VENT
COMBUSTION
AIR
2”
MIN.
FIGURE 34: Double Horizontal Combustion Air Intake and Vent Termination
MIN.
6”
FIGURE 35: Double Vertical Combustion Air Intake and Vent Termination
DOWNWARD VENTING
In some applications, it may be necessary to run the vent pipe and air intake downwards. If this is to be done, the following rules must be fol- lowed.
•A condensate trap hose must be connected to both the air intake pipe and the vent pipe at the lowest part of the horizontal run.
•The condensate drain trap must have a trap of a minimum of six inches.
•The total vertical downward distance must not exceed sixteen feet.
•The condensate drain hose must be connected to a condensate drain pump, a open or vented drain or into the condensate drain line from the furnace.
•The condensate drain lines must not pass through unconditioned spaces where the temperature may fall below freezing.
•The condensate drain line must be primed at the initial
COMBUSTION AIR SUPPLY
All installations must comply with Section 5.3, Air for Combustion and Ventilation of the National Fuel Gas Code, ANSI Z223.1 or Sections 7.2, 7.3 or 7.4 of CAN/CGA B149.1 or .2 Installation Code - latest edi- tions.
This furnace is certified to be installed with one of three possible com- bustion air intake configurations.
1.OUTDOOR COMBUSTION AIR: This is a direct vent configuration where the combustion air is supplied through a PVC or ABS pipe that is connected to the PVC coupling attached to the furnace and is terminated in the same atmospheric zone as the vent. This type of installation is approved on all models. Refer to Figure 36.
2.AMBIENT COMBUSTION AIR: Combustion air is supplied from the area surrounding the furnace through openings in the furnace casing. The combustion air and the vent pipes are not terminated in the same atmospheric zone. Refer to Figure 31 for vent termina- tions. Refer to "Ambient Combustion Air Supply" for proper installa- tion. Refer to Figure 27.
3.VENTILATED COMBUSTION AIR: Combustion air is supplied through a PVC or ABS pipe that is connected to the PVC coupling attached to the burner box and is terminated in a ventilated attic or crawl space. The combustion air and the vent pipes are not termi- nated in the same atmospheric zone. Refer to Figure 39 for attic and crawl space termination. Only the combustion air intake may terminate in the attic. The vent must terminate outside.
Outdoor Combustion Air
Combustion Air Intake/Vent Connections
This installation requires combustion air to be brought in from outdoors. This requires a properly sized pipe (Shown in Figure 36) that will bring air in from the outdoors to the furnace combustion air intake collar on the burner box. The second pipe (Shown in Figure 36) is the furnace vent pipe.
NOTICE
An optional plastic birdscreen is shipped in the loose parts bag with every furnace. This may be installed in the intake collar to prevent any small objects from entering the furnace.
The combustion air intake pipe should be located either through the wall (horizontal or side vent) or through the roof (vertical vent). Care should be taken to locate side vented systems where trees or shrubs will not block or restrict supply air from entering the terminal.
Also, the terminal assembly should be located as far as possible from a swimming pool or a location where swimming pool chemicals might be stored. Be sure the terminal assembly follows the outdoor clearances listed in Section #1 “Outdoor Air Contaminants.”
16’ MAX |
6” MIN. |
6” MIN. |
Connects to collar on top of burner box
Vent pipe cements into socket just above top panel
Or vent pipe may be clamped into outlet of drain coupling
FIGURE 36: Downward Venting
FIGURE 37: Direct Vent Air Intake Connection and Vent Connection
26 | Johnson Controls Unitary Products |