Adjustment Procedures
6-28
750-91 (revised 2009)
Model CB-LE Packaged Boiler Manual
6.28 — Steam Oil Heater Thermostat: No. 6 Oil (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 the thermostat should provide oil at a sufficient temperature for efficient combustion based on
flue gas analysis. There is no need to heat the oil in excess of the temperature.
6.29 — Hot Water Oil Heater Thermostat (400 and 600 Series)
To adjust the thermostat, insert a screwdriver into the center slot in the control cover and turn the dial until the
pointer is at the desired temperature level. The control generally has a set differential, and will close 5º F below the
setpoint.
The thermostat contacts close to energize the booster water pump, which pumps water from the boiler through the
heater. On cold starts, it is normal practice to manually close the valve in the pump discharge line until the boiler
water temperature exceeds the temperature of fuel oil entering the heater.
The electric oil heater on a hot water boiler burning No. 6 oil and equipped with a hot water oil heater has a built-
in adjustable thermostat. The maximum temperature setting is stamped on its dial. The desired temperature can be
obtained by turning the adjusting screw. The thermostat should be set at a temperature approximately 15 degrees
lower than the hot water heater thermostat. Such a temperature prevents the electric heater from operation when
the water heater is functioning. The electric heater is sized to provide sufficient heated oil for low-fire operation on
cold starts before hot water is available.
6.30 — Steam Heater Pressure Regulator (400 and 600 Series: Steam)
The regulator is provided on a boiler designed to operate at pressures above 15 psi and reduces boiler steam pres-
sure to the level necessary for proper operation of the steam oil heater. The pressure should be reduced to a point
that permits sufficient temperature to heat the oil, while allowing as continuous a steam flow as possible. Pressure
that is too high will result in frequent cycling of the steam solenoid valve.
It is best to adjust the regulator under typical flow conditions. To do so, it is suggested that the globe valve in the
steam supply line be closed so that there is no pressure on the regulator. Turn out the adjusting screw fully to
relieve compression on the regulator spring, thus closing the regulator. With steam at normal pressure, open the
globe valve and then set the secondary pressure by turning the adjusting screw or handle until the downstream
gauge shows the desired pressure.
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