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Checking for
a Crossed
Connec on
1. Turn off cold water supply valve
to the water heater. If there are
pumps installed in the system for
recirculation, ensure that they are
turned off.
2. Turn on hot water at one fixture in
the structure. If possible, use the
hot side of a two-handle fixture.
If you must use a single-handle
fixture, make sure that it is open to
the hot side only.
•
After a brief time, the water
should drain completely.
•
If water continues to run, the
fixtures and plumbing system
need to be checked.
•
Cold water cross-connections
may be related to a recirculation
pump application, a defective
mixing valve, a bad check valve,
a missing check valve in the
application, or a cartridge in a
single-handle faucet that needs
to be replaced.
Checking for
a Reversed
Connec on
1. Close cold water supply at the inlet
and pump return connections.
2. Open the pressure-relief valve or
the hot water tap of a two handle
faucet.
3. If water continues to run through
the pressure-relief valve or hot
30
•
On-Demand Water Heater Service Handbook for X3P Models
water faucet, the system has a
reversed connection.
Checking the Inlet
Gas Pressure and
Pressure Drop
This test is most effective when all gas
appliances on the supply line are operating.
1. Close the manual shut off valve at
the gas supply line inlet.
2. Open a hot water fixture. The unit
should turn on and the remaining
gas in the pipe line should purge
out. Close the water fixture
when the flame in the heater
extinguishes.
3. Turn power to the heater off by
unplugging it or closing the external
shutoff switch.
4. Remove the screw from the
pressure port located on the gas
inlet. See Figure 10.
Pressure port
Figure 10: Pressure port location.
5. Connect a manometer to the pressure
port and zero the manometer.
6. Slowly re-open the manual gas
valve. Confirm that there are no gas
leaks.
7. Turn power to the water heater on.
8. Open some of the hot water
fixtures that use the highest flow
rate to turn on the unit. Once the
heater has reached a steady firing
rate, press and hold the "MAX"
button on the computer board.
(See Figure 11).
INCREASE
DECREASE
Figure 11: Max button on computer board.
9. Record your gas supply pressure
(dynamic).
10. Release the "MAX" button and
close all of the water fixtures.
11. Record your gas supply pressure (static).
12. The gas supply pressures should be
within the following ranges:
•
Natural Gas: 3.5 to 10.5 inches W.C.
•
Propane: 8 to 13.0 inches W.C.
13. Subtract your dynamic supply gas
pressure (step 9) from your static
supply gas pressure (step 11). This will
be your pressure drop.
14. If the pressure drop is more
than 1.5 inch W.C., there may be
insufficient gas supply, incorrectly
sized gas line, or incorrectly sized
gas regulator. NOTICE: In Canada,
do not exceed the maximum
allowable pressure drop permitted
by B149.1.
15. Remove the manometer.
16. Install the screw into the gas pressure
port on the gas inlet (hand tight).
WARNING! Ensure that there are
no gas leaks. Failure to prevent gas
leaks can result in an explosion,
severe injury, or death.
17. Turn power to the water heater on.
MAX
MIN
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