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Electric Water Heater Heating Element Terminals (C) Daniel FriedmanHow to Test for a Bad Electric Water Heater Heating Element
Diagnose electric heater elements for geysers, water cylinders, electric water heaters

  • ELECTRIC WATER HEATER ELEMENT TESTS - CONTENTS: Electric Water heater elements: how to inspect, test, adjust, repair a water heater element. Ohm chart of measured resistance of electric water heater heating elements for common rated wattages. How to find & replace an electric water heater heating element that is not working. How to test and repair an electric hot water heater that is producing only tepid hot water or not enough hot water,. Test procedures for electric water heater heating elements. How to replace the heating element on an electric water heater
  • POST a QUESTION or READ FAQs about how to test the heating elements on an electric water heater
  • REFERENCES
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Electric water heater element test procedure: this article describes how to test electric hot water heater heating elements, what readings to expect if using an ohmmeter. This article describes the steps in testing electric hot water heater heating elements, followed by a guide to replacing a bad heating element.

This series of articles describes how to inspect, operate, diagnose, and repair electric hot water heaters. The articles at this website will answer most questions about electrical water heaters as well as many other building plumbing system inspection or defect topics. Reproduction of this web page electronically at other websites is prohibited.



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How to Test Electric Water Heater Heating Elements

Operating Sequence of Electric Water Heater Elements upper and lower heating elements

Water heater element sequencing in electric water heater (C) Carson Dunlop AssociatesNote: Once you have diagnosed which heating element is bad, also see Electric Water Heater Element Replacement.

Because the electric water heater might be failing to work due to loss of electrical power to the unit, or because of a malfunctioning high-temperature cutoff switch, you should also see the test steps
at How To Test High Temperature Cutoff Switch

Electric water heater drawing (left) showing the sequencing procedure for electric water heater elements is provided courtesy Carson Dunlop Associates, used with permission

Electric water heaters have two heating elements - thick metal loops that get hot when electricity flows through them, similar to the burner on an electric range.

The lower heating element heats cold water as it enters the hot water tank. (Incoming cold water is delivered to the bottom of the tank through the dip tube.)

This element works the hardest, is on the most, and so often is the first to burn out. The upper heating element acts as a "booster" to heat water when there is a high demand. This element heats only the water in the upper portion of the hot water tank.

As we introduced earlier, if there is some hot water but it is limited in quantity or temperature, just one of the heating elements may have failed.

Scale coating a water heater element can also reduce the quantity of hot water (or cause heating element failure) - a topic we review in more detail
at WATER HEATER SCALE DE-LIMING PROCEDURE
and
at WATER HEATER NOISE DIAGNOSIS, CURE

If the electric water heater produces the same old quantity of hot water, but water is only tepid rather than hot, we suspect that the top water heater element has burned out. The bottom element is heating the entire tank but it is not capable of heating the water to the same high temperature as if both elements were working. Long tepid shower - bad top water heater element.

If the electric water heater produces the same old hot water temperature, but the quantity seems drastically reduced, we suspect that the bottom water heater element has burned out. Only the water in the top of the tank is being heated. Cold water enters and remains at the bottom of the water heater. So our hot water is plenty hot but we run out in just a few minutes. Short hot shower - bad bottom water heater element.

As we're about to show in detail, one can test a water heater heating element by a simple procedure using a continuity tester or a volt-ohm meter- a VOM.
See DMM DIGITAL MULTIMETER HOW TO USE

For details on how to use electrical test equipment see DMMs VOMs SAFE USE OF

and see VOLTS / AMPS MEASUREMENT EQUIP

Steps in Testing an Electric Water Heater Heating Element - Good Method

Electric Water Heater Heating Element Terminals (C) Daniel FriedmanReader Question: our water won't get hot - electric water heater

Water will not get hot when turn on hot water in house - Claude 11/29/12

Reply:

Claude, you may need to replace your water heater elements. See the test steps given in the article below:

  1. Turn off electrical power to the water heater - you should have done this earlier if you read the instructions above. Turn off power at the water heater circuit at the main electrical panel.
  2. The water in the heater should be lukewarm or colder. If the water heater is hot, run hot water in the building (with the water heater electrical power OFF) until water flows lukewarm or colder.
  3. Disconnect the electrical wires at the heating element terminals. (This is so whether testing upper or lower heating element).
  4. Test for current flow: Use a VOM, DMM, or Ohmmeter or multimeter set to read "resistance" or "ohms" as follows: connect one alligator clip or touch one probe of the VOM to each terminal on the water heater element.

    One probe touches one terminal, the other probe touches the other terminal. If the Ohmmeter needle doesn't move (or no reading is given on the DMM) then the electric water heater heating element is defective and needs to be replaced.

    If the ohmmeter needle moves or you get some Ohm reading (other than infinity) then the heating element is OK and you are ready to test the other heating element on the heater. In sum, if there is "continuity" through the heating element it is working. If there is no continuity (no electrical current can flow) then the element has failed.

Testing an Electric Water Heating Element for a Short Circuit - Crude Method & OHM Table for Water Heater Elements

Water heater electric element ohms chart - AO SmithWe do not usually make this test but we include it here as it appears in some diagnostic procedures for electric water heaters. The water heater element OHMS chart (left, courtesy A.O. Smith) describes the actual ohm reading you'd expect if testing a factory OEM heater element of the wattage shown.

Even without that level of detail there is a simple test you can perform to see if an electric water heater heating element is in good working order:

  1. Turn off electrical power to the water heater - you should have done this earlier if you read the instructions above. Turn off power at the water heater circuit at the main electrical panel.
  2. Remove the access panel cover and insulation from the top or bottom water heater element (described above)
  3. Connect the alligator clip or test terminal of your continuity tester to one terminal of the heating element. That's the wire and screw right on the heating element itself.
  4. Connect the other probe of the continuity tester (or VOM) to a bolt or bracket that holds the heating element in position.
  5. If the test light goes on, the buzzer sounds, or your VOM (set to Ohms) indicates continuity, there is a short circuit in the heating element and it needs to be replaced.

More water heater element test recommendations are in the Residential Gas and Electric Water Heater Handbook [PDF] provided by A.O. Smith and linked-to at REFERENCES

Causes of Heating Element Failure on Electric Water Heaters

Besides old age and high usage, if your building water supply provides hard water (high in mineral content), scale build-up on water heater elements can lead to their demise.

See WATER HEATER NOISE DIAGNOSIS, CURE for details about removing scale from a water heater.

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Continue reading at ELECTRIC WATER HEATER ELEMENT REPLACEMENT or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see DMM DIGITAL MULTIMETER HOW TO USE

Or see ELECTRIC WATER HEATER REPAIR GUIDE - home

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