Bryant 340MAV instruction manual COMBUSTION-AIR and Vent Pipe Termination Clearances, Clearance FT

and Canada. In Canada construct all combustion-air and vent pipes for this unit of CSA or ULC listed schedule-40 PVC, PVC-DWV or ABS-DWV pipe and pipe cement. SDR pipe is NOT approved in Canada.

See Table 7 for maximum pipe lengths and Fig. 36, 37, 38, 39, and 40 for exterior piping arrangements.

NOTE: Furnace combustion-air and vent pipe connections are sized for 2-in. pipe. Any pipe size change should be made outside furnace casing in vertical pipe. (See Fig. 32.) This allows proper drainage of vent condensate.

Combustion-air and vent pipes must terminate together in same atmospheric pressure zone, either through roof or sidewall (roof termination preferred), using accessory termination kit. See Table 5 for required clearances.

Furnace combustion-air and vent pipe connections must be at- tached as shown in Fig. 27. Combustion-air intake plug fitting and inducer housing alternate vent cap may need to be relocated in some applications.

NOTE: Slope combustion-air and vent pipes a minimum of 1/4 in. per linear ft with no sags between hangers.

CAUTION: When combustion-air pipe is installed above a suspended ceiling, pipe must be insulated with 3/8-in. thick Armaflex-type insulation. Combustion-air pipe should also be insulated when it passes through warm, humid space.

→CAUTION: When vent pipe is exposed to temperatures below freezing, such as when it passes through an

unheated space or when a chimney is used as a raceway, pipe must be insulated as shown in Table 8 with Armaflex-type insulation. Failure to follow this caution will result in intermittent unit operation.

An abandoned masonry chimney may be used as a raceway for properly insulated and supported combustion-air and vent pipes. Each furnace must have its own set of combustion-air and vent pipes and be terminated individually, as shown in Fig. 42.

Other gas appliances with their own venting system may also use the abandoned chimney as a raceway providing it is permitted by local code, the current edition of the NFGC or NSCNGPIC, and the vent or liner manufacturer’s Installation Instructions. Care must be taken to prevent the exhaust gases from one appliance from contaminating the combustion air of other gas appliances.

CAUTION: Combustion air must not be taken from inside structure because inside air is frequently contami- nated 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 prod- ucts. Locate combustion-air inlet as far as possible from swimming pool and swimming pool pump house.

Excessive exposure to contaminated combustion air will result in safety and performance related problems.

WARNING: Solvent cements are combustible. Keep away from heat, sparks, and open flame. Use only in well ventilated areas. Avoid breathing in vapor or allowing contact with skin or eyes. Failure to follow this warning could result in fire, property damage, personal injury, or death.

WARNING: All combustion-air and vent pipes must be airtight and watertight. Pipes must also terminate exactly as shown in Fig. 36, 37, 38, 39, or 40. Failure to follow this warning could result in property damage, personal injury, or death.

TABLE 5—COMBUSTION-AIR AND VENT PIPE

TERMINATION CLEARANCES

LOCATION	CLEARANCE (FT)
	U.S.A.	Canada
Above grade level or above antici-	1	1†
pated snow depth
Water heater/Dryer vent	See Note 5	See Note 5
From plumbing vent stack	3	3
From any mechanical fresh air intake	See Note 4	6
For furnaces with an input capacity
equal to or less than 100,000
Btuh—from any non-mechanical air	1	1
supply (windows or doors which can
be opened) or combustion-air opening
For furnaces with an input capacity
greater than 100,000 Btuh-from any
nonmechanical air supply (windows or	1	3
doors which can be opened) or
combustion-air opening
From service regulator vent, electric	See Note 6	See Note 6
and gas meters, and relief equipment
Above grade when adjacent to public

NOT IN HORIZONTAL SECTION

FURNACE

PIPE DIAMETER

TRANSITION IN

VERTICAL SECTION

A93034

walkway Note 3 Note 3

† 18 in. above roof surface in Canada.

NOTES:

1. If installing 2 adjacent Furnaces, refer to Multiventing and Vent Terminations

section for proper vent configurations.

2. When locating combustion-air and vent terminations, consideration must be

given to prevailing winds, location, and other conditions which may cause

recirculation of the appliance’s own flue products or the flue products of

adjacent vents. Recirculation can cause poor combustion, inlet condensate

problems, and accelerated corrosion of heat exchangers.

3. Vent termination can not terminate less than 2 ft horizontal and 7 ft above

public walkway or where condensate vapor or droplets may be a hazard.

4. Vent termination must be at least 3 feet above any forced draft inlets within

10 feet horizontal. Vent termination must be at least 3 feet horizontal from

other direct vent appliances intake unless otherwise specified by manufac-

turer.

5. 3 ft radius of furnace air-intake terminal and 1 ft horizontally from vertical

Fig. 32—Combustion-Air and Vent Pipe Diameter

Transition Location and Elbow Configuration

centerline of furnace air-intake terminal.

6. Above a meter/regulator within 3 feet horizontally of vertical centerline of

meter/regulator vent outlet to a maximum vertical distance of 15 feet.

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