American Water Heater GAS-FIRED COMMERCIAL WATER HEATER Test or Condition Result Action Taken

Index

Test or Condition:	Result:		Action Taken:
Start - Disconnect sensor	Is resistance between 700 and		Sensor(s) may be shortened
leads from electronic control	30K ohms (see page 38)?		or open. Check for loose,
module and measure	YES↓	NO→	broken or shorted wires.
resistance of sensor(s) with			Replace sensing bulb(s) if
ohmmeter			necessary.
Sensors O.K. Disconnect	Is water temperature greater		Replace sensing bulb with
ECO leads and measure	than 210°F (99°C) and ECO		ECO limit and check out
resistance with ohmmeter	resistance less than 10 ohms		balance of system.
	(shorted)?
	YES→	NO↓
Disconnect potentiometer	Is resistance greater than		Replace electronic control
leads from electronic control	4800 ohms at minimum		module. Reconnect all leads
module. Measure resistance	temperature setting (checks		and check out system
of potentiometer with	for short)?
ohmmeter.	YES↓	NO→
Potentiometer O.K.			Replace electronic control
			module. Reconnect all leads
			and check out system

If water temperature is too cold or heater does not come on, proceed as follows:

Test or Condition:		Result:		Action Taken:
Start: Check voltage at 24-volt		Is voltage between 21.5 and		Check power supply,
terminals of electronic control		28.5 VAC?		transformer. Correct as
module of thermostat board.		YES↓	NO→	necessary.
Are main burners operating or		Check for voltage at N.O.		Thermostat relay is not
is pilot trying to light		thermostat terminals (terminal		closing. Check thermostat
(sparking)?		to meter to ground). Is voltage		setting. Refer to thermostat
YES↓	NO→	between 21.5 and 28.5 VAC?		troubleshooting below.
		YES↓	NO→

Troubleshooting Procedure for Electronic Thermostat (continued)-

If water temperature is too cold or heater does not come on, proceed as follows:

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