Bradford White 30S Installation & Operating Instruction Manual page 10

Oil tanks and Piping Continued-
D. Suction Line: It is recommended that extra heavy wall copper tubing
be used for this line. If standard wrought iron pipe is used. It should
be scale free and not smaller than 5/8" OD. Copper tubing should be
installed to connect the pipe to the fuel unit. Where tubing is used,
one complete loop should be made in the tubing to connect the pipe
to the fuel unit. Where tubing is used, one complete loop should be
made in the tubing immediately below the fitting connecting it to the oil
pump in order to reduce transmission of noise and to prevent strain
on the burner. When the top of the oil storage tank is below the level
of the fuel unit, high points or air pockets in the suction line must be
avoided between the oil storage tank and the fuel unit, and a 5/8" OD
ball check valve should be installed to prevent the return of the oil to
the oil storage tank during the off cycle period of the burner. Do not
run suction or return line overhead as this greatly increases the
possibility of air pockets, oil leaks, siphoning and transmission of
noise. When the top of the oil storage tank is above the fuel unit and
gravity feed to the unit is not permitted, the suction line should be run
to a point above the tank where an approved anti-siphon valve and a
5/8" OD gate valve shall be installed. These valves shall be installed
inside. No ball check valve is required, but a union should be installed
between the gate valve and the strainer to facilitate the removal of the
strainer for cleaning when necessary.
E. Return Line: The return line should be the same size as a suction
line and run as directly as possible from the return opening in the fuel
unit to the oil storage tank and should extend into the oil storage tank
to the same depth as the suction line.
F. Pressure Test for Buried Oil Lines: It is important that buried oil
lines be thoroughly tested for leaks before being covered.
CAUTION
DO NOT USE GASOLINE, CRANKCASE DRAININGS,
OR ANY OIL CONTAINING GASOLINE
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