Measuring Inlet Gas Pressure - American Water Heater 240HX3 Installation Manual And Owner's Manual

1. Turn off all electric power to the water heater if service is to be performed.
2. Turn the manual gas valve located on the outside of the unit to the off position.
3. Failure to follow these steps could lead to fire or explosion, resulting in personal injury or
death.
WARNING
The water heater cannot perform properly without sufficient inlet gas pressure. Below are instructions on how
to check the inlet gas pressure. ONLY A LICENSED PROFESSIONAL SHOULD PERFORM THE PROCEDURE BELOW.
Shut off the manual gas valve on the gas supply line.
1.
Remove the screw from the pressure port which is located on the gas inlet of
2.
the water heater shown in the diagram on the right.
Connect the manometer to the pressure port and zero the manometer.
3.
Re-open the manual gas valve. Verify that there are no gas leaks.
4.
With all gas burning equipment off, take a reading of the static gas pressure
5.
and make a note of it.
Measure gas supply pressure at maximum heater operation: Open hot water
6.
faucets to create maximum flow. Press the MAX button on the computer
board. (Refer to the diagrams below.) Take a reading of the supply dynamic
gas pressure with all gas burning equipment running at maximum rate.
The static and dynamic pressures should be within the ranges specified on the
7.
heater's rating plate and the table on page 30.
The difference of static to dynamic pressure should not exceed 1.5" W.C. Pressure drops that exceed 1.5"
8.
W.C. can indicate restricted gas flow, undersized gas lines, and/or undersized supply regulators.
Measure gas supply pressure at minimum heater operation: Reduce water flow so the heater is running at
9.
minimal operation. Press the MIN button on the computer board. (Refer to the diagrams below.) Take a
supply gas pressure reading and verify that it is within the specified inlet gas pressure range.
MAX button
MIN button

MEASURING INLET GAS PRESSURE

240HX3/340HX3
51
Maintenance and service
540HX3
MIN button
MAX button
Page
Owner's Guide
Pressure
port