, 66T Series Electric Water Heater Controls 8 Snap-Action Bimetal Discs in Both Controls The and 66T 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. The provides stable temperature control at all pointer settings over a 60 F ( C) adjustable range. The trip-free manual reset 66T operates at a non-adjustable factory calibrated temperature. Features and Benefits The and 66T series features include: Welded construction, used on all internal current-carrying components for greater electrical integrity. The mounting tabs snap into the customer s bracket to mount the thermostat on the surface of the tank. The 66T temperature limit control is available with calibrations from 60 to 0 F (7 to 04 C). The is adjustable over a range of 60 F ( C). Lowest calibration is 90 F ( C) and the highest calibration is 00 F (9 C). Controls are 00% operation checked. Thermal Response of the and 66T The bimetal discs of the and 66T are in intimate thermal contact with the backplates of the controls. Properly mounted, the and 66T series controls provide good thermal response on storage tank water heaters. Switch Actions The 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 contact, which makes circuit upon opening of the normally closed contacts and breaks this circuit upon automatic reset.
RRESET The 66T is also available in two switch actions: Manual reset SPST The switch opens the normally closed contacts on temperature rise. The contacts will reset to the closed position when the reset button is depressed before the control has cooled to 00 F. Once opened and the reset button not pressed, the contacts will not automatically reset at control temperatures above F (0 C). This construction is classified as M Trip Free by approval agencies. Manual reset DPST The operation is the same as the SPST described above with the addition of a separate set of contacts for a second circuit, or full power disconnect (both conductors). SPDT, 66T DPST.59 (40.4).0 (5.9) 40A,0-77VAC 5A, 480VAC T-0-D 66T ESET 5VA, PT.DTY 0-480 VAC 4 4 4,6 (0.7) 50 F 90 F (66 C) ( C) 5 F (5 C) Ø0.9 (5.56) Holes.0 (6.).67 (4.4).00 (50.8).50 (6.5).0 (5.9) 0.50 (.7) SPST.67 (4.4).0 (5.9).67 (67.8) 50 F 90 F (66 C) ( C) 5 F (5 C) Ø0.9 (5.56) Holes.0 (6.).00 (50.8) 0.50 (.7).50 (6.5) 8
Typical Application The thermostats and wiring diagram (see figure ) 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 SPDT regulating thermostat and a 66T DPST manual reset limiting thermostat. The lower electrical control is a SPST thermostat. All the thermostats sense the surface temperature of the water heater tank. L L 66T DPST Limit 4 SPDT Control 4 Upper Heating Element SPST Control Lower Heating Element Figure Double element limited demand circuit for full power disconnect through both power conductors. The 66T function is to provide full power disconnect (through both power conductors) in the event of an overheat condition. The SPDT normally closed contacts route power to the upper heating element. When the 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 SPST. When its set point is satisfied, the switch action breaks power to the lower heating element. 84
RRESET RRESET The thermostats and wiring for single element water heaters are shown below (see figures and ). The combination SPST and 66T DPST is used in residential 40VAC applications, as well as in commercial electric water heater applications where each element may be independently controlled. The combination SPST and 66T SPST finds application in 0VAC single element installations..59 (40.4).0 (5.9) L L 40A, 0-77VAC 5A, 480VAC 66T DPST Limit 66T T-0-D ESET 5VA, PT.DTY 4 0-480 VAC 4 4.6 (0.7) SPST Control 50 F (66 C) 90 F ( C) Ø0.9 (5.56) Holes.0 (6.) 4094 5 F (5 C) Heating Element.67 (4.4).00 (50.8).50 (6.5) 0.50 (.7).0 (5.9) Figure Single element circuit for full power disconnect through both power conductors..59 (40.4).0 (5.9) L 40A, 0-77VAC 5A, 480VAC 66T SPST Limit 66T T-0-D ESET 5VA, PT.DTY 0-480 VAC 4 4.6 (0.7) SPST Control 50 F (66 C) 90 F ( C) Ø0.9 (5.56) Holes.0 (6.) 4094 5 F (5 C) Heating Element.67 (4.4).00 (50.8).50 (6.5) 0.50 (.7).0 (5.9) Figure 0VAC single element circuit for full power disconnect. 85
