Accutherm - Model EAT500 Series - Adjustable Electric Water Heater Controller for High Electrical Loads
The EAT500 series controllers by Accutherm are specifically designed to accommodate the high electrical capacity requirements of electric water heaters. These controllers utilize a temperature-sensitive bimetal disc that ensures reliable snap-action contact, facilitating long-term durability even under high electrical loads. The EAT500 series is available in two automatic reset switch actions: SPST (Single Pole Single Throw) and SPDT (Single Pole Double Throw). The SPST model breaks power on temperature rise and automatically resets once the temperature drops. In contrast, the SPDT model accomplishes the same primary function but includes an auxiliary set of contacts for additional circuit actions during transitions. Practical features include a wide supply voltage range (90VAC to 260VAC), relay outputs suitable for 40A at 240VAC, and an operational temperature range from -10°C to 75°C. This makes it ideal for residential electrical storage water heater installations demanding efficient and dependable control solutions.
The EAT500 series of adjustable, automatic reset thermostats is designed to meet the high electrical capacity requirements of electric water heaters. Its design uses a temperature sensitive NTC to provide long dependable control life at electric loads up to 30 amps at 250VAC. The EAT500 can be supplied in combination with our AT500PM manual reset limit as an industry standard electric water heater temperature control/limit.
The EAT500 series controls are designed to meet the high electrical capacity requirements of electric water heaters. Both use a temperature sensitive bimetal disc to deliver snap-action to the contacts. The speed and force of contact separation provides long-dependable control life at high electrical loads.
Switch Actions
The EAT500 is available in two switch actions: Automatic reset SPST – The switch opens the normally closed contacts on temperature rise. The contacts automatically return to the closed position when temperatures return to the reset point. Automatic reset SPDT – This operation is the same as the SPST with the addition of an auxiliary set of contacts, which make circuit upon opening of the normally closed contacts and breaks this circuit upon automatic reset.
- Supply Voltage : 90VAC ~ 260VAC
- Power consumption : 0.6 VA
- Internal sensor: NTC
- Control: ON/OFF control
- Setting : Analog setting
- Control output : Relay output –SPNO, 40A 240VAC
- Storage temperature : -10~80℃
- Operating temperature : -10~75℃
- Temperature accuracy : ± 2℃
- On-off differential : customize
- Insulation resistance : DC500V/100MΩ,AC1200/10mA/1sec.
- Weight : 78 g
- Terminal recommend tightening torque : 15kgf-cm
- Size : 87.6mm x 47mm x 27.2mm
- Life expectancy(Relay): 30000 times (frequency: 900 times/hr)
- Zero-Arc algorithm extends Relay's life cycle
- 10–32 tin plated terminal screws for electrical connections
- Single pole, single throw or single pole, double throw, open on temperature rise construction
- Welded construction used on all internal current carrying components for greater electrical integrity
The thermostats and wiring diagram (shown on next page) are typical of a residential electrical storage water heater installation using two heating elements for non-simultaneous operation. The upper electrical control is a combination EAT500 SPDT regulating thermostat and a AT500PM DPST manual reset limiting thermostat. The lower electrical control is a EAT500 SPST electric thermostat. All the thermostats sense the surface temperature of the water heater tank. The AT500PM function is to provide full power disconnect (through both power conductors) in the event of an overheat condition. The EAT500 SPDT normally closed contacts route power to the upper heating element. When the EAT500 SPDT control reaches its set temperature, its switch action breaks power to the upper heating element and switches power to the lower heating element through the normally closed contacts of the EAT500 SPST. When its set point is satisfied, the switch action breaks power to the lower heating element.