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8 • Residen al Standard Gas Water Heater Use and Care Guide
GETTING STARTED
8 • Residen al Standard Gas Water Heater Use and Care Guide
GETTING STARTED
Example:
Gas Burning Appliance BTU/HR Ra ng
Gas Water Heater 40,000
Furnace 75,000
Dryer 20,000
Total 135,000
Your Appliances:
Gas Burning Appliance BTU/HR Ra ng
Gas Water Heater
Total
Table 2 provides examples of minimum
square footage (area) required for
various BTU/HR totals. Areas used for
storage or which contain large objects
containing less air than is assumed for
the room sizes in Table 2 – see Op on
A for more specifi c calcula ons.
Op on A: Installa on without
outside ven la on (not recom-
mended)
Ven la on with outside air is recom-
mended for all installa ons. Even if
the water heater is installed in a large,
open room inside the house, outdoor
air is usually needed because modern
homes are very ghtly sealed and
o en do not supply enough air to the
water heater. However, when installed
in a large indoor space, it may be pos-
sible to provide enough air without
outside ven la on. If you are unsure if
your installa on loca on has enough
ven la on, contact your local gas
u lity company or code offi cials for a
safety inspec on.
The following instruc ons will help de-
termine if it may be possible to install
without outside ven la on. Even if
this may be possible, you will need to
conduct the vent dra test on pages
23-24 when installa on is fi nished. If
there is not enough ven la on, you
will need to ven late with outside air.
Check for Chemicals:
Installa ons where corrosive chemi-
cals may be present require outside
air. Air for combus on and ven la on
must be clean and free of corrosive or
acid-forming chemicals such as sulfur,
fl uorine, and chlorine. Ven la on with
outside air will reduce these chemicals,
but it may not completely eliminate
them. Failure due to corrosive chemi-
cals is not covered by the warranty.
Examples of loca ons that require
outside air due to chemicals include:
• Beauty salons
• Photo processing labs
• Indoor pools
• Laundry, hobby, or cra rooms
• Chemical storage areas
Products such as aerosol sprays, de-
tergents, bleaches, cleaning solvents,
gasoline, air fresheners, paint and
varnish removers, and refrigerants
should not be stored or used near the
water heater.
A1: Calculate the air volume of
the room
Air requirements depend on the size of
the room.
Floor Area (Square feet) X Ceiling
Height (feet) = Room Volume (cubic
feet)
If there are large objects in the room
(e.g., refrigerator, furnace, car), sub-
tract their volume from the volume of
the room to get a be er es mate of
the air available.
Room Volume – Object Volume = Air
Volume
Table 2
BTU/HR Minimum Square Typical Room
Input Feet with 8’ Ceiling with 8’ Ceiling
30,000 188 9 x 21
45,000 281 14 x 20
60,000 375 15 x 25
75,000 469 15 x 31
90,000 563 20 x 28
105,000 657 20 x 33
120,000 750 25 x 30
135,000 844 28 x 30
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