Intermatic WH21 Electric Water Heater Time Switch

Safety Warnings

WARNING Risk of Fire or Electric Shock

• Disconnect power at the circuit breaker(s) or disconnect switch(es) before installing or servicing.
• Installation and/or wiring must be in accordance with national and local electrical code requirements.
• Use #14 - #10 AWG wires, rated at least 90° C - COPPER conductors ONLY.
• Do not remove insulator.
• KEEP DOOR CLOSED AT ALL TIMES when not servicing.
• Turning this switch off will still leave the possibility for hazardous voltage at the water heater.
• More than one circuit breaker or disconnect switch may be required to de-energize the equipment before servicing.

NOTICE

• Rotate timer dial clockwise only.
• Do not move the clock hands on the timer. Moving the clock hands can damage the timer.

Features

• Easy to Install
• External Manual Override Switch: Allows manual ON/OFF control ahead of schedule. The timer resumes the preset program by the next scheduled ON or OFF operation.
• Match Water Heater Off Times to Peak Energy Periods of Utility to Reduce Demand
• External Load Indicator Lamp
• Specifications: 25 A (6250 W) Resistive, 208-250 VAC, 60 HZ; 1500 W Tungsten, 208-250 VAC, 60 HZ; 2 HP, 20 FLA, 80 LRA @ 208-250 VAC, 60 HZ

Installation Steps

Step 1: Checking and Planning

• A. Checking: Ensure Time Switch and water heater voltages match. Verify water heater wattage does not exceed the Time Switch's maximum capacity. Confirm water heater is wired with COPPER wire; do not connect ALUMINUM wires. Consult an electrician if existing wires are ALUMINUM.
• B. Planning and Measuring: Disconnect power before installation. Plan a convenient, eye-level location for the Time Switch, out of reach of children. Measure distances for cable runs, allowing for slack and hook-up leads.
• C. Materials Needed: Depending on wiring (hard-wired or cord/plug connected), obtain appropriate cable, cable connectors, cordsets, and strain relief grommets. Refer to wire gauge selection chart for appropriate wire sizes based on amperage and voltage.
• D. Tools Needed: Hammer, screwdriver, drill, pliers, wire cutter and stripper.

Step 2: Wiring Preparation

• Disconnect power. If cord-connected, remove plug and split cord. If hard-wired, remove fuse or open circuit breaker.
• For cord-connected units: Attach cable and cable connector to the time switch case. Install strain relief grommets and attach cords.

Step 3: Mounting the Timer Case

• Mount the timer case on the wall using provided screws. Use anchors if necessary.

Step 4: Connecting to Water Heater Terminal Box (Hard-Wired)

• Turn off electricity. Note wire colors. Disconnect wires and cable connector from the water heater terminal box.
• Attach prepared cable to the water heater terminal box using a cable connector. Connect wires to water heater terminals, ensuring correct color matching for green/white wires. Tighten terminal screws firmly (20-30 Lb In.).
• Connect the other end of this cable to the time switch case using another cable connector.

Step 5: Connecting Wires to Time Switch Terminals

• Move the insulator out of the way. Connect wires from the service box and water heater to the time switch terminals as per the wiring diagram inside the door.
• Insert only the stripped copper ends of wires under the pressure plates of terminal screws. Tighten terminal screws firmly (20-30 Lb In.). Ensure wire insulation clears the pressure plate.
• Replace the front insulator cover.

Step 6: Securing the Case

• Using pliers, rotate the hasp upward. Install the external push button into the cover by inserting it into the rectangular and round holes and pressing the tabs. Close the cover and adjust if necessary.

Step 7: Setting the Daily Program

• Determine a schedule based on household needs, hot water usage, and appliance use. Consult the electric utility company for time-of-day rates and set the timer accordingly. Consider that hot water quantity and temperature will decline during OFF periods.
• A typical schedule might be ON at 6 a.m., OFF at 8 a.m., ON at 5 p.m., and OFF at 10 p.m.

Step 8: Final Checks and Power Restoration

• Check wiring, time setting (a.m./p.m.), and program. Close the Water Heater Terminal Box if hard-wired. Restore electric service by reversing Step 2.

Operating Instructions

The Time Switch repeats the preset schedule daily, unless the EXTERNAL MANUAL PUSH BUTTON is used to temporarily override the schedule. The timer will resume its program at the next scheduled ON or OFF time.

The diagram shows the mechanism: the TIME MARK aligns with the current time, and ON (silver) and OFF (brass) TRIPPERS are set on the TIME DIAL to control operation times.

To Set Program:

1. Pull and remove the time dial from the timer.
2. Remove all ON (silver) and OFF (brass) trippers.
3. Insert OFF trippers (brass) in desired OFF time slots, ensuring they are not closer than 2 hours apart.
4. Insert ON trippers (silver) in desired ON time slots, ensuring they are not closer than 2 hours apart. ON and OFF trippers can be spaced 1/2 hour apart from each other.
5. Replace the time dial, pushing it in firmly. Rotate the dial to avoid tripper interference with the internal mechanism.
6. Turn the time dial CLOCKWISE until the correct time-of-day is opposite the time mark.

To Stop Automatic Operation (without stopping the timer):

Pull outward on the time dial until it clicks.

To Resume Automatic Operation:

Push inward on the time dial.

After Power Failure:

Reset the time dial to the correct time-of-day.

Diagram of Timer Mechanism:

• INDICATOR LAMP
• ON TRIPPER (SILVER)
• TIME DIAL
• TIME MARK
• OFF TRIPPER (BRASS)
• TERMINAL BLOCK
• MANUAL CONTROL
• GROUNDING SCREW

View of Dial at Midnight: A diagram shows the arrangement of trippers on the dial.

Typical Program: A diagram illustrates a sample ON/OFF schedule.

Extra Trippers: To purchase extra trippers, order part no. 156EB1945A for a set of two (2) ON and two (2) OFF trippers.

Wiring Diagrams

Diagrams are provided for both Hard Wired and Cord and Plug Connected installations, illustrating the connections between the Time Switch, Service Box, and Water Heater.

Wire Gauge Selection Chart:

Contact Information

For additional information or to purchase extra trippers, refer to the Intermatic website or contact Intermatic customer support.