INSTALLATION” under the “NON-DIRECT VENTING” instructions.

A non-direct vented furnace takes all air for combustion from the room in which furnace is installed. Non-direct venting requires only one pipe for venting the flue gases to the outdoors but you must make sure there is enough air for combustion and ventilation.

DIRECT VENTING INSTRUCTIONS (two pipe system)

DETERMINING VENT LENGTH

See Table 1 for maximum vent and combustion-air pipe length. Include any termination elbows when determining maximum allowable vent length. Minimum vent length is five feet with 0 elbows.

Table 1 shows the maximum allowable pipe lengths for 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 table 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 1 assumes Sweep 90? elbows like that in

Figure 3a. If using Hard 90? elbows similar to the one in Figure 3b, decrease the vent length by 3 feet for every elbow used.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(a)

 

 

(b)

Figure 3. (a) Sweep 90? Elbow. (b) Hard 90? Elbow.

When using a concentric vent kit the following exceptions apply:

??90,000 BTU input furnaces must be vented with 3-inch pipe.

??For 108,000 BTU input furnaces, reduce the maximum vent length by 5 feet when 2 sweep elbows are used, 10 feet when 3 sweep elbows are used, 15 feet when 4 sweep elbows are used and so on. For hard 90° elbows reduce vent length in 8 -foot intervals.

??126,000 BTU input furnaces may not be vented using a concentric vent.

Installer’s Information Manual

Page 7