Chapter 6 — Adjustment Procedures
6-26 Part No. 750-184
electrically removed from the circuit when a combination fuel
burner is fired on gas (Figure 6-18).
X. LOW-OIL-TEMPERATURE SWITCH
The L.O.T.S. prevents the burner from starting, or stops its
operation, if the temperature of the oil is below normal operating
temperature.
To adjust the control, insert a screwdriver into the center slot in the
control cover and turn the dial until the fixed (center) pointer is
approximately 30°F lower than the oil heater thermostat setting.
Turn the differential adjusting screw (located above dial) until the
movable indicator is approximately 5° F above the setting on the
main scale.
On a hot water boiler, the low-oil-temperature switch is an integral
part of the electric oil heater. The switch is non-adjustable and is
factory set at approximately 40° F below the maximum operating
temperature of the heater.
Y. HIGH-OIL-TEMPERATURE SWITCH
The H.O.T.S. prevents the burner from starting, or stops its
operation, if the temperature of the oil exceeds the normal operating
temperature.
To adjust, turn the dial until the pointer is approximately 25° F
above the normal operating temperature. The controls generally
have a set differential and will close 5° F below the setpoint.
Z. LOW OIL PRESSURE SWITCH
The L.O.P.S. prevents burner ignition, or stops its operation, when
the oil pressure is below the set point. Adjust the control by turning
the screw on top of control case to an indicated pressure 10 psi
below the established primary oil pressure setting indicated on the
oil supply pressure gauge. The switch will remain in a closed
position as long as the oil pressure exceeds this setting. The control
normally used automatically resets when pressure is restored after
a drop.
AA. ELECTRIC OIL HEATER THERMOSTAT (400 AND
600 SERIES - STEAM)
The maximum temperature setting of the control is stamped on the
dial. The maximum Temperature setting is attained with the
adjusting knob turned to the “high” end of the scale. Lower settings
are obtained by turning the adjusting knob clockwise using the
thermometer in the fuel oil controller as a guide.
The final setting of this thermostat should be at a temperature
approximately 15° F lower than the steam heater thermostat. This
eliminates the electric heater operation when the steam heater is
functioning. The electric heater is sized to provide sufficient heated
oil for low-fire operation on cold starts before steam is available.
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