• Electric Water Heater Controls
  • Electric Water Heater Controls
  • Electric Water Heater Controls
  • Electric Water Heater Controls
  • Electric Water Heater Controls
  • Electric Water Heater Controls

Electric Water Heater Controls

The 59T series of adjustable, automatic reset thermostats is designed to meet the high electrical capacity requirements of electric water heaters. Its design uses a snap–action, temperature sensitive bimetal disc to provide long dependable control life at electric loads up to 30 amps at 250VAC. The 59T can be supplied in combination with our 66T manual reset limit as an industry standard electric water heater temperature control/limit.
Model : 59T, 66T Series

Snap-Action Bimetal Discs in Both Controls

The 59T and 66T series Bimetal Thermostat Temperature 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.

Thermal Response of the 59T and 66T

The bimetal discs of the 59T and 66T are in intimate thermal contact with the backplates of the

controls. Properly mounted, the 59T and 66T series controls provide good thermal response on

storage tank water heaters.

 

Switch Actions

The 59T 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.

The 66T is a manual reset DPST – The switch opens two sets of normally closed contacts on temperature rise to provide full power disconnect of both conductors. The contacts will reset to the closed

position when the reset button is depressed before the control has cooled to 90°F. Once opened,

until the reset button is pressed, the contacts will not automatically reset at control temperatures

above 32°F (0°C).

The construction is classified as “M2 Trip Free” by the approval agencies. This patent pending

design holds the contacts open in the event the reset button is held in the depressed position in

an attempt to defeat the manual reset function of the thermostat.

• Welded construction, used on all internal current-carrying components for greater electrical
integrity.
• The 59T mounting tabs snap into the customer’s bracket to mount the thermostat on the
surface of the tank.
• The trip free manual reset 66T limit control is available with non-adjustable calibrations from
160° to 235°F (71° to 113°C).
• The 59T has an adjustable range of approximately 60°F (33°K). The lowest adjustable limit is
90°F (32°C) and the highest adjustable limit is 200°F (93°C).
• Controls are 100% operation checked.

The thermostats and wiring diagram (shown on page 31) 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 59T SPDT regulating thermostat and a 66T DPST manual

reset limiting thermostat. The lower electrical control is a 59T SPST thermostat. All the thermostats sense the surface temperature of the water heater tank.

The 66T function is to provide full power disconnect (through both power conductors) in the

event of an overheat condition. The 59T SPDT normally closed contacts route power to the upper

heating element. When the 59T 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 59T SPST. When its set point is satisfied, the switch action

breaks power to the lower heating element.

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