C199 Manual 9
Combuson Air Requirements (Common Vent Applicaons Only)
Combuson air provided to the appliance should
not be taken from any area of the structure that
may produce a negave pressure (i.e. exhaust fans,
powered venlaon fans).
NOTICE
Using Indoor Air For Combuson
When using air from other room(s) in the building,
the total volume of the room(s) must be of adequate
volume (Greater than 50 cubic feet per 1000 Btu/hr).
Each Combuson air opening must have at least one
square inch of free area for each 1000 Btuh, but not
less than 100 square inches each.
When communicang directly with the outdoors
through horizontal ducts, each opening shall have a
minimum free area of 1 in
2
/2000 Btu/hr (1100 mm
2
/
kW) of total input rang of all appliances in the
conned space.
Note: If ducts are used, the cross seconal area of the
duct must be greater than or equal to the required
free area of the openings to which they are
connected.
When communicang indirectly with the outdoors
through vercal ducts, each opening shall have a
minimum free area of 1 in
2
/4000 Btu/hr (550 mm
2
/
kW) of total input rang of all appliances in the
conned space. Combuson air to the appliance can
be provided from a well venlated ac or crawl
space.
WARNING
TO PREVENT POSSIBLE PERSONAL INJURY OR DEATH
DUE TO ASPHYXIATION,
COMMON VENTING WITH OTHER MANUFACTURER’S
INDUCED DRAFT APPLIANCES IS NOT ALLOWED.
□ Verify proper clearances around the vents .
□ Ensure that the Combuson Air Requirements are
followed that will provide sucient combuson
air for the appliance.
□ Ensure approved venng components have been
used.
□ All horizontal vent runs must be sloped up away
from the water heater a minimum of 1/4 “ (6 mm)
per foot.
□ Verify that there is adequate combuson air.
□ Ensure that room air is only ulized in common
vented applicaons.
□ Ensure if installed in common vent applicaon
ulizing room air that exhaust is terminang
vercally only. (Reference Common Vent manual
for further details.)
□ Installaon complies with Naonal Fuel Gas
Code, ANSI Z223.1/NFPA 54 as well as local and
state regulaons therein.
Checklist for Combuson Air and
Venng Requirements
Exhaust
(Be sure to also maintain 12” above grade or
ancipated snow level)
Vent terminaon per ANSI Z223.1/NFPA 54.
For clearances not specied in ANSI Z223.1/
NFPA 54, clearances are in accordance with
local installaon codes and the require-
ments of the gas supplier.