Lang RF21S-A, Service Manual, Page: 8 / 20

7
GENERAL
RANGE
The range is designed to give, well regulated, uniform heat throughout the oven and over the surface units.
The oven and surface units should be thoroughly preheated before being used. It is advantageous from an
operating cost stand point to operate with the switches and/or thermostats set at the lowest position that will
satisfactorily perform the cooking being done.
OVEN
The convection oven roasts and bakes in shorter time and at lower temperatures with less shrinkage than
conventional commercial ovens.
A blower in the Lang convection oven circulates air within the chamber to heat the entire space evenly and
transfer heat efficiently to the product, even with stacked loading.
The airflow continuously removes the thick layer of moist, cool air that otherwise would surround the product.
When properly loaded and operated, it maintains this airflow throughout the chamber to eliminate hot spots
and roasts or bakes with minimum power consumption at twice the output capacity of a conventional oven.
The power switch on the lower portion of the control panel energizes the fan motor and activates the
thermostatically controlled circuit for the oven heating elements. When this switch is in the on position, the
white bar indicator marked "power" will be illuminated.
Rotating the thermostat control knob from "off" position to selected temperature causes the red bar indicator
light to illuminate and closes the contactor that feeds power to the heating elements. This light will cycle "on
and off" as the thermostat calls for heat in the oven. The blower, however, operates continuously while the
power switch is in the "on" position.
The black control knob operates a damper in the oven vent stack. Damper is open when knob is pulled
outward.
Circuit breakers behind the control panel protect the electrical components from overload.
INITIAL PREHEAT
Prior to putting any range or oven into full time operation at normal cooking temperatures, it must be
thoroughly "seasoned" or dried out. Moisture absorption in the closed spaces, in the insulation and even inside
the heating elements can cause future trouble if not properly treated.
To "season" the convection oven, set the thermostat dial at 200°F and turn on the power switch. Allow unit to
cycle at least 15 minutes at this heat level. Reset the thermostat to 250°F allowing the same time. Then reset
the thermostat to 350°F. The oven should be operated at this heat level for a minimum of 4 hours preferably 5
hours, to insure the complete removal of all moisture.
If the unit is out of use for three or more days, a one hour preheat schedule should be used, especially when
exposed to high humidity and/or cool temperatures.