Fix the electric water heater reset switch:
This article describes how and why to test the high temperature cutoff switch and how to use the hidden reset switch on electric water heaters.
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Before testing the electric water heater elements we should check out the high temperature cutoff switch since a problem there will simply turn off power to both heating elements.
On an electric water heater the upper heating element may have two, three, or four electrical terminals, and above the upper thermostat is a high temperature cutoff switch with four terminals. You should be able to identify these parts by looking at the water heater's wiring diagram found on the tank or inside the panel cover.
The electric water heater high-temperature cutoff switch will turn off the entire water heater if temperatures are too high. If this cutoff is not working the water heater will simply not heat at all. You can use this switch to test to confirm that the incoming electrical power circuit is indeed bringing power to the water heater.
General electrical inspection safety advice is
at SAFETY for ELECTRICAL INSPECTORS.
Set the multi tester or VOM to its 250 VAC scale, and attach the tester probes or alligator clips to the two uppermost terminals on the control (L1 and L3 on the top left and top right in our photo below). These are normally the incoming electrical wires from the power circuit to the heater. "L" refers to "Line voltage" on most controls.
Test for line voltage: Now you can turn on electrical power to the heater. Your VOM should show voltage close to the voltage on the water heater's identification tag: typically this will be 208V or 240V for a 240V water heater, or it might be just 115V or 120V for a 120V water heater. If you do not see voltage close to the rated voltage you need to call an electrician to diagnose and repair the problem.
Test the High Temperature Cutoff Switch itself: set the VOM to its Ohm or resistance scale using the most sensitive setting (R x 1).
If you cannot reset the control then this device is not working and it needs to be replaced.
FYI we do not usually find a problem with this electric water heater high limit cutoff switch.
The most common problem on an electric water heater that is not heating is a burned-up water heating element - tests that we describe
at ELECTRIC WATER HEATER ELEMENT TESTS
We suddenly find we have no hot water. I have an electric hot water heater. - Paul 11/1/12
Check that the water heater has electrical power, then try pressing the reset switch described above.
Electric water heaters are among the easiest to troubleshoot;
There are just a few things to check, easily done with a digital multimeter (DMM)or volt ohmeter (VOM). Just go through the list starting with the links below at
Electric Water Heater Repair Guide (link shown below)
- that water flows into and out of the heater
- for power to the heater
- that the thermostatic control is functional (article above)
- that the heating elements are not burned out
See ELECTRIC WATER HEATER REPAIR GUIDE for our complete & detailed electric water heater troubleshooting procedures.
Watch out: removing access covers on an electric water heater exposes live voltage-wires: touching them can cause injury, shock, or death.
Continue reading at ELECTRIC WATER HEATER INSPECTION CHECKLIST or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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Recently-posted water heater temperature control questions & answers
On 2017-02-18 23:24:09.260391 by (mod) - water heater upper element failed after it was replacedStart by testing to see if the element has failed - a likely event if all air was not purged from the water heater tank
On 2017-02-16 14:56:28.977317 by TerrenceI have replaced the upper element on my hot water heater. It worked for about 5 hours then the diagnosis reader indicated that the upper element was bad again. The water was hot until this happened then I got no hot water again. I hit the reset button it heated up but later I got the same problem. Why is this happening?
On 2017-01-24 14:07:26.448734 by MORGANThe red botom is popped i thinkas i can not push it and hard, but the heather still working?
On 2017-01-16 00:14:00.467178 by (mod)
If the water heater is not getting power, then none of the components that have been replaced are likely to be at fault. Start at the electrical panel.
Is the power to the water heater turned on. You may need an electrician to avoid risk of being killed by electric shock, but a professional would use a meter at the electrical panel to confirm that the circuit breaker when switched on is actually delivering power to the circuit.
Once me know that the wires are alive leaving the breaker we check at the other end of the circuit at the water heater. If there's no power there than you have an open wire in the circuit. If there's power where the circuit enters the water heater, then you've made a wiring error. Watch out there is danger of electrocution fooling with these wires, as well as fire.
On 2017-01-15 22:42:45.143726 by JerryI replaced both heating elements, both thermostats (top and bottom) and installed a new 20amp 220 breaker in the house panel box......the water heater is not getting power......does not heat...also, the red reset button does not pop out, which was the original problem, that thermostat button never popped out as the cause of failure........what to do to start heating
On 2017-01-13 23:56:19.813423 by (mod)George,
On 2017-01-13 23:39:41.953093 by GeorgeEvery other week my ECO trips on my electric water heater; easy to reset. I tested the upper and lower elements at 12.8 ohms on 4500 watt elements. ResistNce from all leads to the water tank was infinite, no short. Turned power on to cold tank; upper element powered up, then thermostat shut down; lower element powered up then shut down by thermostat. How can I analyze further this intermittent problem?
On 2016-12-27 00:56:43.682076 by (mod)Sounds unsafe, Alice. I think perhaps your water heater thermostat has failed. It's time to call for repair.
On 2016-12-27 00:22:42.983863 by AliceI have a hot water heater only about 7 years old. Recently I have noticed that the Hot Water is Scalding hot. I had the temperature lowered when it was installed but now the temperature seems to have Changed by itself. Single handle faucet and if I so much as get near center the water is scalding hot. Can you give me a clue as to what it wrong and what I need to do? I now how to change the T-stats myself but I am not sure that is the problem.
On 2016-10-19 12:29:42.257475 by KennyCan anyone tell me what needs replacing to clear this code?
On 2016-10-19 11:46:45.357485 by KennyI am getting an e02(water temp exceeded high limit), it resets and comes back, all the elements are good, voltages are good. The water is not excessively hot.
On 2016-08-01 21:50:58.602772 by (mod)Yes
On 2016-06-08 00:14:13.847963 by AnonymousI have power to both elements at the same time is this normal?
On 2016-03-21 13:01:55.569992 by (mod)Ken
On 2016-03-21 11:14:55.928542 by kenOccasionally the water temperature from my electronic water heater becomes scalding hot. Then is usually trips the reset switch. I have replaced both elements but the problem persists. Any ideas.
On 2016-03-14 13:40:57.014830 by (mod)Changing the relief valve should itself have not one iota of impact on water pressure. However if the plumber had to turn off water valves and perhaps drain some water from the water heater during the repair, the problem may be at the valve that was adjusted; it may not be fully open, or it may be damaged such that it will not open fully even when the handle is turned.
On 2016-03-14 13:29:05.893781 by Stephanie,grishamJust had the pressure relief valve on my electric hot water heater replaced. Now, the water pressure is very low when hot water is,turned on. What would cause this & how can I fix it?
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