Table of Contents
Advertisement
Useindustry-approved standards t o sizeandinstall t he
supply andreturn airductsystem. Thiswillresult i na quiet
andlow-static s ystem thathasuniform airdistribution.
NOTE - Operation of this furnace in heating mode (indoor
blower operating at selected heating speed) with an exter-
nal static pressure which exceeds O.8 inches w.c. may re-
sult in erratic limit operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable
access panel should be installed in the supply air duct. The
access panel should be large enough to permit inspection
(by reflected light) of the heat exchanger for leaks after the
furnace is installed. If present, this access panel must al-
ways be in place when the furnace is operating and it must
not allow leaks into the supply air duct system.
Return Air Plenum
Return air must not be drawn from a room where this
furnace,
or any other gas appliance
(ie., a water heat-
er), is installed.
When return air is drawn from a room, a
negative pressure is created in the room. If a gas appliance
is operating in a room with negative pressure, the flue prod-
ucts can be pulled back down the vent pipe and into the
room. This reverse flow of the flue gas may result in incom-
plete combustion and the formation of carbon monoxide
gas. This toxic gas might then be distributed throughout the
house by the furnace duct system.
Return air can be brought in through the bottom or either
side of the furnace. If a furnace with bottom return air is
installed on a platform, make an airtight seal between the
bottom of the furnace and the platform to ensure that the
unit operates properly and safely. Use fiberglass sealing
strips, caulking, or equivalent sealing method between the
plenum and the furnace cabinet to ensure a tight seal. If a
filter is installed, size the return air duct to fit the filter frame.
All pipe, fittings, primer and solvent cement must conform
with American National Standard Institute and the Ameri-
can Society for Testing and Materials (ANSI/ASTM) stan-
dards. The solvent shall be free flowing and contain no
lumps, undissolved particles or any foreign matter that ad-
versely affects the joint strength or chemical resistance of
the cement. The cement shall show no gelation, stratifica-
tion, or separation that cannot be removed by stirring. Re-
fer to table 4 for approved piping and fitting materials.
TABLE 4
PIPING AND FITTINGS SPECIFICATIONS
ASTM
PIPE & FITTING MATERIAL
SPECIFICATION
Schedule 40 PVC (Pipe)
D1785
Schedule 40 PVC (Cellular Core Pipe)
F891
Schedule 40 PVC (Fittings)
D2466
Schedule 40 CPVC (Pipe)
F441
Schedule 40 CPVC (Fittings)
F438
SDR-21 PVC or SDR-26 PVC (Pipe)
D2241
SDR-21 CPVC or SDR-26 CPVC (Pipe)
F442
Schedule 40 ABS Cellular Core DWV (Pipe)
F628
Schedule 40 ABS (Pipe)
D1527
Schedule 40 ABS (Fittings)
D2468
ABS-DWV (Drain Waste & Vent)
D2661
(Pipe & Fittings)
PVC-DWV (Drain Waste & Vent)
D2665
Pipe & Fittings)
_ CAUTION
Use PVC solvent cement as specified in ASTM D2564 and
ABS solvent cement as specified in ASTM D2235. Primers
and solvents must meet ASTM specifications. PVC primer
is specified in ASTM F 656. As an alternate, use all purpose
cement, as specified in ASTM performance requirements
D-2564, D-2235 and F493 to bond ABS, PVC, or CPVC
pipe when using fittings and pipe made d the same materi-
als. Use transition solvent cement when bonding ABS to ei-
ther PVC or CPVC. Low temperature solvent cement is rec-
ommended. Metal or plastic strapping may be used for vent
pipe hangers.
Uniformly apply a liberal coat of PVC primer for PVC or use
a clean dry cloth for ABS to clean inside socket surface of
fitting and male end d pipe to depth of fitting socket. Refer
to the procedure specified in ASTM D3138.
Canadian Applications
Only - Pipe, fittings, primer and
solvent cement used to vent (exhaust) this appliance must
be certified
to ULC S636 and supplied
by a single
manufacturer as part of an approved vent (exhaust) sys-
tem. When bonding the vent system to the furnace, use
ULC $636 approved One-Step Transition Cement to bond
the pipe to the flue collar, or to bond the 90 ° elbow or re-
ducing 90 ° elbow to the flue collar. In addition, the first
three feet of vent pipe from the furnace flue collar must be
accessible for inspection.
Table 5 lists the available exhaust termination kits, as well
as vent pipe equivalencies which must be used when sizing
vent pipe. All Lennox vent terminations are PVC.
Page 13
Hide quick links:
Advertisement
Table of Contents
