Operation; Sequence Of Operation - Re-Verber-Ray MP3 Series 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 three (3) main control devices for the MP3 Series heater.
• The TH-PC-M (or other compatible) thermostat sends a 24 VAC signal to the heater to enable the unit to
call for heat, and a 0–10 VDC signal to modulate the heater based on demand.
• The TP-351A ignition controller is responsible for the ignition sequence, flame monitoring, and safety
lockout features.
• The TP-3250A modulating controller is responsible for the modulation of the fan speed which
pneumatically modulates the gas valve based on pressure.
Starting Circuit:
The power cord supplies 120 V at all times to an internal transformer and TP-3250A modulating controller.
The transformer directs power via a blue (+24 VAC) wire and yellow (-24 VAC) wire to supply power to the
thermostat.
Upon a call for heat, the thermostat will send two signals out. First, +24 V will be sent to the red wire of the
control input on the heater. This is for the enable relay and will energize the TP-351A ignition module. Second,
the thermostat will send a 0–10 VDC through the brown (-) and gray (+) wires going to the control input of the
unit. The TP-3250A awaits a 0–10 VDC signal to initiate fan control. Once a signal is received, the TP-3250A
sends voltage to the fan based on demand (1 VDC being the lowest and 10 VDC being the highest demand).
The fan will pressurize the air chamber being monitored by the normally open (N.O.) pressure switch. Once
pressure has been achieved, voltage will be routed to the normally closed (N.C.) pressure switch responsible
for monitoring blockages in the exhaust. If no blockages are present, the N.C. switch will stay closed and
direct power back to the ignition module, initiating the next sequence.
The ignition board will send 120 VAC to the glo-bar for approximately 45 seconds after which the ignition
board will send 120 V to the gas valve relay coil. When the ignition board detects flame, the igniter is
deactivated and the gas valve relay coil remains powered, closing the relay and directing 24 VAC to the gas
valve. Flame should now be present on the burner and visible through the sight glass.
Running Circuit:
At this point, the TP-351A will use the flame rod to sense flame. Flame rectification can be measured in micro
amps at the flame current test pins on the TP-351A).
WARNING
!
12
MP3 Series