Sequence Of Operation; Diagnostics - Detroit Radiant Products REV Series Installation Manual

4.0 Operation •

Sequence of Operation

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.
Sequence of Operation
Standby: The 35-66 control continually checks for internal faults, circuit integrity, and relay contact
positioning.
Starting Circuit: Upon a call for heat, the control verifies that the differential switch is in the proper position
(open). The control energizes the fan. Once operational static pressure is achieved, the differential
switch will close initiating the ignition sequence. The glo-bar is powered and the gas valve opens after
45 seconds. If the flame is not sensed, the heater will attempt to re-ignite for a total of three (3) trials for
ignition before proceeding to soft lockout.
Single Stage Running Circuit: After ignition, the flame rod monitors burner flame. If sense of flame is lost, the
control closes the gas valve within one second and a new trial sequence (identical to the starting
sequence) is initiated. 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.
Two Stage Running Circuit: The second stage on the gas valve is powered directly from the second stage of
the thermostat. In order for two stage to flow to a higher output, single stage must be energized as well.
The thermostat determines which stage to maintain for the desired temperature.
Shut Down: When the thermostat is satisfied, the fan will enter a two (2) minute post-purge cycle. Refer to
Soft Lockout and Hard Lockout under Diagnostics below.

Diagnostics

Lockout: The controls will automatically lockout the heater system when an external or system fault occurs.
There are two types of lockout:
Soft Lockout: The heater will attempt to light three times. In the event of a failed attempt to light, (gas
pressure, valve, no flame sense etc.), the heater will enter a soft lockout period for 15
minutes and then attempt to light three more times before entering Hard Lockout mode.
Hard Lockout: If proof of flame is not established, a component failure occurs or blockages are evident, the
heater will enter hard lockout. If lockout occurs, the control can be reset by briefly
interrupting the power source. Refer to Charts 4.1 and 4.2 on page 55 for a description of
LED codes.
Externally located operational indicator lights are provided to assist in troubleshooting of the heater. Refer to
page 56 for additional troubleshooting.
WARNING
!
54
REV Series