Operation - Re-Verber-Ray MP-25-80N Insert Manual

3.0 Operation • Sequence of Operation
3.0

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.
Note: Reference the Tube Heater General Manual for installation requirements.
Sequence of Operation
There are two (2) main controllers for the MP Series heater. The TP-351A is the ignition controller, and is
responsible for the ignition sequence, flame monitoring, and safety lock-out features. The TP-3250 is the
modulating controller, and is responsible for the call for heat, modulating the gas valve and blower speed,
selecting the performance curve or mode, and handles various passive inputs and outputs for controlling
devices. These two devices will be referred to as their TP-#'s during the sequence of operation.
Standby:
TP-351A - 120VAC is held at the circuit of the circuit board.
TP-3250 - 24VAC and 120VAC is held at the circuit board.
Starting Circuit:
The TP-3250 checks various inputs to select the performance curve, model, and appropriate mode of
operation. After successful determination of all internal checks, the TP-3250 will output the conditioned
120VAC to the blower motor and 120VAC to the common side of the pressure switch.
Once operational static pressure is achieved, the differential switch will close, sending the 120VAC to the
TP-351A and the PS indicator light, initiating the ignition sequence. The glo-bar is energized with 120VAC
for 45 seconds from the TP-351A. Once the time is achieved, the TP-351A switches on the 120VAC for the
valve circuit and switches off the power to the glo-bar. The 120VAC from the TP-351A valve circuit is used
to power the coil side of the isolation relay and sends power to the TP-3250 to indicate the start of the
ignition sequence. The isolation relay switches 24VAC from the transformer to the primary coil of the gas
valve and valve indicator light.
Once the gas valve circuit is energized from the TP-351A, flame should be present on the burner and
visible through the sight glass. The flame rod monitors the burner flame through flame rectification, and
can be measured in micro-amps (this can be verified at the flame current test pins on the TP-351A).
Minimum required micro-amps are 1.0mA, and should be present during burner operation.
If the burner fails to light or flame is not detected within 8 seconds, the gas valve circuit is de-energized
and the control performs an "inter-purge" delay before attempting another ignition sequence. The control
will attempt 2 additional trials of ignition before entering the soft lock out sequence. In the soft lockout
sequence, the gas valve will be turned off immediately. After 1 hour, if the thermostat is still calling for
heat, the TP-351A will automatically reset and attempt a new trial for ignition. After multiple attempts to
ignite the burner have failed, the TP-351A enters a hard lockout mode. The control will not open the gas
valve unless there is an intervention by the user. The reset can be done by either resetting the thermostat
or removing the 120 VAC for a period of 5 seconds.
WARNING
!
18
MP Series