Installation & Operation Manual
2
Venting
(continued)
19
The sidewall or vertical rooftop DirectAire™ combustion air supply system has specific material and installation requirements. The
air inlet pipe connects directly to the unit to supply combustion air. In most installations, the combustion air inlet pipe will be a
dedicated system with one air inlet pipe per unit. You can combine multiple air inlets if the guidelines in Combined Air Inlet Points,
page 20 are followed. The air inlet pipe will be connected to a combustion air inlet cap as specified in this section.
For normal installations, this system uses a single-wall pipe to supply combustion air from outdoors directly to the unit.
In cold climates, use a Type-B double-wall vent pipe or an insulated single-wall pipe for combustion air. This will help prevent
moisture in the cool incoming air from condensing and leaking from the inlet pipe.
Length of air inlet pipe
The installed length of air inlet pipe from the unit to the outside air inlet cap must not exceed 50 equivalent feet (15.2m). Subtract
5 feet (1.5m) of equivalent length for each 90° elbow. Subtract 2.5 feet (0.7m) of equivalent length for each 45° elbow.
Do not exceed the limits for the combustion air inlet piping lengths.
Sidewall air inlet
The sidewall air inlet cap is supplied in the Sidewall Air Inlet Kit. Order the kit from the appliance manufacturer. This sidewall cap
supplies combustion air for a single unit only. See Table 2B, page 21, for kit numbers.
Locate the unit as close as possible to the sidewall where you will install the combustion air supply system.
WARNING
Locate and install the combustion air inlet cap correctly. Failure to do so can allow the discharge of flue products
to be drawn into the combustion process. This can result in incomplete combustion and potentially hazardous
levels of carbon monoxide in the flue products. This will cause operational problems and the spillage of flue
products. Spillage of flue products can cause personal injury or death due to carbon monoxide poisoning.
Combustion air inlet piping
Figure 2-6_Air Inlet Cap for Sidewall Termination
Figure 2-5_Sidewall Combustion Air Inlet
Vertical DirectAire ™ venting -
see page 14.
The Vertical DirectAire™ vent system is the same as the Conventional Negative Draft vent system, except it pulls
combustion air from the outdoors through a separate air inlet pipe. Follow all requirements in the Conventional
Negative Draft Venting section on page 16.
The Vertical DirectAire™ vent system requires you to install two pipes directly to the unit; one vertical pipe with
a rooftop termination for the flue products and one pipe for combustion air. For this venting option, you must
purchase the DV box adapter from the appliance manufacturer. The DV box attaches to the air inlet of the unit. The
pipe for combustion air attaches to the DV box (see FIG. 2-11 on page 28). Reference page 28 for a list of approved
air intake materials.
B
NOTICE
Before installing a venting system, follow requirements found in the General Venting section.
