Rheem RGLK, Installation Instructions Manual

Page: 11 / 36

Combustion air must be free of acid
forming chemicals; such as sulphur,
fluorine and chlorine. These elements
are found in aerosol sprays,
detergents, bleaches, cleaning
solvents, air fresheners, paint and
varnish removers, refrigerants and
many other commercial and household
products. Vapors from these products
when burned in a gas flame form acid
compounds. The acid compounds
increase the dew point temperature of
the flue products and are highly
corrosive after they condense.
ALL FURNACE INSTALLATIONS
MUST COMPLY WITH THE
NATIONAL FUEL GAS CODE AND
LOCAL CODES TO PROVIDE
ADEQUATE COMBUSTION AND
VENTILATION AIR FOR THE
FURNACE. FAILURE TO DO SO CAN
CREATE HAZARDOUS CONDITIONS
RESULTING IN PROPERTY
DAMAGE, BODILY INJURY OR
DEATH FROM SMOKE, FIRE OR
CARBON MONOXIDE.
Combustion air requirements are
determined by whether the furnace is
in an open (unconfined) area or in a
confined space such as a closet or
small room.
EXAMPLE 1.
FURNACE LOCATED IN AN
UNCONFINED SPACE
Using indoor air for combustion.
An unconfined space must have at
least 50 cubic feet for each 1,000 Btuh
of the total input for all appliances in
the space. Here are a few examples of
the room sizes required for different
inputs. The sizes are based on 8 foot
ceilings.
Btuh Minimum Sq. Feet Typical Room Size
Input With 8' Ceiling With 8' Ceiling
50,000 312 14
*
x24
*
or 18
*
x18
*
75,000 469 15
*
x31
*
or 20
*
x24
*
100,000 625 20
*
x31
*
or 25
*
x25
*
125,000 833 23
*
x34
*
or 26
*
x30
*
150,000 938 25
*
x38
*
or 30
*
x31
*
If the open space containing the
furnace is in a building with tight
construction (contemporary
construction), outside air may still be
required for the furnace to operate and
vent properly. Outside air openings
should be sized the same as for a
confined space.
11
WARNING
!
FIGURE 7
AIR FROM ATTIC/CRAWL SPACE
FURNACE LOCATED IN A
CONFINED SPACE
A confined space is any space smaller
than shown above as unconfined.
A. USING INDOOR AIR FOR
COMBUSTION
When using indoor air for
combustion a confined space must
have
two openings into the space.
One opening must be within 12
inches of the ceiling and the other
must be within 12 inches of the
floor.
The openings must be sized
by how they are connected to the
heated area or to the outside, and
by the input of all appliances in the
space.
The openings must each have at
least 100 square inches of free area.
Each opening must have at least
one square inch of free area for
each 1,000 BTUH of total input in
the space. Here are some typical
openings required.
Btuh Free Area
Input Each Opening
50,000 100 Square Inches
100,000 100 Square Inches
150,000 150 Square Inches
IMPORTANT: Do not take air from a
heated space with a fireplace, exhaust
fan or other device that may produce a
negative pressure.
B. USING OUTDOOR AIR FOR
COMBUSTION
The confined space must
communicate with the outdoors in
accordance with methods 1 or 2.
The minimum dimension of air
openings shall not be less than 3
inches. Where ducts are used, they
shall be of the same cross-sectional
area as the free area of the
openings to which they connect.
Method 1
Two permanent openings, one located
within 12 inches of the top and one
located within 12 inches of the bottom,
of the enclosure shall be provided. The
openings shall communicate directly,
or by ducts, with the outdoors or
spaces (crawl or attic) that freely
communicate with the outdoors.
a. Where directly communicating with
the outdoors or where
communicating to the outdoors
through vertical ducts, each opening
shall have a minimum free area of 1
square inch for each 4,000 BTUH of
total appliance input rating in the
enclosure. Here are some typical
sizes.
Btuh Free Area Round Pipe
Input Each Opening Size
50,000 12.5 Square Inches 4
(
75,000 18.75 Square Inches 5
(
100,000 25 Square Inches 6
(
125,000 31.25 Square Inches 7
(
150,000 37.5 Square Inches 7
(
b. Where communicating with outdoors
through horizontal ducts, each
opening shall have a minimum free
area of 1 square inch for each 2,000
BTUH of total input rating of all
equipment in the enclosure. Here
are some typical sizes.