Calibrations The series temperature regulating controls and the 66T series limit control can be calibrated to meet specific requirements. Typical residential and commercial storage-tank water heater calibrations are shown below. Residential Storage-Tank Water Heaters Series Switch Standard Adjustable Standard Action Temperature Range Calibration 4090 SPST 90-50 F ( -66 C) 0±5 F (49± C) 490 SPDT 90-50 F ( -66 C) 0±5 F (49± C) SPST differential 5-5 F (-8 C) SPDT differential 7-7 F (9-5 C) Series Switch Action Calibration 66T 4490 DPST Manual Reset 70±5 F (77± C) 66T 4590 SPST Manual Reset 70±5 F (77± C) Commercial Storage-Tank Water Heaters Series Switch Standard Adjustable Standard Action Temperature Range Calibration 400 SPST 0-80 F (49-8 C) 40±5 F (60± C) 400 SPDT 0-80 F (49-8 C) 40±5 F (60± C) SPST differential 5-5 F (-8 C) SPDT differential 7-7 F (9-5 C) Series Switch Action Calibration 66T 440 DPST Manual Reset 00±5 F (9± C) 66T 450 SPST Manual Reset 00±5 F (9± C) 86
RRESET The full breadth of calibrations that are available for the and 66T are summarized in the following table. Series Switch Approximate Open Temperature Standard Action Adjust. Range ±5 F ( C) Differential SPST 60 F ( C) Max 00 F (9 C) 5-5 F (-8 C) Min 90 F ( C) SPDT 60 F ( C) Max 00 F (9 C) 7-7 F (9-5 C) Min 90 F ( C) Series Switch Open Standard Standard Action Temperature Tolerance Reset 66T SPST Max 0 F (04 C) ±5 F (± C) M Trip Free Min 60 F (7 C) 66T DPST Max 0 F (04 C) ±5 F (± C) M Trip Free Min 60 F (7 C) A broad selection of dial plates for non-standard calibrations are available using F, C or Low-Medium-High markings. 66TM Options Both the 66T SPST and 66T DPST are available with the 66TM mounting option shown below. The flanges on the backplate allow the 66TM to be screw or stud-mounted. 0. (5.) 40A,0-77VAC 5A 480 VAC T-0-D ESET RESET RESET.6 (4.4).8 (46.0).88 (55.58).6 (66.6) 5 VA, PT. DTY 0-480 VAC 4.6 (4).00 (5.4) L5F 0659 DATE 66TM 4655 87
Clamp Bracket Clamp bracket for series thermostat are made for use with tanks having a bolt-on type heating element. Temperature Limiting Stops Stops are available to restrict the normal 60 F ( C) range of adjustment from the minimum setting position. Stop P/N Restricted Range 5609 50 F (8 C) 560 40 F ( C) 56 0 F (7 C) 70 F 60 50 0 0 40 0 88
General Electrical Ratings The, 66T series of controls has been rated by major agencies throughout the world. The agency ratings can be used as a guide when evaluating specific applications. However, the mechanical, electrical, thermal and environmental conditions to which a control may be exposed in an application may differ significantly from agency test conditions. Therefore, the user must not rely solely on agency ratings, but must perform adequate testing of the product to confirm that the control selected will operate as intended in the user s application. Thermostat Max Comments Inductive Pilot duty Resistive Volts Agency Type Temp. Cycles Amperes VA Amperes Watts AC Recognition FLA LRA 00,000 0.0 50 UL 4000-4099 70 F 5.0 77 File E979 (SPST) 400-499 70 F 0,000.5 480 (SPDT) 400-499 7-00 F 0,000 5 0-480 (SPST) 400-499 7-00 F 0,000 7. 4. 0 (SPDT) Motor Load in Parallel With 600VA Ignition Transformer 66T, 66TM 0 F 6,000 40.0 77 4400-4499 6,000 5.0 480 4500-4599 6,000 5 0-480 SPST & SPST only 0,000 0.0 50 CSA SPDT SPST & SPDT 0,000 5.0 77 File LR08 4000-4099 70 F SPST & SPDT 0,000.5 480 400-499 70 F SPST & SPDT 0,000 5 0-40 400-499 0 F 400-499 00 F 66T, 66TS 0 F 6,000 40.0 77 4400-4499 6,000 5.0 480 4500-4599 6,000 5 0-480 0 C SPST, SPDT 00,000 0.0 50 - and -4 00,000 6.0 80 VDE* 66T, 66TM 75 C Calibration 0 50.0 50 094 75 F Switchcase 0 0.0 80 /66T 0.0 40 Victoria CS8V NOTE: For complete and current rating information, please contact our Sales Engineering Department. At thermostat end-of-life, the contacts may remain permanently closed or open. * For other European agency ratings, please contact our Sales Engineering Department. Important Notice Users must determine the suitability of the control for their application, including the level of reliability required, and are solely responsible for the function of the end-use product. These controls contain exposed electrical components and are not intended to withstand exposure to water or other environmental contaminants which can compromise insulating components. Such exposure may result in insulation breakdown and accompanying localized electrical heating. A control may remain permanently closed or open as a result of exposure to excessive mechanical, electrical, thermal or environmental conditions or at normal end-of-life. If failure of the control to operate could result in personal injury or property damage, the user should incorporate supplemental system control features to achieve the desired level of reliability and safety. For example, backup controls have been incorporated in a number of applications for this reason. 89