Bryant 355CAV Combustion Air Pipe, Combustion Air and Vent Pipe Transition, Unit Corrosion Hazard

NOT IN HORIZONTAL SECTION

FURNACE

PIPE DIAMETER

TRANSITION IN

VERTICAL SECTION

A93034

NOTE: Select 1 vent pipe connection and￿ NOTE: Select 1 vent pipe connection and￿
1 combustion-air pipe connection.		1 combustion-air pipe connection.
AIR￿
COMBUSTION-￿ FLOW	COMBUSTION-￿
AIR	AIR	VENT
VENT				VENT
	VENT
		COMBUSTION-￿		COMBUSTION-￿
		AIR	AIR￿	AIR
			FLOW
UPFLOW		DOWNFLOW

355CAV

Fig. 38 - Combustion Air and Vent Pipe Transition

Location and Elbow Configuration

!CAUTION

UNIT OPERATION HAZARD

Failure to follow this caution may result in intermittent unit operation.

When installing combustion air and vent system of short pipe length, the smallest allowable pipe diameter must be used.

!CAUTION

UNIT CORROSION HAZARD

Failure to follow this caution may result in unit component damage.

Excessive exposure to contaminated combustion air may result in safety and performance related problems. Combustion air must not be taken from inside structure because that air is frequently contaminated by halogens, which include fluorides, chlorides, bromides, and iodides. These elements are found in aerosols, detergents, bleaches, cleaning solvents, salts, air fresheners, adhesives, paint, and other household products. Locate combustion-air inlet as far as possible from swimming pool and swimming pool pump house.

EXAMPLE: This 80,000 BTUH furnace located in Indianapolis, elevation 650 ft above sea level, could be installed as a direct vent/2-pipe system that requires 3 elbows and 17 ft of vent pipe, along with 5 elbows and 16 ft of combustion-air pipe. Table 7 indicates this application would allow a 1-1/2-in. diameter vent pipe, but require a 2-in. diameter combustion air pipe. According to Table 7, 1-1/2-in. diameter pipe is good for 20 ft with 3 elbows, but only 10 ft with 5 elbows. Therefore, 2-in. diameter pipe must be used for both vent and combustion-air pipes since the largest required diameter must always be used for both pipes. If the same installation was made in Albuquerque, elevation 5250 ft above sea level, installation would require 2- in. diameter vent pipe and combustion-air pipe. At 5001 to 6000-ft elevation, 1-1/2-in. pipe is not allowed with 5 elbows, but 2-in. pipe is good for 68 ft with 5 elbows are required.

COMBUSTION AIR PIPE

General

Furnace combustion-air connection must be attached as shown in Fig. 39. Combustion-air intake housing plug may need to be relocated in some applications.

		COMBUSTION-￿
COMBUSTION-￿		AIR
AIR	VENT	VENT

AIR￿	AIR￿
FLOW	FLOW

HORIZONTAL-LEFT DISCHARGE HORIZONTAL-RIGHT DISCHARGE

A96187

Fig. 39 - Combustion Air and Vent Pipe Connections

NOTE: All pipe joints must be cemented except attachment of combustion-air pipe to inlet housing connection, since it may be necessary to remove pipe for servicing.

NOTE: A 2-in. diameter pipe must be used within the furnace casing. Make all pipe diameter transitions outside furnace casing.

Attachment of Combustion Air Pipe

NOTE: Combustion air pipe system has the same diameter and same length as the vent pipe as mentioned in section “Combustion- -Air and Vent Pipe Diameter.”

1.Determine location of combustion-air intake pipe connection to combustion-air intake housing as shown in Fig. 39 for application.

2.Verify combustion-air intake housing plug fitting is installed in appropriate unused intake housing connection.

3.Install combustion-air pipe grommet (factory-supplied in loose parts bag) into selected furnace casing combustionair pipe hole.

4.Determine the number of combustion air disk halves to be installed in the combustion air intake housing. Insert perforated disk half or assembly (factory supplied in loose parts bag) in intake housing where combustion-air intake pipe will be connected.

5.Insert assembled combustion air inlet pipe into intake housing as shown in Fig. 39.

NOTE: Do not cement combustion air intake pipe permanently to combustion air intake housing since it may be necessary to remove pipe for service of igniter or flame sensor.

6.Drill a 1/8-in. hole in 2-in, combustion air pipe using the hole in intake housing as a guide.

7.Install a field-supplied No. 6 or No. 8 sheet metal screw into combustion air pipe.

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