A.O. Smith PCG2J4040T3NOV 100 Checking the GAS Supply Pressure, Checking the Gas Supply Pressure

23.Turn on the gas supply to the unit and test the gas supply line and union connections by brushing on an approved noncorrosive leak detection solution (Figure 116).

24.Turn on the electrical and the gas supplies to the water heater. Plug in the electric connection from the transformer to the electric outlet (Figure 113).

25.Restart the water heater by following the directions on the “Lighting and Operating Instructions” label located on the front of the water heater .

26.As the burner is heating (view flames through viewport), test the manifold tube connection at the gas control valve/thermostat by brushing on an approved noncorrosive leak detection solution (IMPORTANT: Do Not splash any solution onto any electrical connections) (Figure 120).

27.Upon verifying proper operation of the water heater, replace the manifold cover/outer door.

Figure 120.

IMPORTANT:
WHEN BRUSHING ON AN		GAS CONTROL
APPROVED NONCORROSIVE
LEAK DETECTION SOLUTION,		VALVE/THERMOSTAT
DO NOT SPLASH SOLUTION
ONTO ELECTRICAL CON-
NECTIONS.
		PRESSURE
MANIFOLD TUBE		SWITCH/FAN,
		FV SENSOR
POWER SUPPLY	IGNITER/	CONNECTOR
TRANSFORMER	FLAME
CONNECTOR	SENSE	DISPLAY, ANODE
	CONNECTOR	ROD CONNECTOR

CHECKING THE GAS SUPPLY PRESSURE

Checking the Gas Supply Pressure

Gas pressure checks are done with flowing gas using a gas pressure gauge capable of reading pressure in inches of water column.

•Supply gas pressure checks are measured before the gas control valve/thermostat and as close to the water heater as possible.

•Manifold (main burner) gas pressure is measured at the pressure tap on the side of the gas control valve/thermostat. Use an allen wrench to remove the plug then attach the gas gauge.

	GAS CONTROL
GAS CONTROL	VALVE/
	THERMOSTAT
VALVE/
THERMOSTAT
USE AN ALLEN
WRENCH TO REMOVE
AND REPLACE PLUG.
MANIFOLD GAS PRESSURE TEST	GAS
	PRESSURE
CONNECTED AT	GAUGE
PRESSURE TAP
SUPPLY GAS PRESSURE TEST

NOTE: Desired gas pressures will be noted on	Figure 121
the gas valve label located on the gas control
valve/thermostat.

IF . . .		. . . THEN
supply gas pressure is under desired pressure		• increase supply gas pressure regulator setting
requirement		and,
		• increase supply gas piping size.
supply gas pressure is over desired pressure		• add gas pressure regulator.
		• reduce setting on existing regulator.
manifold gas pressure is more than +/- .3 inch		• ensure there is adequate supply gas pressure
W.C. from values indicated on gas valve		• ensure the main burner orifice is the correct size
		for the water heater model being tested.
		• if the above tests have been performed and the
		results were correct replace the gas control valve.
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