Allied Air Enterprises 95G1UH, A95UH Vent Piping Guidelines, EXHAUST PIPE Horizontal Application

Vent Piping Guidelines

This gas furnace can be installed as either a Non-Direct Vent or a Direct Vent gas central furnace.

NOTE: In non-Direct Vent installations, combustion air is taken from indoors and flue gases are discharged outdoors. In Direct Vent installations, combustion air is taken from outdoors and flue gases are discharged outdoors.

Intake and exhaust pipe sizing - Size pipe according to Tables 4 and 5. Table 4 lists the minimum vent pipe lengths permitted. Table 5 lists the maximum pipe lengths permitted.

Regardless of the diameter of pipe used, the standard roof and wall terminations described in section Exhaust Piping Terminations should be used. Exhaust vent termination pipe is sized to optimize the velocity of the exhaust gas as it exits the termination. Refer to Table 6.

In some applications which permit the use of several different sizes of vent pipe, a combination vent pipe may be used. Contact Allied Air Technical Service for assistance in sizing vent pipe in these applications.

NOTE: The exhaust collar on all models is sized to accommodate 2” Schedule 40 vent pipe. When vent pipe which is larger than 2” must be used in an upflow application, a transition must be applied at the exhaust collar in order to properly step to the larger diameter vent pipe. Contact Allied Air Technical Service for more information concerning sizing of vent systems which include multiple pipe sizes.

EXHAUST PIPE

Horizontal Application

NOTE: All horizontal runs of exhaust pipe must slope back toward unit. A minimum of 1/4” (6 mm) drop for each 12” (305 mm) of horizontal run is mandatory for drainage.

NOTE: Exhaust pipe MUST be glued to furnace exhaust fittings.

NOTE: Exhaust piping should be checked carefully to make sure there are no sages or low spots.

Figure 20

IMPORTANT

Do not use screens or perforated metal in exhaust or intake terminations. Doing so will cause freeze-ups and may block the terminations.

Use the following steps to correctly size vent pipe diameter.

MINIMUM VENT PIPE LENGTHS

*Any approved termination may be added to the minimum length listed.

**This gas furnace must have 3" to 2" reducing ell (supplied or field replacement Canadian kit) installed directly into unit flue collar.

Table 4

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