Starting and Operating Instructions
5-6
750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
If the oil supply tank is located above the level of the pump and flow to the pump is by gravity, then it will usually
be necessary to vent the suction line to allow oil to fill the line. Venting the suction line can generally be accom-
plished by cracking a union fitting, or by opening the cap of the oil strainer using care to prevent spillage of oil.
Tighten the fitting or the cap as soon as oil flow appears.
If the oil supply tank is below the level of the oil pump, it is mandatory that the suction line to the pump be com-
pletely filled with oil prior to starting the pump to avoid the possibility of damage to the pump gears. Non-lubricat-
ing fluids such as kerosene should not be used for priming.
Prior to priming the suction line and the initial start, check to make certain that all plugs, connections, etc., have
been securely tightened to prevent leaks.
If the fuel oil supply originates from a pressurized loop, it is assumed that the pressure of the loop will be at a min-
imum of 75 psi. Under these conditions, the relief valve at the terminal block should be adjusted to the point where
it becomes inoperative (or removed and openings plugged). To render inoperative, turn the adjusting screw in as far
as possible.
A standard equipped boiler has a selector switch incorporated in the oil pump motor starter. Momentarily energize
the starter to check for proper pump rotation. With the rotation verified, operate the pump to determine that oil
circulation exists. Observe the oil burner pressure gauge for indication that flow is established. If no pressure
shows on the gauge after a few moments, stop the oil pump and re-prime. If the supply tank is lower than the
pump, it is possible that the initial priming of the suction line, followed by operation of the pump, will not establish
oil flow. This might be caused by obstruction in the suction line, excessive lift, inadequate priming, suction line
leaks, etc. If oil flow is not readily established, avoid prolonged operation of the pump to minimize risk of damage
to internal parts of the pump. If oil flow is not established after a second or third priming attempt, a full investiga-
tion is required to determine the cause.
A vacuum (or a compound pressure-vacuum) gauge should be installed at the suction port of the pump and its
reading observed and recorded for future guidance. If a vacuum condition exists, the reading will reveal the tight-
ness of the system. It is advisable to maintain the vacuum reading at less than 10” Hg. A vacuum in excess off 10”
Hg may allow oil to vaporize, causing cavitation, loss of prime, and an unstable firing condition.
Oil supply pressure is regulated by adjusting the pressure relief
valve at the oil terminal block. A pressure gauge should be installed
in the terminal block and the relief valve adjusted to obtain a mini-
mum reading of 75 psi when the burner is firing at maximum rate.
FIGURE 5-6. Oil Terminal Block
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