Can a single element water heater be controlled with a multi-element thermostat?

Why Does My Electric Water Heater Reset Button Keep Tripping? So the red reset button on your electric water heater keeps popping out and needing to be reset.
Here's the most likely problem: The water in your water heater is getting too hot.
When the water temperature in your water heater exceeds 180°, the red reset button (also known as the high-limit switch) trips. This tripping protects you from getting scalded or burned when using hot water in your home.
OK, but then what's causing the water in your water heater to get so hot? The most likely cause is a bad thermostat.
How a bad thermostat causes your water heater reset button to trip Electric water heaters have a lower and upper thermostat-one for each heating element.
The thermostats are responsible for controlling the heating elements. When the water has cooled off, the thermostats kick on the heating elements to heat the water. And once the water has reached your desired temperature, the thermostats shut off the heating element.
(This is very similar to the way your heating and air conditioning thermostat controls your home HVAC system.)
But these thermostats can go bad. When they do, they sometimes get stuck in the "on" position. This means that that the heating element continues to heat your water, eventually causing the high-limit switch to trip.
The fix: The bad thermostat needs to be replaced. A plumber can use a multimeter to test the thermostats and find out which one is bad.
Other problems that can cause your high-limit switch to trip While a bad thermostat is the most common reason your water heater's reset button may trip, it's not the only one. Other common causes include:

• A shorted heating element-It may be that the thermostat is working just fine and shutting off the heating element. But a short in the element is causing it to continue to heat your water.
• Loose wiring-A loose wire in the water heater can generate heat that can cause the high-limit switch to trip.
• Bad high-limit switch-The switch itself may be malfunctioning and tripping when it shouldn't be.

Get a professional plumber's help

Do you live in the Minneapolis-St. Paul area and need a reliable plumber to help you troubleshoot your water heater problem? Contact MSP Plumbing. We can usually fix the problem the same day.

probably not right as there is only one thermostat control normally
duel elements are used to heat the water faster for recovery as the same size element in single use would be too big to fit in the unit

If water heater thermostat is bad, buy a generic thermostat at hardware store and install it according to instructions shown on link below:
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
I usually replace both upper and lower thermostats for about $28.
Lowes sells thermostats and elements.
If your water heater is a single-element/ single-thermostat, you can buy any thermostat with red reset button.
Technically a single-element thermostat has 1 less screw, but either thermostat will work.
If your water heater is 120V or 240V, the same thermostat will work of either voltage.
This is true because the thermostat is a simple bi-metal heat-reading device that does not operate on electric current.

That being said, you might want to test parts before replacing anything, in case problem is element.
To do comprehensive electric water heater troubleshoot:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

Image below shows generic thermostat with reset button. Each of these will work for single-element or dual-element tanks with either 120V or 240V. Wires connect just as they did on old thermostat. Tighten wires very tight. Press in reset button to make sure ECO is set. Put insulation and cover back over thermostat when finished.

You have electric water heater.
Electric water heaters are fully repairable by homeowner, excluding hybrid type.

Rheem electric water heaters:
http://www.rheem.com/products/tank_water_heaters/electric_water_heaters/
Rheem fury series manuals and models
http://www.rheem.com/product.aspx?id=09DF2BDD-5E11-4D32-B574-84ACFB8A4619

Age of Rheem water heater is shown first 4 digits of serial number located on side of tank: for example 0705 means July 2005.
Serial number also shows model number & wattage of elements in case you need to buy new generic 4-bolt type 4500 Watt element from hardware store.

A) If your water heater receives very cold incoming water, it may not heat fast enough to keep tank warm.
Add a tempering tank.
http://waterheatertimer.org/Tempering-tank.html
Add insulation over entire water heater except TP valve. Insulate pipes completely.
Read more information:
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html

B) 40 or 50 gallon water heater is 240Volts and tank will have 2 access panels on front.
Rheem ships all water heaters with 4500 Watt elements.

Narrow down the suspects:
C) Water heater has some hot water.
This tells us upper element is working.
And that water heater electricity is working.
And that reset button is not tripped.
And that heater is not experiencing run-away overheating event.

That gives us 3 solid suspects.
1) lower element is burned out. Test lower element using inexpensive multi-meter from Home Depot.
http://waterheatertimer.org/How-to-test-water-heater-element.html
Replace element with same wattage shown on label, and clean out sediment:
This will restore water heater to full 99% efficiency.
http://waterheatertimer.org/How-to-clean-sediment-out-of-electric-water-heater.html
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html

2) Upper or lower thermostat is bad. Replace both thermostats for about $25.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
If you want to test thermostats and all parts before replacing anything:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

3) Burned or shorted wire. Turn off power. Open covers on side of tank. Remove insulation. Inspect parts for signs of high heat and burning. Especially lower element. Tighten any loose wires. Replace part that shows signs of burning.
Put insulation and cover back over thermostats so cooler outside temperature doesn't cause thermostat to misread tank temperature.

