Detroit Radiant Products Company DX3 Series - Manual (Page 12)

WARNING
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3.0 DX3 Series Operation • Sequence of Operation • Thermostat • Diagnostics
3.0 Operation
Note: Reference the Tube Heater General Manual for installation requirements.
Sequence of Operation
Starting Circuit: Upon a call for heat, the fan is energized. Once operational static pressure is achieved,
the differential switch will close initiating the ignition sequence. After a 5-second delay, the glo-bar is
energized for 45 seconds and the control allows the gas valve to open.
The trial for ignition is 8 seconds. If flame sense is not established within 8.5 seconds, the heater will
attempt two (2) additional ignition sequences before proceeding to soft lockout. Soft lockout
automatically retries after one (1) hour or the control can be reset by briefly interrupting the power
source.
Running Circuit: After ignition, the flame rod monitors burner flame. If sense of flame is lost, the control
immediately acts to reignite the gas-air mixture (identical to the starting sequence). If flame sense is
not established within 8.5 seconds, the heater will attempt two (2) additional ignition sequences
before proceeding to soft lockout. The control can be reset by briefly interrupting the power source.
Thermostat
NOTE: Different thermostats operate according to their particular features. Refer to thermostat
specifications for details. Refer to Figure 2.1 for field wiring diagrams.
DX3 Series heaters with 24VAO option require a 24VAC, single-stage thermostat to operate. The burner
control box is equipped with a round terminal strip that accepts two (2) 1/4” female spade terminals. Do
not supply 120VAC to the 24VAC connection.
This heater must be installed and serviced by trained gas installation and service
personnel only.
Do not bypass any safety features or the heater’s built in safety mechanisms will be
compromised.
DX3 Series