Sequence Of Operations - Rinnai RHFE-551FA Service Manual

1. The blower (combustion) motor fan starts and purges the combustion and heat exchanger
chambers making sure that they are clear. The green LED light is on.
2. The blower stages down and the ignition module powers the spark igniter and spark
occurs. When the spark is sensed as being correct, the PCB allows voltage to the
solenoid gas valves and gas enters the chamber. Ignition occurs and the flame rod begins
to prove flame. The blower motor stages back up to high. When the burner is on the LED
glows red indicating the burner is on. If the flame is correct and a secure ground is
available, then the flame rod produces micro-amps and the unit will fire trying to reach your
set room temperature.
3. The convection (room blower) will start on low speed circulating warm air into the structure.
After the PCB compares the set temperature to the room temperature, the seven stage gas
valve and fan control will fire the unit at the most efficient rate to obtain the comfort level as
set.
4. The negative co-efficient thermistor will sense the room temperature at the floor level and
will provide feedback to the PCB to determine the firing rate, fan speed, and run time.
When the set temperature is reached, the red indicator will return to green indicating the
burner is off. The convection fan will continue to run cooling the exchangers and
electronics for about 4 minutes.
5. The LED will be green indicating the unit is on standby. When the structure temperature
drops, the process starts over again.
6. Fresh air for combustion is drawn from outside and exhaust air is eliminated to the outside.
Moisture coming from the vent outside is normal as most high efficient units produce
moisture.
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Sequence of Operations

Rinnai Direct Vent Service Manual