Rheem 4500 watt element

You have electric water heater.
Electric water heaters are fully repairable by homeowner, excluding hybrid type.

Rheem electric water heaters:
http://www.rheem.com/products/tank_water_heaters/electric_water_heaters/
Rheem fury series manuals and models
http://www.rheem.com/product.aspx?id=09DF2BDD-5E11-4D32-B574-84ACFB8A4619

Age of Rheem water heater is first 4 digits of serial number located on side of tank: for example 0705 means July 2005.
Serial number also shows model number & wattage of elements.

A) If your water heater receives very cold incoming water, it may not heat fast enough to keep tank warm.
Add a tempering tank.
http://waterheatertimer.org/Tempering-tank.html
Add insulation over entire water heater except TP valve. Insulate pipes completely.
Read more information:
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html

B) If cold outside temperatures are not to blame, your water heater may have a bad thermostat or bad lower element.

C) 40 or 50 gallon water heater is 240Volts and tank will have 2 access panels on front.
Rheem ships all water heaters with 4500 Watt elements.

Narrow down the suspects:
D) Water heater has some hot water.
This tells us upper element is working.
And that water heater electricity is working.
And that reset button is not tripped.
And that heater is not experiencing run-away overheating event.

That gives us 3 solid suspects.
1) lower element is burned out. Test lower element using inexpensive multi-meter from Home Depot.
http://waterheatertimer.org/How-to-test-water-heater-element.html
Replace element with same wattage shown on label, and clean out sediment:
This will restore water heater to full 99% efficiency.
http://waterheatertimer.org/How-to-clean-sediment-out-of-electric-water-heater.html
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html

2) Upper or lower thermostat is bad. Replace both thermostats for about $25.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
If you want to test thermostats and all parts before replacing anything:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

3) Burned or shorted wire. Turn off power. Open covers on side of tank. Remove insulation. Inspect parts for signs of high heat and burning. Especially lower element. Tighten any loose wires. Replace part that shows signs of burning.
Put insulation and cover back over thermostats so cooler outside temperature doesn't cause thermostat to misread tank temperature.
Rheem element

You have electric water heater.
Electric water heaters are fully repairable by homeowner.

Reliance is AO Smith company
http://www.aosmith.com/OperatingUnits/Detail.aspx?id=138&ekmensel=c580fa7b_12_0_138_3
http://www.reliancewaterheaters.com/prod/elec.html

Age of Reliance water heater is shown on serial number located on side of tank: first digit is letter. Next two digits are numbers: for example C06 means 2006.
Serial number also shows model number & wattage of elements in case you need new element from hardware store.

A) If your water heater receives very cold incoming water, it may not heat fast enough to keep tank warm.
Add a tempering tank.
http://waterheatertimer.org/Tempering-tank.html
Add insulation over entire water heater except TP valve. Insulate pipes completely.
Read more information:
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html

B) If cold outside temperatures are not to blame, your water heater may have a bad thermostat or element.
Narrow down the suspects:

Water heater is 240Volts since you have more than 1 thermostat.
Water heater has some hot water.
This tells us upper element is working.
And that water heater electricity is working.
And that reset button is not tripped.
And that heater is not experiencing run-away overheating event.

That gives us 3 solid suspects.
1) lower element is burned out. Test lower element using inexpensive multi-meter from Home Depot.
http://waterheatertimer.org/How-to-test-water-heater-element.html
Replace element with same wattage shown on label, and clean out sediment:
This will restore water heater to full 99% efficiency.
http://waterheatertimer.org/How-to-clean-sediment-out-of-electric-water-heater.html
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html

2) Upper or lower thermostat is bad. Replace both thermostats for about $25.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
If you want to test thermostats and all parts before replacing anything:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

3) Burned or shorted wire. Turn off power. Open covers on side of tank. Remove insulation. Inspect parts for signs of high heat and burning. Especially lower element. Tighten any loose wires. Replace part that shows signs of burning.
Put insulation and cover back over thermostats so cooler outside temperature doesn't cause thermostat to misread tank temperature.

If I understand correctly the red reset button or ECO located on upper thermostat will not reset.
Add a comment if problem is different.

