Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
Ask a Question or Search InspectAPedia
InspectAPedia ® Home
AGE of WATER HEATERS
AIRBOUND HEAT SYSTEM REPAIRS
ALTERNATIVE HOT WATER SOURCES
ANODES & DIP TUBES on WATER HEATERS
ANTIFREEZE for BOILERS
ANTI SCALD VALVES
APPLIANCE EFFICIENCY RATINGS
AQUASTAT CONTROL Functions
BACKDRAFTING HEATING EQUIPMENT
BACKFLOW PREVENTER, HEATER WATER FEEDER
CARBON MONOXIDE - CO
CHECK VALVES, WATER SUPPLY
CHEMICAL CONTAMINANTS in WATER
CHIMNEY INSPECTION DIAGNOSIS REPAIR
CLOGGED SUPPLY PIPING
DEBRIS in WATER SUPPLY, Water Heater
DRAIN a WATER HEATER TANK
ELECTRIC WATER HEATERS
FLOODED HEATING EQUIPMENT REPAIR
FLOODED WATER HEATER REPAIR
GALVANIC SCALE & METAL CORROSION
GAS BURNER Flame & Noise Defects
GAS FIRED WATER HEATERS
GAS PIPING, VALVES, CONTROLS
HOT WATER SUPPLY
INDIRECT FIRED WATER HEATERS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
NO HEAT - NO HOT WATER: HEATER DIAGNOSIS
NOISE / SOUND DIAGNOSIS & CURE
NOISE CONTROL for HEATING SYSTEMS
NOISE, PLUMBING CHECKLIST
NOISE, WATER HEATER
ODORS GASES SMELLS, DIAGNOSIS & CURE
ODORS IN WATER
PIPING IN buildings, Clogs Leaks Types
PLASTIC HEATER VENT
PLUMBING FIXTURES, KITCHEN, BATH
RELIEF VALVE LEAKS
RELIEF VALVES - Water Heaters
SCALE REMOVAL, WATER HEATERS
SEWER GAS ODORS
SOLAR HOT WATER HEATERS
SOOT on OIL FIRED HEATING EQUIPMENT
SPILL SWITCHES - Flue Gas Detection
TANKLESS WATER HEATERS
Temperature Pressure Relief Valves - Water Heaters
THERMOSTATS, WATER HEATER
TIMERS for ELECTRIC WATER HEATERS
WATER CONTAMINANT LEVELS
WATER HAMMER NOISE DIAGNOSE & CURE
WATER ODORS, CAUSE CURE
WATER PIPES, Clogs Leaks Types
WATER PRESSURE & FLOW MEASUREMENT
WATER PRESSURE LOSS DIAGNOSIS & REPAIR
WATER QUANTITY IMPROVEMENT
WATER SOFTENERS & CONDITIONERS
WINTERIZE A BUILDING
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 (Electric Water Heater Element Replacement). 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
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Operating Sequence of Electric Water Heater Elements upper and lower heating elements
Note: 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 WATER HEATER SCALE PREVENTION and 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 DETECTION & MEASUREMENT. General electrical inspection safety advice is at SAFETY for ELECTRICAL INSPECTORS.
Steps in Testing an Electric Water Heater Heating Element - Good Method
Testing an Electric Water Heating Element for a Short Circuit - Crude Method & OHM Table for Water Heater Elements
We 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:
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.
See Electric Water Heater Element Replacement for the steps in replacing a bad electric water heater heating element.
Frequently Asked Questions (FAQs) about how to test for a bad electric water heater element
Question: lightning strike damaged the water heater wiring/element
I just replaced the lower element today. The test by continuity to both screws was ok but from one (1) screw to ground was not. Bad element; short circuit. Lightning had struck a large pine tree in the front about 40 yards from heater two days ago. All breakers did their job well by shutting down the power to heater and the breaker in heater shut down also. - Lloyd 3/23/12
Tanks Lloyd, that's helpful details.
Question: Keith thinks you cannot use a VOM or DMM to test water heater elements by checking resistance
You cannot ohm the elements, since if open the water will show continuity.
I don't think you've got it correct, Keith, and too, it's safer to test water heater elements with electricity to the unit OFF.
The standard test of the condition of an electric water heater element is the resistance test described in the article above.
If the heating element is dead shorted out it will show continuity - that is not an OPEN circuit, it's a CLOSED one. Continuity in this case means close to zero resistance - which is not normal for a water heating element and thus would indicate trouble.
An OPEN circuit is one that is not continuous - so we would see infinite resistance. This is a more common mode of electric water heater element - the element just burns up and becomes an open circuit. Of course to avoid confusion these tests are done with electrical wires to the heating elemen t removed.
Take a look at DMM Digital Multimeter, How to Use for a nice article on how to hook up and use a digital multimeter or a VOM to check for voltage or for circuit continuity or for resistance.
Question: GE water heater flooded by Hurricane Sandy - can we just turn it back on to see if it works?
Our 50 gallon got flooded by about 2 feet of water. The lower elements got wet. is it safe to flip back on the breaker to see if by chance the heater is still working? - GE Hot water heater flooded 11/19/2012
GE hot water heater is electric, with the power coming in from the top of the tank.
GE water heater,
For details on how to get a flooded water heater back into service - if it can be re-used, see FLOODED WATER HEATER REPAIR
Questions & answers or comments about how to test the heating elements on an electric water heater.
Ask a Question or Enter Search Terms in the InspectApedia search box just below.
Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.