800SA/801SA: Installation, Start–Up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
6
b. Not less than the sum of the areas of all vent connectors in the
space.
*Minimum dimensions of 3 in. (76 mm).
NOTE:
Use any of the following combinations of openings:
A&B, C&D, D&E, F&G
A03174
Fig. 6 – Air for Combustion, Ventilation,
and Dilution for Outdoors
The opening shall commence within 12” (300 mm) of the ceiling.
Appliances in the space shall have clearances of at least 1” (25 mm)
from the sides and back and 6” (150 mm) from the front. The opening
shall directly communicate with the outdoors or shall communicate
through a vertical or horizontal duct to the outdoors or spaces (crawl or
attic) that freely communicate with the outdoors.
– In
door Combustion Air
NFPA & AGA
–
Standard and Known-Air-Infiltration Rate
Methods
– I
ndoor air
is permitted for combustion, ventilation, and dilution, if
the
Standard
or
Known-Air-Infiltration
Method is used.
The Standard Method
Use the
Standard Method
if:
1. The space has no less volume than 50 cubic feet per 1,000 Btuh of
the maximum input ratings for all gas appliances installed in the
space and
2. The air infiltration rate is not known to be less than 0.40 air changes
per hour (ACH).
Use the
Known Air Infiltration Rate Method
if the infiltration rate is
known to be:
1. Less than 0.40 ACH and
2. Equal to or greater than 0.10 ACH
Infiltration rates greater than 0.60 ACH shall not be used. The minimum
required volume of the space varies with the number of ACH and shall
or Equations 1 and 2. Determine the minimum
required volume for each appliance in the space and add the volumes
together to get the total minimum required volume for the space.
- Minimum Space Volumes were determined by using the
following equations from the current edition of National Fuel Gas Code
ANSI Z223.1/NFPA 54:
1. For other than fan-assisted appliances, such as a draft
hood-equipped water heater:
A04002
1 SQ IN.
PER
4000
BTUH*
DUCTS
TO
OUTDOORS
1 SQ IN.
PER 4000
BTUH*
CIRCULA
TING
AIR DUCTS
VENT
THROUGH
ROOF
D
B
A
C
E
1 SQ IN.
PER 4000
BTUH*
DUCT
TO
OUTDOORS
CIRCULATING AIR DUCTS
1 SQ IN.
PER 2000
BTUH*
1 SQ IN.
PER 2000
BTUH*
DUCTS
TO
OUTDOORS
12
″
MAX
12
″
MAX
12
″
MAX
12
″
MAX
12
″
MAX
OUTDOORS
1 SQ IN.
PER
4000
BTUH*
F
G
CLEARANCE IN FRONT
OF COMB
USTION AIR
OPENINGS SHALL BE
AT LEAST 3 IN.
(305mm)
(305mm)
(305mm)
(305mm)
(305mm)
(76mm)
WARNING
!
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in death and/or personal
injury.
Many homes require air to be supplied from outdoors for furnace
combustion, ventilation, and dilution of flue gases. The furnace
combustion air supply must be provided in accordance with this
instruction manual.
Table 1 – Minimum Free Area Required for Each Combustion Air Opening or Duct to Outdoors
FURNACE
INPUT (BTUH)
TWO HORIZONTAL DUCTS
(1 SQ. IN./2,000 BTUH)
(1,100 SQ. MM/KW)
SINGLE DUCT OR OPENING
(1 SQ. IN./3,000 BTUH)
(734 SQ. MM/KW)
TWO OPENINGS OR VERTICAL DUCTS
(1 SQ. IN./4,000 BTUH)
(550 SQ. MM/KW)
Free Area of Opening
and Duct
(sq. in. / sq. mm)
Round Duct Diameter
(in./mm)
Free Area of Opening
and Duct
(sq. In. / sq. mm)
Round Duct Diameter
(in. / mm)
Free Area of
Opening and Duct
(sq. In. / sq. mm)
Round Duct Diameter
(In./mm)
44,000
22 (14193)
6 (152)
14.7 (9484)
5 (127)
11 (7097)
4 (102)
66,000
33 (21290)
7 (178)
22 (14193)
6 (152)
16.5 (10645)
5 (127)
88,000
44 (28387)
8 (203)
29.3 (18903)
7 (178)
22 (14193)
6 (152)
110,000
55 (35484)
9 (229)
36.7 (23677)
7 (178)
27.5 (17742)
6 (152)
132,000
66 (42581)
10 (254)
44 (28387)
8 (203)
33 (21290)
7 (178)
154,000
77 (49677)
10 (254)
51.3 (33096)
9 (229)
38.5 (24839)
8 (203)
EXAMPLES: Determining Free Area
FURNACE
WATER HEATER
TOTAL INPUT
110,000
+
30,000
=
(140,000 divided by 4,000)
=
35.0 Sq. In. for each two Vertical Ducts or Openings
66,000
+
40,000
=
(106,000 divided by 3,000)
=
35.3 Sq. In. for a Single Duct or Opening
88,000
+
30,000
=
(118,000 divided by 2,000)
=
59.0 Sq. In. for each of two Horizontal Ducts
Volume
Other
= 21ft
3
ACH
I
other
1000 Btu/hr
