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How to replace thermostat on electric water heater

How to replace thermostat on gas water heater
Upper and lower thermostats
   Make lower thermostat from upper

Buy generic upper and lower thermostats

Buy 90-150 degree F for residential tank:
Water heater thermostats at Amazon
Camco thermostats at Amazon
More thermostats
Shorter style 89T single-element thermostat at Amazon
89T13 dual-element thermostat at Amazon
89T13 dual element kit with jumper wire
Example Camco dual-element thermostat at Amazon
Buy/ 3 phase water heater thermostat 120-180 degree F
Camco 120F to 180F thermostat (commercial grade only)
Camco 180F lower thermostat (commercial grade only)
Read more about 3-phase water heater

Residential tank thermostat is rated 90-150 F
Only use 180 F thermostat on commercial water heater that is rated for that temperature

Best to replace both thermostats.

There is no guaranteed way to test themostats. If thermostat is sticking, then test includes rotating temperature knob which can temporarily unstick thermostat. So bad thermostat appears to work correctly.
Upper Thermostats
Larger image

Thermostat for dual-element tank has 3 screws on right side.
Thermostat for single-element tank has 2 screws on right side.
Dual element thermostat will work in place of single-element, but single-element thermostat will not work for dual.

All dual element tanks are 208-240V.
All dual-element and single-element thermostats works on either 120 or 208-240Volt water heaters

Upper thermostats have ECO reset button that trips when temperature reaches 150-170
Shorter style 89T single-element thermostat at Amazon
89T13 dual-element thermostat at Amazon
89T13 dual element kit with jumper wire
Therm-o-disc thermostat protectors

Thermostat protectors/

terminal protectors for therm-o-disc
Therm-o-disc upper element terminal protector
Therm-o-disc lower element terminal protector

Replacement steps start here

220 Volt circuit breaker
Power if OFF
Do not empty water out of heater

Turn power OFF

Turn off 20 or 30 Amp circuit breaker to 240V water heater See basic water heater wiring diagram
Or 20 Amp circuit breaker to 120V water heater

Check label on side of water heater for appliance voltage Figure volts amps watts
Wattage is stamped on end of element see example

water heater element

Never assume power is OFF/ Use non-contact voltage tester

Use non-contact voltage tester on timer, on wire, on outlet to see if power is present.
Press button on tester, if single beep then no power is present. If continuous beep then power is present.
Never stand on bare ground, always stand on dry boards, do not hold or touch anything metal when working on timer or water heater that has power, tape tester leads to wood sticks, never touch wet water heater, or flooded water heater, or timer that had a short or fire without turning power OFF.

Multimeters at Amazon
Buy non-contact voltage tester at Amazon
Electric testers at Amazon

Shop Amazon - Industrial and scientific
Shop Amazon - Industrial Electric Products

Test water heater
How to find age of water heater

How to use ordinary tester/ 120, 208, or 240V:

Stand on dry boards
Never touch wet water heater unless power is OFF
Tape tester leads to wood sticks

1. Test black wire to ground wire

2. Test black wire to white wire

3. Test white wire to ground wire

If indicator lights up, then electricity is present.
water heater thermostats
Newer tanks have foam insulation that may need to be cut back. Insulation must be re-installed.

Do not empty water out of heater

Not necessary to wait for water to cool. Can be done with hot water inside tank.
Power must be OFF.
Use screwdriver to remove covers and insulation from tank

Some 240Volt tanks have single access door and single thermostat
Buy new parts that match old
Buy parts at hardware store
Thermostats and elements are generally interchangable between brands of electric water heater
Exception is Whirlpool energy-smart shown lower on page.

Thermostat cover
Thermostats usually covered with plastic protector shield.
New protector shield packaged with some new thermostats
Purpose of protector is to protect homeowner from electrocution when pushing reset button or adjusting temperature when power is ON.
Older heaters may not have plastic shield.
Replace water heater thermostat
Larger image
See large image of overall wiring diagram
Wire colors can vary
Take photo of wiring before starting.

See upper thermostats showing numbers

Steps to replace thermostat

Instructions are same for both upper and lower thermostats
Power is OFF, and tested that power is off using steps above

Use digital camera and take photo of wires or draw picture showing location of each wire
Remove wires from thermostat
Thermostat is held in place by metal spring that snaps over ears on thermostat
Pull back metal spring on both sides (make a tool using piece of coat hanger wire)
Slide out old thermostat
Put new thermostat in place, wiggle thermostat around to make sure it is held flat and tight against tank by metal spring
Thermostat reads temperature through surface of metal tank
Use screwdriver to adjust temperature
See images showing how to adjust temperature to 120 (or higher if hot water runs short)
Re-connect wires <> tighten screws very firm against copper wire
Important .... Push-in red reset button firmly to make sure it is engaged
After thermostat is replaced, put factory insulation back over thermostat
Insulation must cover thermostat to avoid higher water temperatures than desired set point
Tank must be full of water or elements will instantly burn out
Turn power ON
Put ear against water heater to hear bubbly fizzing sound that says water heater is 'on'
If tank is fully heated, water heater will not turn on. If tank is partially heated, then lower element will turn on. If tank is cold, then upper element will turn on. How it works
Put access doors back on tank
Access doors and insulation are required for thermostat to read correct temperature

If water heater is still not working, see troubleshooting

Fire safety

Fire safety

All wires must be same gauge (same diameter). Or connect different gauge wires using push-on wire connectors
Only copper wire used.
Solid wire only. Never use stranded wire.
Only copper under screw plate, no insulation under screw plate.
Maximum 2 wires under screw plate.
Wires must be fully inserted under screw plate. And screw plate very tight against wires.
Wires cannot run over top of thermostat or elements, and must be pushed aside.
Wires can run over top of other wires, but not at point where wires are making connection to either element or thermostat.

