is a self-help website
Figure volts amps watts for water heater 9 Ways to save with a water heater Do-it-yourself
See new water heating ideas 2010
2014                                                                         How to find age of water heater

How to test water heater element

Power is OFF during this test
How electric water heater works
How to replace water heater thermostat
How to replace element and clean tank
How to remove rusted element
How to troubleshoot electric water heater parts
How to wire water heater thermostats

Buy multimeter for $10 at local box
Install battery.
Rotate dial to 240-250Vac to test for electricity.
Rotate dial to Ohms to test element as shown on this page.
(upside down horseshoe symbol is ohms)
Multimeters at Amazon

Buy inexpensive multimeter

1) Use multimeter to test element
2) Do not drain water heater
3) Power is OFF during this test.

Multimeters at Amazon

How to troubleshoot electric water heater

See ohm chart

Volts squared divided by watts = ohms.
Watts are printed on end of each element.
All 2-element tanks are 240volts.
220 Volt circuit breaker

Turn off circuit breaker

Turn off 30 amp double breaker to 240Volt heater
Turn off 20 Amp single breaker to 110 Volt heater

Voltage and wattage of water heater is printed on label located on side of tank. Take photo of label for your records.

See basic water heater circuit
water heater element
Recommended: Use non-contact voltage tester.
Touch end of tester to each black, white, and red wire. Press button. If tester flashes repeatedly like alarm, then voltage is present. if tester flashes once, then that says it is testing and no voltage is present.
Buy non-contact voltage tester at Amazon

Test for electricity

Use 120V/240V tester or use multimeter for this test

Open cover on top of water heater
 Use non-contact voltage tester on electric wires at top of tank, and at each element and thermostat
Advantage of this tester is safety since wire nuts are not removed

120V and 240V. Test Black to Ground, test Black to White, test White to Ground. If tester light comes on, electricity is present  
Test water heater
Larger image
Shop Amazon Tools - Over 50 Off DEWALT Tools
Shop Amazon Tools - Over 50 Off Black and Decker
Shop Amazon Tools - Over 25 Off Stanley Tools
water heater thermostats

Open panels on side of water heater

Do not drain water heater to test elements

Older water heaters have fiberglass insulation covering element and thermostat. This insulation is removeable, and must be put back when finished.

Newer water heaters have tight-fitting foam insulation.
Foam insulation is not easy to work around. You may need to cut back the foam to work on parts. Remove as much foam as needed to access parts.When finished, parts must be covered by insulation again or thermostats are exposed to cool air and will misread tank temperature
Water heater insulation
Larger image

Which element do you test?

If water heater makes some hot water, then lower element is suspect.
If upper element is burned out, water heater will have no hot water.
If water heater is tripping circuit breaker, then test both elements and look for burned and melted wire.

What to do if melted/burned wire is found

Troubleshoot electric water heater
How water heater works
How to wire thermostats
Test electricity to water heater

Element burns out
Tank must be full of water or elements burn out

Newer tanks have foam insulation

Older tanks have fiberglass insulation
remove wires from elelment

Take wires off element

Use nose and eyes to inspect

for burned/ melted parts and wires.
If wires are burned/ melted then replace part and test wire for continuity.
water heater element
Bolt-in and screw-type elements
Water heater elements at Amazon
Low density element at Amazon

Test element
Set multimeter to read ohms

Rotate dial to Ohms to test element
Ohms is upside down horseshoe symbol
Multimeters at Amazon

Good element passes 3 tests:

Test 1: Element shows correct ohm reading
Test 2: No reading on multimeter
Test 3: No reading on multimeter

Rotate dial to Ohms to test element
Water heater element
Larger image
test element

Test 1:

Test across both element screws and resistance should read about 12.8 Ohms for 240-Volt 4500-Watt element. For 30 gallon tank with 3500-Watt elements, reading is about 16 Ohms. See ohm chart

Open reading means element is bad. No reading means element is bad.
Element wattage printed on each element
Test voltage
Element wattage      volts                     ohms
3500 watt                 240                       16
4500 watt                 240                       12-13
5500 watt                 240                       10-11

'Volts squared' divided by watts = ohms
Volts x volts is 'volts squared'
240 volts x 240 volts =  57,600
57,600 divided by 4500 watt = 12.8 ohms
See ohm chart
test element 2

Test 2:

Test each screw to bare metal part of water heater.
Test both screws.
If multimeter reads any Ohms at all, or if needle moves even tiny bit, then element is shorted and needs replacement see how
Test element 3

Test 3:

Test each screw to metal base of element.
If multimeter reads any Ohms at all, or if needle moves even tiny bit, then element is shorted and needs replacement

- Results -

Elements are good

Double-check results before putting wires back on elements.
If elements burn out frequently, then install lower wattage element.

