Installation and Maintenance Manual

Installation: Piping
36 GTND-SVX01B-EN
Install thimble if required by local codes or type of wall
construction. Concentric vent box may be fastened
directly to wall or spaced away from wall using suitable
brackets (field supplied). Cut a length of pipe so that it will
protrude 4 inches (102 mm) through the wall when the box
is mounted in position. Fasten pipe to box with sheet metal
screws, using at least three screws per joint. Seal joint with
silicone sealant. Insert pipe through wall and fasten
adapter box in place so that the pipe pitches downward 1/
4 inch per foot (21 mm/m) toward the outside. Flash and/
or caulk pipe on outside wall. Install inlet air screen
assembly and fasten to pipe with screws. Insert a 3-foot
length of Type B vent pipe through the concentric vent box
opening (see Figure 32, p. 33, detail A) with the “UP”
arrow pointing toward the outside:
• Unit sizes 30–75: Insert a 3-foot length of 4-inch Type B
vent pipe
• Unit sizes 90–120: Insert a 3-foot length of 5-inch Type B
vent pipe.
Position the pipe to extend 12 inches beyond the inlet air
screen. Secure the Type B vent pipe in position by drilling
three small equally spaced holes through the collar of the
concentric vent box and inserting sheet metal screws.
Install deflector disk on Type B vent pipe 2-1/2 inches
(63.5 mm) from inlet air screen and fasten with screws.
Install vent terminal on end of Type B vent pipe, fasten
with screws and seal joint.
Connect flue pipe and combustion air pipe from concentric
vent box to unit, following instructions “Combustion Air
Venting and Piping,” p. 32 and“Exhaust Venting,” p. 32.
Joint between Type B vent pipe and single wall vent pipe
must be sealed with high temperature silicone sealant (see
Figure 33, p. 34). Collars on unit and on concentric vent
box are sized so that crimped ends of combustion air pipes
go toward the unit and crimped ends of flue pipes go away
from the unit.