Gas Pressure Test - State Water Heaters 60120-100250 Service Handbook

5. When installing multiple water heaters in the same gas supply system it is recommended that individual
positive lock-up gas pressure regulators be installed at each unit from the supply gas connection on
the water heater.
Service notes:
• The manifold gas pressure is factory set and cannot be adjusted in the field.
• There are two pressure test ports on the water heater's 24 Volt Gas Control Valve, see Figure below. The
Gas Control Valve outlet pressure test port is closest to the Combustion Blower, see Figure below. There
is a needle valve in each test port that is opened/closed with a small slotted screwdriver. Turn the needle
valve counter-clockwise to open the test port valve and clockwise to close it.
• The hose from the Gas Control Valve supply gas pressure test port should be connected to the positive
pressure port of a manometer; the other pressure port of a manometer should be left open.
• There is usually a drop in supply gas pressure noticed when the water heater's 24 Volt Gas Control
Valve opens during ignition. The manifold pressure will go from a negative value (during pre-purge) to
near zero when gas is flowing.
• A sustained drop in supply gas pressure of 1.5" W.C. or more during ignition may indicate the supply
gas line is undersized. If the water heater is experiencing a sustained drop in supply gas pressure of
1.5" W.C. or more and the water heater is experiencing repeated Ignition Failure fault conditions,
intermittent loss of flame or rough starting ensure the supply gas line is sized in accordance with the
current edition of National Fuel Gas Code (ANSI Z223.1/NFPA 54) or the Natural Gas and Propane
Installation Code (CAN/CSA B149.1).

GAS PRESSURE TEST

1. Use the Enable/Disable Switch located on the front of the water heater and put the unit in disabled mode.
2. Turn off the supply gas to the water heater at the main gas shutoff valve serving the water heater.
3. Open the Supply Gas Pressure Test Port on the Gas Control Valve, see Figures below. Turn the needle
valve slotted head 1/2 to 1 full turn counter-clockwise with a small slotted screwdriver to open the valve.
4. A digital manometer (see "Tools Recommended" on Page 2) is needed to check supply gas pressure. To
monitor supply gas pressure, attach a sensing tube from Gas Control Valve Supply Gas Pressure Test
Port to one digital manometer.
5. Open the main gas shutoff valve serving the water heater.
6. The manometer connected to the Supply Gas Pressure Test Port should read the "static" (gas is not
flowing) supply gas pressure.
MANIFOLD GAS
PRESSURE
TEST PORT
COMBUSTION
BLOWER
CONNECTION
SUF 60120 - 100250 Models
SUPPLY GAS
PRESSURE
TEST PORT
GAS CONTROL
VALVE
COMBUSTION
AIR INLET
VENTURI
Servicing should only be performed by a Qualified Service Technician
AIR INTAKE PRESSURE
REFERENCE CONNECTION
MANIFOLD GAS
PRESSURE
TEST PORT
SUF 119300 - 119500 Models
SUPPLY GAS
PRESSURE
TEST PORT
9