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Here we describe 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. If you cannot find information you need here or if you have comments, questions, suggestions for inspecting and diagnosing water heaters Contact Us

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

How to Test Electric Water Heater Heating Elements

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 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 at Water Heater Noises.

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. For details on how to use electrical test equipment see Using DMMs & VOMs Safely and see Voltage Measurement & Detection. General electrical inspection safety advice is at SAFETY FOR ELECTRICAL INSPECTORS.

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

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 Ohmeter 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 Ohmeter 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

We do not usually make this test but we include it here as it appears in some diagnostic procedures for electric water heaters.

1. Turn off electical 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.

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 Noises for details about removing scale from a water heater.

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WATER HEATERS
AGE of WATER HEATERS
ALTERNATIVE HOT WATER SOURCES
  Electric Shower Heaters
  High Efficiency Water Heaters
  Indirect-fired Water Heaters
  Instantaneous Water Heaters
  Multiple water heaters in parallel
  Multiple water heaters in series
  Range Boiler Water Heaters
  Side Arm Coil Water Heaters
  Solar Water Heaters
  Tankless Coil for Hot Water
  Tankless Water Heaters
ANODES & DIP TUBES on WATER HEATERS
ANTI SCALD VALVES
ELECTRIC WATER HEATERS
  Identify Electric Water Heater Parts
  Electric Water Heater Checklist
  Electric Water Heater Controls List
  Water Heater Anode & Dip Tube Check
  Hot Water Temperature & Pressure Valve
  Electric Water Heater Repair Guide
  Electric Water Heater: No Hot Water
  Electric Water Heater Reset & Temp Set
  Test Electric Water Heater High Temp Cutoff
  Test Electric Water Heater Elements
  Replace Electric Water Heater Element
  Drain a Hot Water Heater Tank
HOT WATER IMPROVEMENTS
HOT WATER QUANTITY IMPROVEMENT
INDIRECT FIRED WATER HEATERS
ODORS IN WATER
OIL FIRED WATER HEATERS
MIXING VALVES
RANGE BOILERS
RELIEF VALVES - TP Valves on Boilers
Relief Valves - Water Heaters
SOLAR HOT WATER HEATERS
TANKLESS COILS
Water Heater Noises
WATER HEATER PROPERTIES
  Electric, Gas, Oil Water Heater Efficiency
  Water Heater Life Expectancy Comparisons
  Water Heater Operating Cost Comparisons
  Water Heater Purchase & Maintenance Costs
  Water Heater Water Quantity Comparisons
  Water Heater Recovery Speed Comparisons
  Water Heater Safety Comparisons
Water Heater Scale - De-Liming Procedures
WATER SOFTENERS

• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

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