Table of Contents
Advertisement
DIRECT-VENT TERMINATION
You may terminate vent and combustion air pipes either
vertically (through the roof) or horizontally (through a
sidewall). Vertical (through the roof) venting is preferred
because it offers protection from pipe damage and
condensate damage.
termination except on 126,000 BTU input furnaces. Follow
the instructions supplied with the concentric-vent kit.
For vertical direct venting, combustion-air-inlet pipe must
terminate next to vent pipe and 12 inches above roof (18" in
Canada) or highest expected snow accumulation. Extend
vent pipe at least 6 inches above combustion air inlet. See
Figure 13a for vertical direct vent termination.
Figure 13a. Vertical Termination for Direct Venting.
Combustion-air-inlet termination must always be pointed
downward to keep out rain and snow. Furnace will not
operate properly with water in combustion compartment.
Note: When properly installed, vent pipe is designed to
drain condensate and will not be affected by rainwater.
For horizontal direct venting, combustion-air inlet must
terminate next to vent pipe and at least 12 inches above
grade or highest expected snow accumulation. Extend vent
pipe at least 12 inches above combustion-air inlet. See
Figure 13b.
Figure 13b. Horizontal Termination for Direct Venting.
Attach a combustion-air pipe to combustion-air-inlet collar
located on top of furnace burner enclosure. Seal air pipe to
collar with RTV silicone caulk. See Figure 14.
Installer's Information Manual
You may use concentric vent
Note: When venting with 3-inch pipe, a 3" X 2" reducer must
be used.
Locate reducer as close as possible to
combustion-air inlet. You may use up to 20" of 2-inch pipe.
Figure 14. Combustion-Air Pipe Connection to Furnace for
Direct Vent.
NON-DIRECT VENTING (one pipe system)
DETERMINING VENT LENGTH
See Table 2 for maximum vent pipe length. Include any
termination elbows when determining maximum allowable
vent length. Minimum pipe length is five feet with 1 elbow.
Table 2 shows the maximum allowable pipe lengths for
non-direct vent systems depending on:
??
altitude (elevation) of the installation
??
gas input rating of furnace
??
diameter of the air and vent pipes
??
number of elbows
Note that some of the larger furnace models may require a
high altitude pressure switch at elevations between 3000
and 6000 feet. For example, the chart shows that the
126,000 Btu/hr model may need a high altitude pressure
switch when installed at elevations between 3000 and 4000
feet. Above 4000 feet, this model requires a high altitude
switch for all installations.
All furnace models require the high altitude pressure switch
when installed at elevations above 6000 feet.
The high altitude pressure switch is supplied with the LP
Conversion Kit #4226000 and the Natural Gas Conversion
Kit #4225600.
These kits also contain the other
components required for furnace installation at high
elevations.
NOTE: Table 2 assumes Sweep 90? elbows like that in
Figure 12a. If using Hard 90? elbows similar to the one in
Figure 12b, decrease the vent length by 3 feet for every
elbow used.
Page 13
Advertisement
Table of Contents
