Lennox MERIT ML195UH Installation Instructions Manual page 14

Return air can be brought in through the bottom or either
side of the furnace (return air brought into either side of
furnace allowed in upflow applications only). 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 equiva-
lent 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
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 2 below for approved piping and fitting
materials.
IMPORTANT
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.
IMPORTANT
ML195UH 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.
Use PVC primer and solvent cement or ABS solvent ce-
ment meeting ASTM specifications, refer to Table 2. 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.
Low temperature solvent cement Low temperature solvent
cement is recommended during cooler weather. Metal or
plastic strapping may be used for vent pipe hangers. Uni-
formly 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.
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
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 manu-
facturer as part of an approved vent (exhaust) system. In
addition, the first three feet of vent pipe from the furnace
flue collar must be accessible for inspection.
Page 14
TABLE 2
D1785
F891
D2466
F441
F438
D2241
F442
F628
D1527
D2468
D2661
D2665
ASTM
SPECIFICATION
F656
D2564
F493
D2235
D2564, D2235,
F493
D3188
MARKING
ULCS636