Air For Combustion And Ventilation - Bryant 312A Installation, Start-Up, Operating And Service And Maintenance Instructions

equipped with means to prevent operation of either unit unless
the damper is in the full- -heat or full- -cool position.
AIR FOR COMBUSTION AND
VENTILATION
Provisions for adequate combustion, ventilation, and dilution air
must be provided in accordance with:
U.S. installations: Section 8.3 of the NFGC, Air for Combustion
and Ventilation, and applicable provisions of the local building
codes.
Canadian installations: Part 8 of the CAN/CSA- -B149.1- -05,
Venting Systems and Air Supply for Appliances and all
authorities having jurisdiction.
CAUTION
!
FURNACE CORROSION HAZARD
Failure to follow this caution may result in furnace damage.
Air for combustion must not be contaminated by halogen
compounds, which include fluoride, chloride, bromide, and
iodide. These elements can corrode heat exchangers and
shorten furnace life. Air contaminants are found in aerosol
sprays, detergents, bleaches, cleaning solvents, salts, air
fresheners, and other household products.
WARNING
!
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal
injury or death.
The operation of exhaust fans, kitchen ventilation fans,
clothes dryers, attic exhaust fans or fireplaces could create a
NEGATIVE PRESSURE CONDITION at the furnace.
Make- -up air MUST be provided for the ventilation devices,
in addition to that required by the furnace. Refer to Carbon
Monoxide Poisoning Hazard warning in venting section of
these instructions to determine if an adequate amount of
make- -up air is available.
Table 2 – Minimum Free Area Required for Each Combustion Air Opening or Duct to Outdoors
TWO HORIZONTAL DUCTS
(1 SQ. IN./2,000 BTUH)
FURNACE
(1,100 SQ. MM/KW)
INPUT
(BTUH)
Free Area of
Opening and Duct
(Sq. In.)
44,000 22
66,000 33
88,000 44
110,000 55
132,000 66
154,000 77
FURNACE WATER HEATER
110,000 + 30,000
66,000 + 40,000
88,000 + 30,000
SINGLE DUCT OR OPENING
(1 SQ. IN./3,000 BTUH)
(734 SQ. MM/KW)
Free Area of
Round Duct
Opening and Duct
(in. Dia)
(sq. In.)
6 14.7
7 22
8 29.3
9 36.7
10 44
10 51.3
TOTAL INPUT
= (140,000 divided by 4,000)
= (106,000 divided by 3,000)
= (118,000 divided by 2,000)
The requirements for combustion and ventilation air depend upon
whether or not the furnace is located in a space having a volume
of at least 50 cubic feet per 1,000 Btuh input rating for all gas
appliances installed in the space.
S Spaces having less than 50 cubic feet per 1,000 Btuh require the
Outdoor Combustion Air Method.
S Spaces having at least 50 cubic feet per 1,000 Btuh may use the
Indoor Combustion Air, Standard or Known Air Infiltration
Method.
Outdoor Combustion Air Method
1. Provide the space with sufficient air for proper
combustion, ventilation, and dilution of flue gases using
permanent horihorizontal or vertical duct(s) or opening(s)
directly communicating with the outdoors or spaces that
freely communicate with the outdoors.
2. Fig. 7 illustrates how to provide TWO OUTDOOR
OPENINGS, one inlet and one outlet combustion and
ventilation air opening, to the outdoors.
a. One opening MUST commence within 12 in. (300 mm)
of the ceiling and the second opening MUST commence
within 12 in. (300 mm) of the floor.
b. Size openings and ducts per Fig. 7 and Table 2.
c. TWO HORIZONTAL DUCTS require 1 square inch of
free area per 2,000 Btuh (1,100 mm2/kW) of combined
input for all gas appliances in the space per Fig. 7 and
Table 2.
d. TWO OPENINGS OR VERTICAL DUCTS require 1
square inch of free area per 4,000 Btuh (550 mm2/kW)
for combined input of all gas appliances in the space per
Fig. 7 and Table 2.
3. ONE OUTDOOR OPENING requires:
a. 1 square inch of free area per 3,000 Btuh (734 mm2/kW)
for combined input of all gas appliances in the space per
Table 2 and
b. Not less than the sum of the areas of all vent connectors
in the space.
TWO OPENINGS OR VERTICAL
Free Area of
Round Duct
Opening and Duct
(in. Dia)
5
6
7
7
8
9
= 35.0 Sq. In. for each two Vertical Ducts or Openings
= 35.3 Sq. In. for a Single Duct or Opening
= 59.0 Sq. In. for each of two Horizontal Ducts
8
DUCTS
(1 SQ. IN./4,000 BTUH)
(550 SQ. MM/KW)
Round Duct
(In. Dia)
(Sq. In.)
11 4
16.5 5
22 6
27.5 6
33 7
38.5 8