Condensing Water Heater Service Manual 5 100000354
Diagnostic Codes
1. Water Flow Begins.
• Water Flow Sensor sends pulses to the PC
Board.
• PC Board senses flow.
• Firing Sequence begins when the flow exceeds
the minimum activation flow rate.
2. Firing Sequence.
• PC Board monitors water temperature,
temperature set point, and water flow rate.
• Combustion fan energized. Purges combustion
chamber.
• Spark igniter begins sparking.
• Gas control valve opens to minimum fire rate.
• Flame rod(s) proves ignition.
• Spark igniter stops sparking.
3. Normal Operation.
• PC Board monitors flame rod, fan motor
frequency, outlet water temperature, controller
temperature set point and water flow rate.
• Gas control valve modulates gas input to
required firing rate.
• Combustion fan speed is adjusted for the
required firing rate.
• Water flow control valve is adjusted as needed.
4. Shut-down Sequence.
• Shut-down begins when the PC Board senses
the minimum flow rate which is 0.26 - 0.5 gpm
depending on model.
• Gas control valve closes.
• Water flow control valve resets to standby
position.
• Combustion fan runs for a short period of time
at low speed.
5. Standby Mode.
• PC Board monitors water temperature and
remote controls.
• Freeze protection is activated as needed.
Operation
To display the most recent error codes press and hold the “On/Off” button for 2 seconds. While holding the “On/
Off” button press the ▲ button. The last 9 error codes will flash one after the other. To exit this mode press the
“On/Off” and ▲ button as before.
To enter or exit the maintenance monitor information mode, press and hold the button for 2 seconds and
without releasing it press the ON/OFF button.
To obtain the water flow rate: press the or buttons until “01” displays. The water flow rate will then appear.
For example “58” means 5.8 gal/min.
To obtain the outgoing water temperature press the or buttons until “02” displays. The temperature will
appear in degrees Fahrenheit.
Models MC-91-2 and MCC-91-2 (KB Series)
Data Unit No.
Water flow rate 0.1 gal/min 01
Outgoing water temperature Degrees Fahrenheit 02
To Next Page
Loading...
Need help?
General