But still not working

Troubleshoot walk-thru
Melted wire

Element has burned wire

Replace element
Test wire for continuity

Element is bad

How to replace element
Full efficiency can be restored to electric heater

Water heater must be empty before element is removed
Water heater elements at Amazon
Low density element at Amazon

Element wrench
Leave water heater full of water to loosen element
Then drain water heater and remove element
Water heater element socket 1-1/2" at Amazon
Camco heavy duty element socket
Marathon elements are 1-7/8"
remove old water heater element

Element will not come out

How to remove rusted element
Drill, tap and use bolts and wrench to remove.
Drain water heater before drilling into element
Prevent rusted water heater.
Anode rod is necessary so tank will not rust.
Anode rod depletes and should be inspected 1-3 years with water softener, and 2-5 years otherwise.

Loosen anode rod before draining tank so weight of water helps hold tank steady
How to replace anode rod
clogged water heater

Water heater will not drain

Do not drain water heater to test element.
Water heater is drained only when replacing element

Water heater will not drain
Use household water pressure and washing-machine hose to flush open water heater for 5-10 seconds
Water heater cover
Larger image

Re-install insulation over thermostat and element

 Caution: Insulation and cover must be re-installed or thermostat is exposed to cooler air and will misread tank temperature.

How to replace water heater thermostat
Shorted element
Larger image

ECO reset button keeps tripping

or circuit breaker keeps tripping: element shorted to ground across steel tank
What happens:
- Illustration shows why element-test requires testing between element screws and steel tank
- 240Volt water heaters have 2 Hot wires. Each hot wire is called a leg. Each leg is 120Volts with 240Volt potential when both legs are connected together. Difference between 120Volts and 240V
- Thermostats turn off one leg in the 240Volt circuit.
- When thermostat turns ON, that event connects the second leg to the first leg, and element turns ON.

- In some cases, the element can crack or short. In most cases, the short will trip circuit breaker.
- If the crack or short is far enough along in the element, the resistance will not cause breaker to trip. The short travels across steel tank hull to the ground wire at top of tank.
- The ground wire will complete 120Volt circuit. Elements will heat up using 240Volts or 120Volts. Element continues heating, and will not turn off. This causes runaway heating, and TP valve will release water or ECO reset will trip.
How to convert water heater to 120volts
Elements burn out frequently
Larger image

Elements burn out frequently: install lower wattage element, or install low watt density element

Causes include:
a) Sediment in bottom of tank   How to replace element and clean out sediment.
b) Very hard water. Install softener. Read about softener and anode depletion
c) Watt densitiy of element too high. Change element. Install element with less than 3800 watt See image  Read pdf
d) Agressive high pH water. Test water.
e) Loose wire on element. Open covers and inspect all wires for loose connections and signs of burning.
Read more about elements
Water heater formulas and terminology pdf

Water heater elements at Amazon
Low density element at Amazon
High density element
Low density element
Screw-in elements

Breaker keeps tripping

Read more:
Circuit breaker keeps tripping
New water heater not working

Lower energy bill $10 per month

Maintain water heater pays $10 per month
How to maintain water heater
    1)  Read about anode rods
    2)  Read about stray current corrosion
   3)  How to clean sediment out water heater
How to flush water heater/ steps
    5)  9 ways to save with water heater

Flush each 6 months
Inspect for leaks each 6 months
Check and replace anode rod each 1-3 years
Troubleshoot resources for electric
Troubleshoot resources for gas
Safety precautions
Read and save product manual
More Do-it-yourself resources

Don't buy tankless: pro-n con
Troubleshoot tankless water heater
flooded water heater
Flooded water heater
Should be replaced

water heater anode rod
How to replace anode rod
Anode rod prevents tank from rusting.
Test and replace TP valve
How to test and replace TP valve
Lift lever and gently lower once each year.
Water heater drain valve
How to repair/ replace water heater drain valve
Put garden hose cap over dripping drain valve.

Do not cap TP valve.

Additional links

See basic water heater circuit

Electricity from pole to breaker box
How to install gas water heater
How to install gas water heater

Figure volts amps watts for water heater

Compare all water heater timers

240 V Intermatic water heater timer
Compare box timers
Compare box timers

How to Install subpanel
Leaking water heater
Troubleshoot leaking water heater

How to install gas water heater

How to wire off-peak water heater
Off-peak water heater ideas
Solar water heater
9+ ways to save with water heater

Low hot water pressure
Put pressure gauge on tank drain
Buy Rainbird at Amazon
Buy BTG 100 at Amazon
Safety Equipment for Professionals
Industrial and scientific Amazon

Remove water heater from attic
Empty water heater weighs 75-100 lbs

Compare water heater timers

Troubleshoot gas water heater

Bath uses 12-15 gallons hot
Shower uses 5-9 gallons hot

Save 10 gallons hot water exh time by taking shower instead of bath

Difference between 120 and 240
Three phase timer & wiring

How to wire switches

Intermatic timers / manuals


Two water heaters

Install subpanel

Gas control valves
Gas and electric water heaters Support the economy:
Buy water heaters  from my associate links:

50 gallon Gas water heaters at Amazon
40 gallon gas water heaters at Amazon
50 gallon Electric water heaters at Amazon
40 gallon electric water heaters at Amazon
Hybrid / heat pump/ water heaters at Amazon

How to install gas water heater
Troubleshoot gas water heater
Troubleshoot electric water heater

E-mail: geno03245w@gmail.com
My response might end up in spam folder, check email folders
Site map
Follow newest idea on twitter
Privacy policy