test water heater element
Test elements
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How to test water heater element


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.

Buy:
Multimeters at Amazon
hhhh

Resource:
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
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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
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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
Buy:
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.

Elements good but water heater still not working

Push breaker fully off and then fully on
Tank heats 21 gallons per hour
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
Buy:
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
Buy:
Water heater element socket 1-1/2" at Amazon
Camco heavy duty element socket
Marathon elements are 1-7/8"

Buy from my links

  $25 - $47
Ultra low watt density
5 year warranty
Ultra Low Watt Density/ ripple
Hard water element
Resists high mineral count
Minimum 15" diameter tank
Buy 240 volt from my associat links:
4500 watt at Amazon
4500 watt at Amazon 13" diameter
5500 watt at Amazon
Camco elements at Amazon
$13 - $26
Ultra low watt density
5 year warranty
Ultra Low Watt Density/ foldback
Hard water element
Resists high mineral count
Check minimum tank diameter
Fits any tank above minimum dia
Buy 120 volt
1500 watt 120 volt 8" minimum
Buy 240 volt:
2500 watt at Amazon 
3500 watt at Amazon
4500 watt at Amazon
5500 watt at Amazon
$10 - $16

Low watt density
Camco/ no extended warranty
Low Watt Density/ foldback

Check minimum tank diameter
Fits any tank above minimum dia
Buy 240 volt:
2500 watt at Amazon
3500 watt at Amazon
4500 watt at Amazon
4500 watt 12 pack
5500 watt at Amazom

6000 watt at Amazon
$10 - $12
Low watt density
Camco/ no extended warranty/
High Watt Density
Standard on all new water heater
Can use foldback as replacement
Match volts and watts
Buy 240 volt
1500 watt at Amazon
2000 watt 12 pack
2500 watt at Amazon
3000 watt at Amazon
3500 watt at Amazon
3800 watt at Amazon
4000 watt at Amazon
4500 watt at Amazon
4500 watt 12 pack
480 volt element
Larger image
Volts and watts are printed on end of each element
Volts and watts are printed on end of each element
480 volt 4000 watt
or
415 volt 3000 watt
When voltage drops, the element wattage also drops

Typically 480 volt is common on 3-phase non-balanced commercial water heaters. The non-balanced 3-phase heater can be converted to single phase but attention must be paid to the element voltage and wattage
Resource: 3-phase non-balanced / and conversion to single phase

How to figure resistive wattage by volts

Ohm's laws says: Volts squared  watts = ohms  Resources: See chart   How to test element
Each element has volt and watt rating printed on end of element
If element is rated 4500 watts @ 240 volts.... then volts squared (57600)
4500 watts = 12.8 ohms
So 12.8 is the ohm rating for the element, no matter what voltage is applied

But what happens when voltage is reduced on the same element?? For example voltage is reduced to 208 volts instead of 240 volts.
Then 208 volts squared (43264) 
12.8 ohms = 3380 watts... and the element does not burn as hot

What happens when voltage is reduced to 120 volts on same element?
Then 120 volts squared (14400)
12.8 ohm = 1125 watts and heating is reduced to 1/4 the original output

What happens when voltage is reduced on 480 volt, 4000 watt element?
480 Volts squared
(230400) 4000 watts = 57.6 ohms/ and 57.6 is the ohm rating for element no matter what voltage.
So when voltage is reduced to 415 volts:
415 volts squared
(172225) 57.6 ohm = 2990 watts (or 3000 watts as shown in photo)

What about increasing voltage instead of lowering voltage?
What happens when 480 volts is connected to element that is rated for 4500 watts and 240 volts? POW ! element burns out
480 volts squared (230400) 
12.8 ohm element = 18,000 watts or 4 times the rating... and the element will butn out immediately

What happens when 240 volts is connected to element that is rated for 2000 watts and 120 volt? POW again
120 Volt squared (14400) 2000 watts = 7.2 ohm
240 volts squared (43264) 7.2 ohm element = 6000 watts running through a 2000 watt element causing it to burn out

So buy element that is rated for the voltage  Resource: Elements and element replacement
High density element
Low density element
Screw-in elements

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.
Resource:
How to replace elements
Water heater formulas and terminology pdf

Buy:
Water heater elements at Amazon
Low density element at Amazon
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
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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
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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

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
   4)
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
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Compare box timers

How to Install subpanel
Leaking water heater
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How to install gas water heater

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Off-peak water heater ideas
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9+ ways to save with water heater

Low hot water pressure
Put pressure gauge on tank drain
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Empty water heater weighs 75-100 lbs

Compare water heater timers

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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


Stacking

Two water heaters

Install subpanel

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

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Resources:
How to install gas water heater
How to install electric water heater
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Troubleshoot electric water heater
Point of use water heaters
Gas and electric water heaters Industrial electric at Amazon

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box timers Compare box timers

Control water heater w/ Z-wave
Intermatic control centers Control centers:
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All control centers and parts

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programmable timer Compare programmable timers

Control water heater with programmable wall timer
Countdown timers Compare countdown timers

Control water heater with countdown timer
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