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1. Follow all local codes, or in the absence of local
codes, follow the most recent edition of the
National Fuel Gas Code: ANSI Z223.1/NFPA 54
in the USA or CAN/CSA B149.1 Natural Gas,
Propane Installation Code in Canada.
2. When installed indoors, the water heater shall be
located in an area to maintain the following
minimum clearances around the unit:
Keep the following
clearances.
The water heater location must provide enough air for proper combustion and ventilation of the
surrounding area. See the latest edition of ANSI Standard Z223.1 or any applicable local codes.
In general, these requirements specify that if the unit is installed in a confined space, there must
be a permanent air supply opening.
Minimum recommended air supply opening size for water heater:
Water heater size
MAX
240,000 BTU/h
Combustible Air Supplied by Mechanical fan or Make up air device
The water heater is equipped with a combustible air sensor that will shut off the unit when
inadequate combustible air supply to unit is detected.
If a mechanical fan or make up air device is used to supply air to the water heater or
utility room, the installer should make sure it does not create drafts which could cause
nuisance shutdowns.
If a blower is necessary to provide adequate combustion air to the water heater, the
blower and water heater must be set up so that the water heater cannot fire unless the
blower is operating.
sensors/transmitters and relays.
INDOOR INSTALLATION
Combustion Air Supply
When drawing make-up air from
outside the building
16.0 Sq. IN
When combustion air is supplied
from outside the building, an
opening communicating directly
with the outside should have a
minimum
free
area
square inch per 15,000 BTUH
input of the total input rating of
water heater in the enclosed
area.
Possible methods include the use of external flow
Side 2"
Front 4"
(24" Recommended
for Maintenance)
When drawing make-up air from inside
the building (from other rooms within)
When combustion air is supplied from
inside
communicating with the rest of the
dwelling should have a minimum free
area of one square inch per 1,000
of
one
BTUH input of the total input rating of
water heater in the enclosed area.
This opening should never be less
than 199 sq. in.
- 9 -
Top 12"
Bottom 12"
240 Sq. IN
the
building,
an
Back 1"
Side 2"
opening
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