furnace.) Adapters for pitched
roofs as well as extended barrel length roof jacks are available from other suppliers.
All vent seams and connections must be sealed with high temperature silicone caulk and/or high
temperature aluminum tape.
B. STANDARD CHIMNEY
When installed as a central furnace special type for single story dwelling, venting into a metal
vent system approved by a nationally recognized testing agency for the appropriate fuel type is
permitted. Lined masonry chimneys are acceptable when sized appropriately. The minimum
chimney size should equivalent to the inside free area of the 4-inch diameter vent collar exiting
the furnace, or 12.5 square inches.
Maximum chimney sizes and acceptable installation practices are referenced in the following
publications. In lieu of local codes, when installing the OMC-70 with fuel oil, refer to the latest
edition of the installation standard NFPA 31, Installation of Oil Burning Equipment. When
installing the GMC-85 with natural or LP gases, refer to Appendix G of the latest edition of the
installation standard NFPA 54, National Fuel Gas Code.
C. FURNACE LOCATION
1. For best performance, locate the furnace so that it is centralized with respect to the duct
system.
2. This furnace is only intended for installation with free air return through the furnace door
louvers. DO NOT connect a ducted return air system directly to the furnace. Improper
installation may create a fire hazard and damage internal equipment, as well as void all
manufacturer’s warranties.
3. This furnace may be installed on combustible flooring when utilizing either the No. 70
counterflow floor base, for below the floor duct systems, or with the cottage base, for floor
level air distribution. See Figures 1 for depictions of the No. 70 and the cottage bases.
4. This furnace is U.L. listed for closet, alcove or freestanding applications. All applications
must comply with the requirements of this manual.