Service manual

SECTION 8: VENTING
33
8.5 Unvented Operation Tube Termination
Turndown type vent terminal with a screen must be
installed at the exhaust end of the tube. Vent terminal
design shall not incorporate backdraft flap.
FIGURE 20: Tube Termination
8.6 Length Requirements
The maximum vent length allowed is 45' (13.7 m).
The maximum outside air supply duct length allowed
is 45' (13.7 m).
The total vent length, plus outside air duct length,
plus any extensions to minimum heat exchanger
lengths, cannot exceed 65' (19.8 m).
Vent length should be limited to less than 20' (6 m). If
using vent lengths greater than 20' (6 m),
condensation will form in the vent pipe. Insulation
and additional sealing measures (high temperature
silicone at all seams) are required. Optional heat
exchanger beyond minimum lengths is considered as
vent length for length determination.
Subtract 15' (4.6 m) of maximum allowed vent or duct
length per vent elbow if more than two are used.
8.7 Horizontal Ventilation 4" (10 cm) Pipe
8.8 Vertical Ventilation 4" (10 cm) Pipe
4" Single Wall Pipe
Vent Adapter
Vent Terminal
Combustible or
Non-Combustible Wall
Vent Adapter
18" Min.
Vent Terminal
4" Single Wall Pipe
Non-Combustible Wall Only
SIDE VIEW
Description Part Number
Vent Terminal (Comb. Wall) 90502100
Vent Terminal 02537801-XX
Wall Thimble 90505600
4" (10 cm) Single Wall Pipe
4" (10 cm) Type "B" vent cap
Roof
Roof
Flashing
Approved
Thimble
(If Applicable)
18" (46 cm)
Min.
4" (10 cm) Type "B" vent pipe
The last section of vent pipe
passing through the roof or
wall may be Type "B" vent pipe.
All other vent materials in the
building must be single wall
vent pipe.
Vent Adapter
SIDE VIEW
Description Part Number
Vent Cap 4" (10 cm) 90502300