Electric water heaters are fully repairable by homeowner.
If circuit breaker to water heater will not reset, then you need full troubleshoot using inexpensive multi-meter from Home Depot::
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

If reset button will not reset, then two things can cause this problem.
1) Ground short between upper thermostat and upper element, including shorted upper element.
a) Look at wires to see visible signs of high heat and burning.
b) Test upper element for short.
http://waterheatertimer.org/How-to-test-water-heater-element.html

2) Upper thermostat is bad. Test upper thermostat, or just replace thermostat using generic upper thermostat from hardware store.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

3) If problems persist:
Troubleshoot electric water heater using inexpensive multi-meter from Home Depot:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html


Upper thermostats are generic unless you have "energy-smart" water heater that has control box and reset button located on top of tank.

Lower element can be burned out and still read 230V across screws

1) We know thermostats are working because elements test 230V.
2) We know upper element is working because tank has some hot water.
If upper element is burned out, tank will have no hot water.
http://waterheatertimer.org/How-it-works.html

3) Here's how to test lower element:
http://waterheatertimer.org/How-to-test-water-heater-element.html

4)Here's how to replace element
Rheem element is 4500Watt bolt-in type
http://waterheatertimer.org/How-to-clean-sediment-out-of-electric-water-heater.html

5) Rheem manual says: Heaters furnished with standard 240 volt AC, single phase non-simultaneous wiring, and 4500 watt upper and lower heating elements.
http://waterheatertimer.org/pdf/Rheem-spec-sheet.pdf

Rheem 4500Watt element

You say the hot water runs out after one shower.
You posted under electric heater.

In case you have a gas heater:
With gas heater, the flame quality could be bad because of restricted air flow or dirty burner, the control valve and thermostat could be bad, the air intake could be clogged, or the water heater is full of sediment and the flame is burning all the time and unable to heat much water.

With electric heater, the lower element is probably burned out and bottom filled with sediment, but thermostats could be bad, or you could have shorted wire.

Narrow down the suspects
If water heater makes some hot water then upper element is working.

Three remaining suspects are upper thermostat, lower thermostat, lower element, and possibly a loose wire

Check screw terminals for signs of burning and loose wires. Especially check lower element.

Let's test lower element.
Turn off power.
Remove both wires from lower element.
Test across both screws with a continuity tester.
Continuity tester is available at hardware store, or you can make one with battery, wire and a flashlight bulb.

The continuity tester has a battery and when light comes on, it says the circuit is complete.
Test1) Test across both screws on lower element with continuity tester.
If light comes on then element is good, but element has to pass one more test.
Test2) Test each screw on element to any bare metal part of water heater.
If light does NOT come on with second test, then element is good.
Light ON first test. Light OFF second test. Then element is probably good. But test is not fail-proof without using a meter.

I'm betting the lower element is burned out and you need to replace lower element. And you may need to vacuum out the sediment.
http://waterheatertimer.org/How-to-clean-sediment-out-of-electric-water-heater.html

Now if lower element is good, then the easiest thing is to do is replace both thermostats. Buy generic thermostats at hardware store for $25. After replacing both thermostats, the water heater will probably work. If there is still a problem, then the lower element was not as good as test showed, and it should be replaced also.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

If you are still having a problem, answer back and we'll give more details.

'Rheem 81VP15S point of use' is a single-element, 15 gallon, 120V electric.
Other 'point-of-use' sizes range from 2-1/2 to 6 gallon to 20 gallon.

Electric water heaters have 2 parts: thermostat and element. One is not functioning correctly. Most likely the element caused by sediment build-up.

How to determine if tank has element or thermostat problem:
Do not turn off water going into tank. Put hose on drain valve. Open drain valve. Does water come out like open spigot? If water does not flow, then heater is likely clogged with sediment.

Solution 1: If water flows out like a spigot, the thermostat is probably bad. Read: How to replace thermostat.

Solution 2: Water does not flow, so element is surrounded by sediment build-up and cannot heat water. You need to clean out tank with shop vac, and put in new element ... plan full day and 3 trips to hardware store. Simply draining tank will not remove sediment. Sediment is chunky and will not come out voluntarily.

Buy element before starting:
-Turn off electricity
-Open cover on side of tank, remove insulation (these have to be put back for proper operation of thermostat)
-The are 2 electrical parts >>the element and the thermostat which is located above element
-Element wattage is printed on element and also shows on label on side of tank
-I think Rheem element is held in place with 4 hex bolts
-Take photo of element to hardware store so you have part on hand before removing old element
-If element is 1-1/2' diameter hex type, you need inexpensive element wrench from hardware store + the element

Drain tank and clean sediment:
-Read: To open drain on water heater so water comes out
-Read: How to clean sediment out of water heater