Page 12
every foot of horizontal run. Flue pipe or vent connec-
tor must be inserted into but not beyond the outside
wall of the chimney flue.
Where two or more appliances vent into a common flue,
the area of the common flue should be at least equal to the
area of the largest flue or vent connector, plus 50% of the
area of any additional flues or vent connectors.
Inspect flue pipe annually. Clean soot or ash from flue pipe,
if necessary. If pipe is rusted, replace.
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1" (25mm)
min
Figure 15
COMBUSTIBLE
MATERIAL
Radiation Shield Installation
OHR23 UNIT (TOP)
RADIATION
SHIELDS
RADIATION SHIELDS
(SEE NOTE 1)
FLUE
PIPE
UNIT
CABINET
NOTE 1−Radiation shields must be constructed of 24 gauge sheet metal
minimum
.
NOTE 2−Radiation shields required when A is less than 9" (229mm).
NOTE 3−Radiation shields should extend from the top of the unit to the top of the flue pipe.
NON−
COMBUSTIBLE
SPACERS
OHR23 UNIT (FRONT)
12"
(305mm)
7" (178
mm)
SEE NOTE 3
SEE NOTE 2
A
A
B
Oil Supply Lines Sizing
Ensure that the restrictions of the piping system, plus any
lift involved, do not exceed the capability of the oil pump.
Use the following guidelines when determining whether to
use a single−or two−stage oil pump.
One−Pipe System
When using a one−pipe system with the oil tank even above
the burner and a vacuum of 6" (152 mm) Hg or less, a single−
stage fuel pump with a supply line and no return line should
be adequate. See figure 16. Manual bleeding of the fuel
pump is required on initial start up. Failure to bleed air from
the oil pump could result in an air lock/oil starvation condition.
NOTE − As an extra precaution, cycle heating on and off
ten times after bleeding air from the oil pump. This will
eliminate air in the gun assembly.
Figure 16
Oil Piping
One-Pipe System
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air
vent
fill
pipe
Oil
Tank
fuel
pump
Aux
Filter
Shut−off
Valve
8 FT (2.4 M)
MAXIMUM
ONE PIPE LIFT
Table 4
One−pipe Oil Sizing
Line Length
Pipe Diameter (OD Tubing)
0−50’ (15 m)
3/8" (10 mm)
51−100’ (15 m)
1/2" (12 mm)
Two−Pipe System
When using a two−pipe system with the oil tank below the
level of the burner, a single−stage fuel pump should be
used in lift conditions of up to 10 feet (3 m) and/or a vacu-
um of 10" (254 mm) Hg or less. See figure 17. Use a two−
stage fuel pump when lift exceeds 10 feet (3 m) and/or a
vacuum of 10" (254 mm) Hg to 15" (381 mm) Hg. Both con-
ditions require that you use a two−pipe system, which con-
sists of a return line that purges the fuel pump of air by return-
ing it to the tank. To determine the run and lift for piping, refer
to table 5 .
To determine the length of the run for piping, refer to table 4 .
Figure 17
Oil Piping Two-Pipe System
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fuel
pump
Aux
Filter
Return
pipe
Fill
Pipe
Air Vent
Oil
Tank
Inlet
Return
pipe
H
R
outside tank fuel pump above bottom of tank.
3"−4" (76 mm −102 mm)
