Reznor OH Unit Installation Manual - Manual (Page 12)

Form I-OH, PN 120390 R5, Page 12
140 and 190 use 8" diameter pipe; for Size 95, use 7" diameter pipe. Keep the length of
the vent pipe connection as short and direct as possible. As it leaves the heater, slope
the horizontal run upward at least one inch for each three feet of pipe. The horizontal
run should not be longer than one-half of the vertical or chimney height and never over
ten feet (3M) unless a draft inducer is being installed.
If the vent pipe connector passes through a combustible wall, it must be guarded at
the point of passage by either a metal ventilated thimble not less than 12" (305mm)
larger in diameter than the pipe, or a metal or burned fireclay thimble built in brickwork
or other approved fireproofing material extending not less than 8" (203mm) beyond all
sides of the thimble. If a thimble is not installed, all combustible material in the wall or
partition must be cut away 9" (229mm) from the pipe. If any material is used to close
this opening, it must be non-combustible.
Fasten all vent piping with sheetmetal screws and support horizontal vent pipe from
above with noncombustible straps. Avoid sharp turns in the vent pipe or other construc-
tion features that would create resistance to the flow of the flue gases. Do not use a
manually operated damper or any other device that will obstruct the free flow of the
flue gases.
The end of the vent pipe connection must not extend past the inside wall of the chim-
ney. A thimble may be used in the chimney connection to facilitate removal for cleaning.
The thimble should be permanently cemented in place with high-temperature cement.
Draft Regulator
Requirements
6. Mechanical
(cont'd)
6.2 Venting and
Combustion Air
(cont'd)
Loosen knob and
slide in slot to
change draft.
INCREASE
DECREASE
Option DB1,
Barometric
Draft
Regulator
FIGURE 11 - Draft
Regulator, Option
DB1 (Required in
Canada. Option
DB1 or equivalent
is required in U.S.)
6.2.1 Venting (cont'd)
Canadian Installation - Option DB1 certified barometric draft regulator is required and
must be installed near the heater flue outlet. The preferred mounting location for the
draft regulator is in the vertical flue pipe (See FIGURE 11). Depending on the venting
arrangement, the alternate location for installing the draft regulator is in the horizontal
run. Follow the manufacturer's instructions included with the draft regulator.
U.S.A. Installation - A UL listed type barometric draft regulator such as Option DB1,
must be installed (See Installation Note below for exception) in the flue near the heater
flue outlet. The preferred mounting location for the draft regulator is in the vertical flue
pipe (See FIGURE 5). Depending on the venting arrangement, the alternate location
for installing the draft regulator is in the horizontal run. Install the draft regulator accord-
ing to the manufacturer's instructions.
(INSTALLATION NOTE: Do not install a barometric draft regulator if the installation
includes an optional outside combustion air inlet, Option DE1.)
Optional Draft Inducer Relay (Option DH1)
A field-supplied U.L. (U.S.A.) or CSA/ULC (Canada) listed draft inducer is required
when the draft in the flue measures less than .04" w.c. on a draft gauge. Instructions
for measuring draft are included in Paragraph 8.2. A relay (Option DH1) is available for
connecting the draft inducer.
When a draft inducer is installed, a safety provision must be made to shut off the fuel
supply to the burner in the event of the failure of the draft inducer. See optional exhaust
flow safety switch on the wiring diagram.