Where can I find reset button and is there only one reset button

1) Product warranty will be voided if you install 4500 watt elements in year-2008 model MR50238 3800 watt marathon tank.
Older 3800 watt element models have been discontinued.

2) Copy following links for Marathon resources:
http://waterheatertimer.org/Review-Rheem-Marathon-water-heater.html
http://waterheatertimer.org/How-to-replace-water-heater-element.html

3) Product warranty is voided if element wattage exceeds label on side of unit.

4) Marathon has a problem with elements burning out frequently.
To solve this problem, they suggest installing element with lower wattage, such as the 3800 watt.
Upper 3800 SP610130
Lower 3800 SP210197

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Replace heating elements can be found at amazon, click here and take a look: Amazon com rheem heating element . I hope this was helpful... cheers

If your top element is bad the the lower element will never turn on be cause the top element completes the 240 circuit. It is like a resister in a circuit. Make sure top element measures out at 13 ohms.

Problem has to be bad element or bad thermostat.

Test elements for short to ground through metal tank wall:
http://waterheatertimer.org/How-to-test-water-heater-element.html

Make sure factory-installed insulation and cover are re-installed over new thermostats so they do not misread tank temperature.
If problem does not show with elements, then replace thermostats again.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Question posted under marathon electric water heater.
Marathon is 240Volt dual element non-simultaneous water heater.
Non-simultaneous means that upper part of tank has to reach temperature before power is sent to lower thermostat and element. So if upper element is bad, then water heater has no hot water.
http://waterheatertimer.org/Replace-anode-rod.html#audibleBW

1) You need to by-pass upper element without by-passing upper thermostat.
2) You should never by-pass upper thermostat because it has ECO-reset protection.
http://waterheatertimer.org/How-water-heater-thermostats-work.html

3) Open following link for image of wiring:
http://waterheatertimer.org/images/Marathon-wiring-700.jpg
4) Take photo of your wiring in case color code is different on your specific model

5) Look at upper thermostat.
Remove yellow wire from terminal 2 on upper thermostat, and cap off temporarily.
Remove red wire from terminal 4 on upper thermostat, and move it to terminal 2 on upper thermostat.
6) For more effective operation, look at lower thermostat.
Remove black wire from lower thermostat terminal 1 and move wire to terminal 2 on lower thermostat.

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For a price, expert works with you while you work on water heater or any do-it-yourself project.
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Check 240 circuit breaker.
Open top cover on water heater and push in ECO red reset button.
If reset button will not reset, then replace thermostat.
If reset is not tripped out, then either upper thermostat is bad, upper element is bad, or water heater might be getting 120V instead of 240V.
If you have some hot water, then best suspect is lower element.
http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html

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For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

The temperature is controlled on the thermostats in the tank. They are under the two covers you see on the outside of the tank. There is an upper and lower thermostat. Make sure you shut off the power before you begin. Remove the cover and peel back the insulation covering the thermostat. Use a flat head screwdriver to adjust temp. There should be a pointer showing the temp its on now. They are probably set at 120 degrees. WARNING--turning your hot water temp above this point can cause scalding and burning in less than 3 seconds. You may have a burnt out lower element. This link below should help you

http://globalimageserver.com/fetchDocument.aspx?id=574f6c2f-32c1-4c28-824c-172bbbfe5578

This is the manual to your tank. Good luck.

You have 240Volt Marathon water heater.
These heaters have element burn-out problems.
http://www.thetankatwaterheaterrescue.com/forums/forum3/

Yes sediment can cause decreased amount of hot water when water cannot circulate around lower element, and sediment can cause lower element to burn out.
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html

Following list is overview of tank troubleshoot:

If you have some hot water, then that says several things:
-Upper element is working.
-Electricity from circuit breaker to upper thermostat is good.
-ECO reset button is not tripped.
-You do not have overheating event.
-Access doors and insulation are in place and thermostat not exposed to cool temperature that causes overheating.

That leaves following suspects:
1) Check if TP valve is stuck open, or pipe cracked, or faucet leaking and running hot water down a drain.

2) Upper or lower thermostat is bad.

3) Lower element is bad -and- maybe tank has built-up sediment
http://waterheatertimer.org/How-to-test-water-heater-element.html
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html

4) Loose wire. Open covers and inspect. Tighten screws very tight against copper wire.

5) Bad wire between upper and lower sections of tank.

6) Do complete 30 minute troubleshoot before replacing any parts.
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, fixya expert speaks with you over phone while you work on water heater or any do-it-yourself project.
We are always less expensive than a service call.

You posted under Marathon electric heater.
If you have tankless or tank-type gas heater, information below does not apply.

Absence of hot water say upper element is not working.
1) This can be caused by tripped reset button located on upper thermostat. Open upper cover and push in reset button. Put ear against tank to hear bubbly fizzing sound. Put insulation and cover back over thermostat. Continue reading information below because reset button trips when thermostats are bad or element is shorted.
2) Upper thermostat is bad. Replace upper thermostat. I usually replace both upper and lower thermostats.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
3) Electricity going to water heater from breaker box is interrupted.
http://waterheatertimer.org/Test-electricity-to-water-heater.html
4) Upper element is bad. Test element. Replace element if needed.
http://waterheatertimer.org/How-to-test-water-heater-element.html
http://waterheatertimer.org/How-to-replace-water-heater-element.html

5) Add a comment for more free help.

6) Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

Turn off the electricity.
Turn off the water valve going into tank.
Open a bathtub spout to let hot water pressure off the tank.
Check top of tank for any leaks.
Open the top access panel and see if element is leaking.
Open bottom access panel and see if lower element is leaking.
The reduced pressure on the tank will slow the leak.

If element is the problem, you can squeak by for a while by turning on the hot water heater only when you need hot water.
Order the 'Marathon MR85245 replacement element' online
http://www.gpconservation.com/rheem/marathon-sp213670-titanium-4500w-lower-element
These elements may be available locally, but they are not the same as 'ordinary' tank-type electric heater elements that you buy at the hardware store.
Buy more than 1 element because the Marathon elements have problems.
One of the reported problems with marathon elements is the high price of stainless steel replacement elements.
Drain tank.
Replace element.

Another resource for water heater information is:
http://www.thetankatwaterheaterrescue.com/forums/forum3/