The Electronic Thermostat, Diagnostic LED Light

The Electronic Thermostat

IMPORTANT: The Energy Smart® Module (ESM) must be removed before attempting to access the thermostat. NOTE: for the Electronic Thermostat (ET) changes to re- main in effect the Energy Smart® Module (ESM) must not be reconnected, also read the “Water Temperature Regu- lation” under the “Operating Your Water Heater” section. If the instructions are not clear, contact a qualiﬁed person.

The Energy Smart® Module (ESM) is intended to serve as the primary interface for operating the water heater; however, the Electronic Thermostat (ET) may control the water heater in the absence of the Energy Smart® Module (ESM).

The Electronic Thermostat consists of an electronics box that contains a low voltage power supply, the thermostat set point knob, relays to switch between the upper and lower heating elements, one control thermistor, a connec- tor for the lower element control thermistor, microelectron- ics to convert the thermistor signals and perform switch- ing and other logic functions, and a connector to tie the Electronic Thermostat (ET) to the Energy Smart® Module (ESM) located on the front of the water heater jacket. The majority of the self-diagnostics are located in the Electronic Thermostat (ET), including the dry-ﬁre protection intelli- gence. The thermostat circuit is designed so that when the upper heating element calls for heat, the power is directed to that element even if the lower element is also calling for heat.

Diagnostic LED Light

The Green/Red LED light indicates the status of the elec- tronic thermostat (See Figure 10A).

•Green LED will signal normal operation. The green LED will blink 2 times per second to indicate that power is applied to the upper heating element and at a faster rate (4 times per second) to indicate that the lower heating ele- ment is powered.

•Red LED will ﬂash error codes. If a fault is detected by the electronic thermostat, the LED light indicator will use the red LED to indicate the fault detected. The ﬂash code sequence is to consist of 1/2 second ﬂashes of the red LED each separated by a 1/2 second off period.

The number of ﬂashes indicates the fault code number. (See diagnostic code chart section in this manual).

After the last 1/2 second “on” period, the LED will remain off until a total of 5 seconds has elapsed for the fault in- dication cycle (there is a 5 seconds delay before the fault ﬂash pattern repeats). After the 5 seconds are completed, the fault indication cycle is repeated starting with the ﬁrst 1/2 second-ﬂash. The ﬂash sequence will be repeated as long as the fault remains. Only one fault can be declared at a time. NOTE: the green LED is turned off when a fault code is being displayed, even though the heater may be operating in limp mode with an element on. See diagnos- tic code chart section in this manual.

Overriding The Energy Smart® Module (ESM)

If the Energy Smart® Module (ESM) is not working, simply unplug the interface module and turn the set point knob on the Electronic Thermostat (ET) to the desired tempera- ture (See Figures 10A & 10B). To replace a broken or damaged ESM module, see page 22 for ordering informa-

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