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SECTION 7
Trouble Shooting
7.1 Diagnostics
Question
Answer
Burner does not ignite
when the hot water is
opened.
Make sure that the ON/OFF button on the Control Panel has been turned ON.
If the monitor on the Control Panel is blank, make sure the power cord is
plugged and 4A fuses on the main controller in the units are good.
Make sure that there is water supplied to the unit. The unit activates once
the inlet water flow is over 0 gpm.
Make sure the cold and hot water lines are not plumbed in reverse side.
Make sure that the cold water and gas supply lines are opened.
Make sure that the water lines are not frozen.
Water is not hot enough.
Check that the setting temperature on the unit is not too low
Make sure that the filter in the cold water supply line is not clogged with debris.
Make sure that the gas supply type is correct.
Check the supply and manifold gas pressures are in accordance with specifications.
Make sure that the water flow sensor with three wires has been properly
connected on the top of heat exchanger.
Water is too hot.
Make sure that the setting temperature on the unit is not too hot.
Make sure that the filter in the cold water supply line is not clogged with debris.
Make sure that the gas supply type is correct.
Hot water temperature
fluctuates at the opened
tap.
Make sure that the filter in the cold water supply line is clean.
Make sure that the gas supply type is correct.
Check the supply gas pressure is sufficient.
The blower is still
operating after the
combustion stops.
This is normal because the blower keeps operating for 1 minute to
vent (exhaust) the flue gas from the chamber once the combustion has
stopped.
Temperature Rise
too Quickly
Occurs when supply water temperature in heat exchanger rises faster
than 2°F per second during the first two minutes the burner is on.
Automatically resets after a few minute delay or using manual reset on
control panel. See message displayed TEMPERATURE SENSOR and
follow procedure for loose connections.
Abnormal sounds come
from unit during operation.
A leak of combustion gas between sealed chamber and exhaust tube
inside the unit. Call a qualified service technician for evaluation.
Improper venting termination, make sure that the venting termination
complies with specification.
Check the supply gas pressure is sufficient. Insufficient gas pressure will
cause unstable burner flame and noise.
Heater doesn’t fire when
DHW flow is initiated
Domestic water flow may be too low. Min allowable is 0.75 gpm. Check
in Manual Mode OTO AGA
CH Temp drops lower
than expected before unit
re-fires
Change Parameter 14:bo to 10degrees F (5.5 degrees C)
