Normal Operation; Error Codes; Miscellaneous - Noritz NR50-OD Service Manual

< How to Use NR50-OD, NR66 (-SV,-OD) / N-0531S (-OD), NR71 (-SV,-OD) / N-0631S (-OD) >

1.Normal Operation

1. Turn the unit on. If an optional remote controller is not installed with the unit, the unit will be on as soon as
electricity is connected to it. If a remote controller is installed, the power button will need to be pushed to turn
the unit on.
2. Whenever a hot water fixture is opened, or an appliance that requires hot water is turned on, as soon as the
flow sensor detects at least the minimum flow rate required combustion, the fan will iniate and pre-purge any
residual combustibles in the combustion chamber. The igniter will then create a spark and the gas valves will
open allowing fuel into the combustion chamber where it be ignited by the spark.
3. When the flame rod detects a flame, the igniter will stop sparking.
4. The computer will then control the gas and water control valves to maintain the water at the temperature
setting. The temperature can be adjusted by removing the temperature jumpers, or by changing the remote
controller setting if one is installed.
5. When the demand for hot water ceases, the unit will stop heating.
When the flow sensor detects that the rate has dropped below the minimum rate for continued burning, the
gas valves will close and the burner flame will go out. After the post purge removes residual gas from
combustion chamber, the unit stops.
If necessary, turn off the power by either disconnecting the power supply, or pressing the power button on
the remote controller if one is installed.

2. Error Codes

The unit will indicate problems with a flashing light on the circuit board inside the unit that will be visible
outside the unit through a small window. If a remote controller is installed, it will display error codes as
follows.
If the flame rod does not detect a flame, or if the high limit switch has been triggered, the gas valves will
close, the flame will go out, and an error code will flash on the remote controller if one installed.
In order to reset the unit and remove the error code, turn the power off by either disconnecting the power
supply or by pressing the "operation button" on the optional remote controller, and then press it again to turn
the unit back on.
If the problem requires service (the thermal fuse is triggered,etc) the gas valve will stay closed and resetting
the unit will not eliminate the error code. If this is the case, the unit must be serviced before it will work again.

3. Miscellaneous

If the unit will not be used for a long period of time, turn off the power, drain the unit of water, and close the
manual gas valve on the supply line.
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