How To Use; Normal Operation; Error Codes; Miscellaneous - Noritz NR501-OD Service Manual

< How to Use >

1.Normal Operation

(Hot Water Production)
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.
*When electrical power is connected to the unit, the Set Temperature is displayed for
approx. 3 minutes on the Display Window.
- 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 DIP switches on the Display
Window circuit board, 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

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 Display Window or the Optional 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 "POWER" 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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