Checking For A Crossed Connection; Checking For A Reversed Connection; Checking Inlet Gas Pressure/Purging Air From Gas Line; Checking And Adjusting The Manifold Gas Pressure - A.O. Smith ATI-140H-N Service Handbook

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 all hot water fixtures.
•
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.
2. Open the pressure-relief valve.
It should be installed on the hot
outlet side of the unit.
3. If water continues to run through
the pressure-relief valve, the
system has a reversed connection.
Checking Inlet Gas
Pressure/Purging
Air from Gas Line
1. Close the manual shut off valve at
the gas supply line inlet.
2. Open a faucet. The unit should
turn on and the gas in the pipe
line should purge. Leave the faucet
on to keep the unit running until
it shuts down due to lack of gas,
then shut the faucet off. Ignore any
error codes that may occur at this
time.
Gas Supply
Pressure Port
Figure 13.
Condensing Models: On-Demand Water Heater Service Handbook • 25
3. Remove the screw for the pressure
port located on the gas inlet. See
Figure 13.
4. Connect a manometer to the
pressure port.
5. Slowly re-open the manual gas
valve. Check to see that there are
no gas leaks.
6. Open some of the fixtures that
use the highest flow rate to turn
on the unit. Ensure that the water
heater is running at maximum fire
by pressing and holding the "MAX"
button on the computer board. (See
Figure 8, page 18).
7. Check the inlet gas pressure.
Appropriate pressures are as
follows:
•
Natural gas:
5 – 10.5 inches W.C.
•
Propane:
8 – 14.0 inches W.C.
Checking and
Adjus ng the
Manifold Gas
Pressure
WARNING! Complete the following
procedures ONLY if you have been
instructed to do so by the Technical
Service Department.
Adjusting the manifold pressure can
cause unexpected combustion
conditions during operation, which can
cause a health hazard, damage to the
water heater, and/or shorten its
lifespan. Therefore, changing the
manifold pressure is not
recommended unless there are very