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UBXC-UDXC-IOM (01-24) 1042980-0
INSTALLATION—CONTINUED
General Requirements for Vent Connections—Continued
Condensation Mitigation
⚠ CAUTION ⚠
• Failure to pitch the vent run properly may damage the heater due to condensate running back
into the unit.
• Exceeding vent pipe diameter and length requirements may result in condensate forming in the
vent pipe.
• For units with long vent runs—over 50% of maximum vent length allowed—or installed in low ambient conditions
(below 50°F (10°C), it is recommended that vent pipes be fitted at the low point of the vent system with a tee, a
drip leg, and a cleanout cap to prevent any moisture in the vent pipe from entering the unit. The drip leg should
be inspected and cleaned out periodically during the heating season.
• Any length of single-wall vent pipe exposed to cold air or run through an unheated area or an area with an ambient
temperature of 50°F (10°C) or less, must be insulated along its entire length with a minimum of 1/2-inch foil-faced
fiberglass, 1-1/2# density insulation.
• For horizontal vent runs, the flue pipe must be pitched down toward the terminal end—1/4-inch per foot for
condensate drainage—for the entire length of the horizontal vent run.
Vent System Support Requirements
⚠ CAUTION ⚠
• Do not rely on the heater to support either horizontal or vertical vent pipe.
• Use non-combustible supports on vent pipe.
• Support horizontal runs every 6 feet (1.8 meters).
• Support vertical runs in accordance with the pipe manufacturer’s requirements.
• Support single-wall pipe in accordance with accepted industry practice.
Vent System Sealing
Vent system joints depend on the type of pipe being used:
• Category III pipe: follow manufacturer’s instructions for joining pipe sections—connect venter outlet or the vent
cap using secure, sealed joints that follow a procedure best suited to the style of Category III pipe being used.
• Single-wall galvanized pipe (26-gauge or heavier): secure slip-fit connections using sheet metal screws or
rivets—seal all joints and seams using aluminum tape or silicone sealant.
• For Category I vents: when connecting Type B double-wall pipe to single-wall pipe or to the vent collar, use an
adapter made by the Type B double-wall pipe manufacturer for that purpose and follow the Type B double-wall
pipe manufacturer’s instructions.
• Double-wall Type B vent pipe: join pipe sections in accordance with the pipe manufacturer’s requirement—refer
to the illustrated instructions in Figure 8 to connect double-wall pipe to the heater collar, single-wall pipe, and vent
cap. Work quickly to assemble components before sealant dries.
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