Operating instructions
CAUTION: If a fireplace or a kitchen or bathroom exhaust fan is used, an outside air intake should be installed. These
devices rob the boiler and water heater of combustion air.
Enough fresh air must be provided to assure proper combustion. The fire in the boiler uses oxygen. It must have a continuous supply. The air in
a house contains only enough oxygen to supply the burner for a short time. Outside air must enter the house to replace that used by the burner.
The exact fresh air requirements depend on whether the boiler is located in an unconfined or confined space.
A. BOILER LOCATED IN UNCONFINED SPACE
An unconfined space is defined as a space with volume not less than 50 cu ft per 1000 Btuh of total input rating of all appliances installed in that
space.
If boiler is in an open area (unpartitioned basement) in a conventional house, air that leaks through cracks around doors and windows will usually
be adequate to provide air for combustion. The doors should not fit tightly. Cracks around windows should not be caulked.
B. BOILER LOCATED IN CONFINED SPACE
ALL AIR FROM INSIDE BUILDING
The confined space shall be provided with 2 permanent openings communicating directly with an additional room(s) of sufficient volume so that
the combined volume of all spaces meets the criteria for an unconfined space. The total input of all combustion equipment installed in the combined
space shall be considered in making this determination. Each opening shall have a minimum free area of 1 sq in. per 1000 Btuh of total input rating
for all combustion equipment in the confined space, but not less than 100 sq in. One opening shall be within 12 in. of the top and 1 within 12 in.
of the bottom of the enclosure. (See Fig. 5.)
Example: The boiler is rated at 100,000 Btuh. The water heater is rated at 30,000 Btuh. The total is 130,000 Btuh. Two grilles are needed, each
with 130 sq in. of FREE opening. Metal grilles have about 60 percent FREE area. To find the louvered area needed, multiply the FREE area
required by 1.7 (130 X 1.7 = 221.0 sq in. louvered area). In this example, 2 grilles each having an 8 in. X 30 in. (240 sq in.) louvered area would
be used. Fig. 5 shows grille locations.
ALL AIR FROM OUTDOORS
The confined space shall be provided with 2 permanent openings, 1 commencing within 12-in. of the top and 1 commencing within 12-in. of the
bottom of the enclosure. The openings shall communicate directly, or by ducts, with the outdoors or spaces (crawl or attic) that freely communicate
with the outdoors.
1. When directly communicating with the outdoors, each opening shall have a minimum free area of 1 sq in. per 4000 Btuh of total input rating
of all equipment in the enclosure.
2. When communicating with the outdoors through vertical ducts, each opening shall have a minimum free area of 1 sq in. per 4000 Btuh of
total input rating of all equipment in the enclosure.
3. When communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of 1 sq in. per 2000 Btuh
of total input rating of all equipment in the enclosure.
4. When ducts are used, they shall be of the same cross-sectional area as the free area of the openings to which they connect. The minimum
dimension of rectangular air ducts shall not be less than 3-in.
Fig. 4—General Principal Requirements for a Typical Installation
A98268
TO OUTSIDE
OIL
FILTER
SHUTOFF
VALVE
OIL
TANK
VENT PIPE
OIL BURNER
OIL LINES
VENT PIPE
MINIMUM 2 IN. ID
2 IN. FILL PIPE
AUTOMATIC
FILL VALVE
AND SHUTOFF
DIAPHRAGM
EXPANSION TANK
DRAFT
REGULATOR
FOUNDATIONS
ELECTRIC LINE
SERVICE LINE
ENTRANCE
SWITCH
OVERCURRENT
PROTECTED
SAFETY SWITCH
LINES TO OTHER
APPLIANCES
C
H
I
M
N
E
Y
FROM RADIATION
CIRCULATING
PUMP IN
RETURN LINE
RELIEF VALVE
TO RADIATION
—6—