ELECTRICAL DATA
General
Check the water heater model and rating plate information against the characteristics of the branch circuit electrical supply. Do not connect the heater to an improper source of electricity.
Voltage applied to the water heater should not vary more than +5% to
Do NOT energize the branch circuit for any reason before the water heater tank is filled with water. Doing so may cause the heating elements to fail.
The installation must conform to these instructions and the local code authority having jurisdiction. Grounding and electrical wiring connected to the water heater must also conform to the National Electrical Code, NFPA 70. This publication is available from The National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02269.
Branch Circuit
The branch circuit wire size should be established through reference to the NEC (National Electrical Code) or other locally approved sources in conjunction with the water heater amperage rating.. Wire rated at 75°C should be used. For convenience, portions of the wire size tables from the Code are reproduced in Table 1 on page 9. It is suggested the electrician size the branch circuit at 125 percent of the heater rating and further increase wire size as necessary to compensate for voltage drop in long runs. Voltage drop should not exceed 3% at the water heater.
Heater Circuits
The water heater’s electrical components are pictured and identified in the Features and Components illustrations in Diagrams 1 and 2. The model and rating plate provides heater circuit ratings. There are two main electrical circuits:
Control Circuit: Power supply for the electromagnetic contactor coils. 120V power is supplied to the contactor coils by the CCB (Central Control Board) see wiring diagrams in this manual.
Power Circuit: High voltage, single or three phase, circuit that carries the heating element load.
The following section and pages describe the water heater circuits and includes wiring diagrams.
Control Circuits
The water heater is equipped with an electronic control system. The system includes a CCB (Central Control Board) circuit board, an immersion temperature probe with ECO for temperature sensing and limiting, a UIM (User Interface Module) for user interface & information display and element current sensors for monitoring the power circuits. Refer to the control circuit label on the water heater for details. The CCB is powered by a small 120V/24V transformer. The control circuit operates on 120V supplied by a larger 100VA transformer.
Sequence of Operation
1.When the control is powered, the UIM should display model information, water temperature, operating setpoint, heating status and operating mode.
2.If the control determines that the actual water temperature inside the tank is below the programmed operating setpoint minus the
(1st) differential setpoint, a call for heat is activated.
3.After all safety checks are verified the CCB will energize the contactor coil(s). On models with more than one heating element the upper most heating elements are energized first. Successive heating elements are energized according to programmed differential setpoints for each heating element.
4.The control remains in the heating mode until the water temperature reaches the programmed operating setpoint. At this point the contactors will be
5.The control system now enters the standby operating mode while continuing to monitor the water temperature and the state of other system devices. If the water temperature drops below the programmed Operating Setpoint minus the (1st) differential setpoint, the control will automatically return to step 2 and repeat the heating cycle.
Power Circuit
Power circuit wiring is type THHN (or equivalent) rated 600 volts, 105°C, sized as necessary.
The following wiring diagrams on page 6 are included in this manual to show typical arrangements of electrical components in the control and power circuits by voltage and phase characteristics. They are to be used as a reference by the installer or servicer in performing their work. An actual diagram of the water heater wiring is furnished with the water heater.
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