Use push-on wire connectors when wires are too short

Push on wire connectors at Amazon
Red 3P connector (shown) for 10-14 gauge wire

Push on wire connectors
Back of thermostat

Thermostat must sit flat against tank

Wiggle thermostat to make sure it sits flat against tank
Thermostat sits flat against tank wall so temperature reading is accurate and water heater is protected from overheating

Access doors and insulation must be put back over thermostat to avoid higher water temperatures than desired set point, which leads to overheating, which will trip ECO reset.

See larger

Double-check thermostat wiring

Compare wiring with illustration

How to wire thermostats
How water heater thermostats work

Red reset button:
ECO energy cut off turns off power to water heater when temperature reaches 150-170
Test upper thermostat

Adjust temperature on thermostat using screwdriver.

Recommended temperature is 120 degrees F for efficiency and to avoid scalding water.
If home is running short of hot water, turn temperature up.
Thermostat setttings are approximate. Calibration is different for each thermostat. Use cooking thermometer to measure water temperature when exact temperature is needed.

Problems from high temperature setting include higher bill, faster sediment build-up.
Minerals can distill out of water when water is above 140 degrees.
Water expands with higher heat. TP valve releases water. Pressure should not exceed 80 psi.
How to adjust water heater temperature
9 ways to save with water heater
Test and replace TP valve.
Install expansion tank.
Inspect for leaks once per year.
Test for high water pressure over 80psi that can damage tank and pipes
Formulas and terminology

Additional information

Burned thermostat
Burned thermostat

What caused it?
Electricity found path from terminals on thermostat to bare metal tank. But fire did not spread because tank factory-installed covers and insulation were on side of tank
Always connect ground wire to water heater
Always keep insulation and cover installed on tank.

Inspection finds Burned thermostat or melted wire

Turn power OFF
Replace part
Test wires

Test wires with Multimeter
Multimeters at Amazon

How to test continuity of wire: When burned wire is discovered/ or suspect

Set multimeter to read ohms.
Disconnect wires from each tank part.
Test #1: Put tester leads on both ends of wire.
If test reads ohms, then wire is good.

Test #2: Test each end of wire to bare metal part of tank.
If test reads ohms, then wire is shorted and must be replaced.
Bad wire: Tanks with foam insulation may need to be replaced

Water heater construction

Steel tank is covered by insulation and metal shell.
Insulation and shell protect wiring.
9 ways to save with water heater

Anode rod is necessary to stop steel tank from rusting

Insulation and cover must be over thermostat.

Exposing thermostat to cool room temperature will cause tank to overheat.
Thermostat cannot read correct temperature unless covered correctly.

Troubleshoot electric water heater
Energy-smart electric water heater does not have thermostat
Temperature sensor sends information to self-diagnostic control on top of heater
Newer energy-smart electric has electronic thermostat.
Thermostats are ordered from Whirlpool 1-877-817-6750, elements are generic and can be bought locally.
Whirlpool self diagnostic control
If you have: Self diagnostic control

Temperature-sensor ordered from Whirlpool or Craftmaster etc

Serial number + $37 required > instructions included with order

See more about Whirlpool Energy Smart
Flooded water heater must be replaced:

Insulation is wet.
Wet water heater is immediate electrocution danger. Turn power OFF.
Insulation cannot dry unless covers are left off tank.
Covers are required for thermostat to read correct temperature.
Water heater must be taken out of service until completely dry.

Flooded water heater
Leaking water heater
Basic parts on top of electric heater
Parts vary slightly depending on model and brand

Anode rods
Test and replace TP valve
Water heater valves
Replace drain valve
Water heater will not drain
Dip tubes
Low water pressure
Non simultaneous operation 240 volt residential water heater is wired for non-simultaneous operation:
Both elements are not ON at same time.
Upper is ON, or lower is ON, or both are OFF.
Action is controlled by upper thermostat.

How thermostats work
How electric water heater works
Water heater must be full of water or elements instantly burn out.
How to fill water heater:
Turn tub spout ON until full stream.
Open water heater TP valve for a moment to release last of air.
Turn power ON.

How electric water heater works
How to test and replace TP valve

Additional links
Gas valves Gas water heater thermostat is connected to gas control valve.
When thermostat goes bad, the gas control is replaced using identifying numbers on side of control.
How to troubleshoot gas water heater, and replace thermostat on gas water heater

How to replace gas control thermostat
Replace gas control

Electricity from pole to breaker box

See basic 120V and 240V water heater circuits

Compare all water heater timers
Do it yourself
Do it yourself water heater

How to twist wire

How to wire off-peak water heater

How to install and troubleshoot gas water heater
Leaking water heater
Troubleshoot leaking water heater
Cutler Hammer C25BUB230A
Recirculation system
Hot water circulation system
Troubleshoot Rheem tankless

Troubleshoot Bosch tankless
Solar water heater
9+ ways to save with water heater

Motorized shut off valve

Anode rods

Clean sediment from tank
Gas and electric water heaters Support the economy:
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50 gallon Gas water heaters at Amazon
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How to install gas water heater
Troubleshoot gas water heater
Troubleshoot electric water heater
Gas and electric water heaters Industrial electric at Amazon

Industrial supplies at Amazon

Industrial and scientific Amazon
Intermatic control centers Control centers:
+ manuals and parts

All control centers and parts

Including Z-wave
box timers Compare box timers

Control with Z-wave
programmable timer Compare programmable timers

Control water heater with programmable wall timer
Countdown timers Compare countdown timers

Control water heater with countdown timer
Compare power packs
Yard and Christmas timers Yard and Christmas timers
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