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Fault Isolation
Some of the checks below may need to be done by a qualified service technician. Call a
service technician for any remedy that involves gas or electricity. Call a service
technician if you have any doubt or reservation about performing the remedy yourself.
WARNING
Accessing
Operating
Information
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 display the water flow through the water heater press and hold the
▲
button for 2 seconds and without
releasing the
▲
button press the “On/Off” button.
To display the outlet water temperature press and hold the
▼
button for 2 seconds and without releasing the
▼
button press the “On/Off” button.
Standard and Commercial Controllers
1. Water
Flow
Begins.
•
Water Flow Sensor sends pulses to the PC
Board.
•
PC Board senses flow greater than 0.6 GPM
(approximate).
•
Firing Sequence begins.
2. Firing
Sequence.
•
PC Board monitors inlet/outlet 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 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.
•
PC Board senses flow rate less than 0.5 gpm
(approximate).
•
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
On-Demand Gas Tankless Water Heater Service Manual
10
The On-Demand water heater has the ability to check its own operation continuously. If a fault occurs, an error
code will flash on the display of the remote controller. This assists with diagnosing the fault and may enable
you to overcome a problem without a service call.