Figure 2-9. Control Panel. Heating Mode.
If the burner does not ignite within 15 seconds after switch S1 has been placed into the HEAT
position or if burner goes out during heating mode, the SAFETY RELEASE light (2) will come on
and the audible alarm EMI (7) will sound. To restart unit switch S1 back into VENT position,
depress RESET (I), and repeat steps 5, 6, and 7. If unit fails to operate properly, proceed to
(9) When operating in recirculating mode, adjust fresh air damper opening for the desired amount of fresh air.
The temperature of air leaving the heater minus the temperature of air entering is called the
temperature difference (TD). The TD varies with the temperature of air entering the heater, and
can range from 70 to 145° Fahrenheit (F). For ambient air 20-50° F, the TD is usually 75-85° F.
For ambient air over 50 the TD is usually 85-95° F. The greater the TD, the more quickly the
desired temperature will be reached;
(10) Set the return air control knob at the actual enclosure temperature. Set the supply air control knob at the
desired enclosure temperature.
Change 2 2-21