Pipe Fittings Specifications - Lennox MERIT Series Installation Instructions Manual

Duct Installation
Down-Flow Unit
FIGURE 19
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 products can be
pulled back down the vent pipe and into the room. This
reverse flow of the flue gas may result in incomplete com-
bustion and the formation of carbon monwoxide gas.
This raw gas or toxic fumes might then be distributed
throughout the house by the furnace duct system.
Use fiberglass sealing strips, caulking, or equivalent seal-
ing 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.
Pipe & Fittings Specifications
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
adversely affects the joint strength or chemical resistance
of the cement. The cement shall show no gelation, strati-
fication, or separation that cannot be removed by stirring.
Refer to the table 4 below for approved piping and fitting
materials.
CAUTION
Solvent cements for plastic pipe are flammable liquids
and should be kept away from all sources of ignition.
Do not use excessive amounts of solvent cement when
making joints. Good ventilation should be maintained to
reduce fire hazard and to minimize breathing of solvent
vapors. Avoid contact of cement with skin and eyes.
Use PVC primer and solvent cement or ABS solvent ce-
ment meeting ASTM specifications, refer to Table 4. As an
alternate, use all purpose cement, to bond ABS, PVC, or
CPVC pipe when using fittings and pipe made of the same
materials. Use transition solvent cement when bonding
ABS to either PVC or CPVC.
SUPPLY
AIR
PIPING AND FITTINGS SPECIFICATIONS
Schedule 40 PVC (Pipe)
Schedule 40 PVC (Cellular Core Pipe)
Schedule 40 PVC (Fittings)
Schedule 40 CPVC (Pipe)
Schedule 40 CPVC (Fittings)
SDR-21 PVC or SDR-26 PVC (Pipe)
SDR-21 CPVC or SDR-26 CPVC (Pipe)
Schedule 40 ABS Cellular Core DWV
(Pipe)
Schedule 40 ABS (Pipe)
Schedule 40 ABS (Fittings)
ABS-DWV (Drain Waste & Vent) (Pipe &
Fittings)
PVC-DWV (Drain Waste & Vent) Pipe &
Fittings)
PRIMER & SOLVENT CEMENT
PVC & CPVC Primer
PVC Solvent Cement
CPVC Solvent Cement
ABS Solvent Cement
PVC/CPVC/ABS All Purpose Cement
For Fittings & Pipe of the same material
ABS to PVC or CPVC Transition Solvent
Cement
CANADA PIPE & FITTING & SOLVENT
CEMENT
PVC & CPVC Pipe and Fittings
PVC & CPVC Solvent Cement
ABS to PVC or CPVC Transition
Cement
POLYPROPYLENE VENTING SYSTEM
PolyPro® by Duravent
InnoFlue® by Centrotherm
ML195DF exhaust and intake connections are made
of PVC. Use PVC primer and solvent cement when
using PVC vent pipe. When using ABS vent pipe, use
transitional solvent cement to make connections to the
PVC fittings in the unit.
Low temperature solvent cement is recommended during
cooler weather. 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 of pipe to
depth of fitting socket.
Page 12
TABLE 4
SPECIFICATION
D2564, D2235,
IMPORTANT
D1785
F891
D2466
F441
F438
D2241
F442
F628
D1527
D2468
D2661
D2665
ASTM
F656
D2564
F493
D2235
F493
D3188
MARKING
ULCS636