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overheating during maximum
burn. If presence of a gas leak is
detected, immediately shut off the
unit and inspect the tube/manifold
connection. Otherwise, proceed to
the next step
5. Press and hold down the "MIN"
button on the computer board. See
Figure 13.
Use the T15 Torx
TM
driver to adjust
the manifold pressure. Turning
clockwise increases pressure and
counter-clockwise decreases the
pressure. Use the manometer to
verify that pressure has been set to
the desired value.
6. When you are finished, turn off
water flow and then turn off power
to the water heater.
7. Shut off the gas supply to the
water heater at the manual gas
shutoff valve, before removing the
manometer tube.
8. After the gas pressure has been
set, remove the manometer tube,
and re-install the manifold port
screw and adjusting port cover. See
Figure 12.
9. Turn power to the water heater
on, then turn on the gas supply to
the water heater at the manual gas
shutoff valve.
10. Verify proper operation.
Checking the
Overheat Cutoff
Fuse (OHCF)
WARNING
1.
Disconnect electrical power from
the water heater before servicing.
Failure to do so can result in
electrical shock.
32
•
On-Demand Water Heater Service Handbook for X3P Models
2. Locate the white OHCF which wraps
around the heat exchanger (See Figure
14).
(Blue)
Figure 14: Overheat cutoff.
3. Find the white clip at the end of
the two blue braided wires coming
from the OHCF.
4. Unplug the connection.
5. Test resistance at the end of the
OHCF with a digital volt/ohm meter.
Resistance should measure 1 ohm
or less. Reconnect the plug.
If the resistance exceeds 1 ohm,
replace the OHCF. Replacing this
part will require you to remove
the heat exchanger. Follow the
"Replacing the Heat Exchanger"
instructions which are found in
the "Service Procedures" section.
Inspect the heat exchanger for any
burn marks, hot spots, cracks, etc.
6. Restore power and test the unit.
Checking the Flow
Sensor
Tools and Materials:
●
Flashlight
●
Towels
The flow sensor (item 402, p. 73)
is part of the flow control valve and
located above the X3 Manifold. Its flow
rate is determined by an impeller that
spins as water runs through it.
To check the flow sensor,
1. You can check the flow rate by
turning on power to the water
heater. Push the "Info" button on
the built-in controller three times.
This will display flow if the flow
sensor is working properly.
2. Turn off cold water supply valve to
the water heater.
3. Remove the flow sensor #402
as described in "Removing and
Replacing the Water Piping System
Components", page 61.
4. Blow into the inlet of the flow
sensor. Watch to see if the impeller
spins. It should spin freely for a few
seconds. If it comes to rest abruptly
or doesn't spin at all, it should be
inspected for blockage.
NOTICE: Do not try to disassemble
the flow sensor. If there is debris
that cannot be removed, or if the
impeller does not move freely,
replace the flow sensor/flow
control valve.
5. Reinstall the flow sensor as described
in "Removing and Replacing the
Water Piping System Components",
page 61.
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