GE40M06AAG lower element leaking at the gasket. Will any 240V, 4500W replacement element work, or is there one recommended?

Rheem has a tool for you to test theories like this. It is being overhauled

https://www.rheem.com/residential-water-heater-product-cross-reference/

Yes, your element is discontinued.

https://www.searspartsdirect.com/model/1pmpqe6ok1-001299/rheem-81v52-electric-water-heater-parts

Here is the one you are considering. At 1,000 watts less, it will just take a little longer to recover. Phone them, as to speak to someone in the Service Department. They will know. You know we aren't them? We just have a category here at Fixya.

https://parts.rheem.com/product/RPD-SP20060

..

you can its your water heater , but the heating elements are sized to tank.. Stay with original specs The electrical may be to small for the additional power requirments

Yes
Voltage and wattage printed is on end of each element
If element shows 240V 4500 watt, then element Wattage at 208V is reduced to 3375 watts and will heat 16+ gallons per hour
If element is rated 208 and 4500w, then element will operate at 4500 watt and heat 20 gallons per hour
http://waterheatertimer.org/Figure-Volts-Amps-Watts-for-water-heater.html

http://waterheatertimer.org/images/Whirlpool-energy-smart-watt-rating-IMG_2600.jpg

http://waterheatertimer.org/How-to-replace-water-heater-element.html

Gene

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

1) Manufacturer's warranty will be voided, and I've never seen recommendation that suggests better heating or saving money from replacing 4500W with different wattage element.

2) That being said, you have 240V water heater.
4500Watts divided by 240 = 18.75 amps
5500Watts divided by 240 = 23 amps

20 amp circuit breaker with 12 gauge wire is rated for 80% of load = 16amps
30 amp circuit breaker with 10 gauge wire is rated for 80% of load = 24amps.
http://waterheatertimer.org/Figure-Volts-Amps-Watts-for-water-heater.html

3) You can use 5500Watt element if you have 30 amp breaker and 10 gauge wire.

Sounds like you might have a thermostat problem, or burned out lower element
Lower thermostat and both elements will test for 120V at all times because upper thermostat only cuts off one leg of 240V circuit, and other leg is hot all the time.

http://waterheatertimer.org/How-to-test-water-heater-element.html
http://waterheatertimer.org/How-water-heater-thermostat-works.html
http://waterheatertimer.org/How-to-wire-water-heater-thermostats.html
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

Yes, the elements alternate being turned ON.
This is called non-simultaneous operation.
Look at label on side of tank: Each element has rating of 4500Watts, but tank rating is also 4500Watts > that shows that both elements are not ON at same time.
This is standard wiring for water heaters.
http://waterheatertimer.org/How-it-works.html

Water heaters can we wired differently, for example converted to simultaneous operation where upper thermostat and lower thermostat are no longer wired together, so upper and lower parts of tank are independent.
Lower thermostat is replaced with ECO protected thermostat identical to upper thermostat.
Another 240V circuit breaker is added to breaker panel, and that 240V line runs directly to lower thermostat. So upper and lower thermostats are each on separate 240V line.
The advantage of simultaneous is faster recovery of hot water, but downside is probably higher electric bill. Simultaneous wiring is usually reserved for larger tanks like 80 gallons, where elements can fall behind the amount of hot water needed.
Otherwise, ordinary non-simultaneous operation is proven to be satisfactory, if your home has not experienced shortages.
http://waterheatertimer.org/B220C.html
http://waterheatertimer.org/How-to-wire-off-peak-water-heater-thermostats.html
http://waterheatertimer.org/Do-it-yourself-water-heater-timer.html

Add a comment for more free help.

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

You need to take 1/2 hour to learn basics and then test water heater parts before replacing anything.
http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html
Follow the troubleshooting steps, and it will tell you exactly where the problem is.
Otherwise we can guess at 20 different things.

Water heater is 240V because you have more than 1 element.
Did you test for 240V across top two screws of upper element?
Breaker can be tripped off on one leg and 120V arrives at water heater so heater looks like it has electricity, but circuit is not complete.

The problem can be loose wire, bad 240V circuit breaker, sediment reaching lower element, bad thermostat, bad upper element, tripped ECO reset button.

Did you replace factory insulation and cover over thermostats after replacing elements?
Did you vacuum out sediment when replacing lower element?

How long ago did you replace elements? If you turned power ON before tank was completely filled with water, then you burned out the element. If upper element is burned out, the tank has no hot water, even if lower element is good.
Test the upper element:
http://waterheatertimer.org/How-to-test-water-heater-element.html
See how a water heater works:
http://waterheatertimer.org/How-it-works.html

And finally, why so many folks write to fixya saying they replaced both elements and upper thermostat, but they never replace lower thermostat for another $6? I have been puzzled about that since lower thermostat turns on and off each time tank temperature drops and is responsible for keeping water warm during standby hours. Lower thermostat cycles more times than upper thermostat.

Add a comment if you need specific assistance with any of the testing steps.

Either element will work ... straight or bent.
4500 Watt element will work, buy you can also substitute 3500, or 1500 Watt.
Stepping up wattage larger than water heater nameplate is not recommended, because wiring may not carry more watts.

Element wattage is printed on end of each element.

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

Reliance 501 manual is not available on Reliance site.
The 501 used to be standard model, but now it's the 600 series.
http://www.reliancewaterheaters.com/prod/elec.html

600 series manual is similar to your product.
page 22 shows element replacement, and says not to use greater wattage than rating plate on water heater.
http://www.reliancewaterheaters.com/lit/om/manuals/185761-000.pdf

Age of Reliance heater is on serial number. First character is letter. Next two characters are numbers corresponding to year. So C05222,,, serial number is made in 2005.

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/

If original problem was caused by sediment burning out lower element, did you clean sediment out of water heater when changing lower element?
Two element water heaters are 240V.
Thermostats cut power on one hot wire, but 240V circuit has 2 hot wires. So lower element has power at all times coming from the red wire.
1) Use ordinary tester or multimeter set to 240V <> test each screw of lower element to bare metal part of water heater. Each screw should show 120V. If there is no power, then upper thermostat is defective, screw on upper thermostat is loose, or red wire between upper and lower parts of water heater is bad.
2) Remove wires from lower element. Use continuity tester or multimeter set to ohms <> test across both screws of element to see if power travels through element <> if element is bad, then continuity tester will not light up and multimeter will show no ohms. Put wires back on element after test.
3) Start with cold water in tank. Turn on water heater & upper element will turn on. Put ear on side of tank to hear if upper element is heating water. Test #3 screw to #2 screw on low left side of thermostat, should read 240V > Test #3 screw to #4 screw on low right side of thermostat, should read 0V.
Put ear on side of tank. When upper element turns off: Test #3 screw to #2 screw on low left side of thermostat, should read 0V > Test #3 screw to #4 screw on low right side of thermostat, should read 240V. If this test shows 0V and 0V, then upper thermostat is bad. If reading is correct, immediately move to next test.
http://waterheatertimer.org/images/Thermostats-numbered-divided-500.jpg
4) Turn temp on lower thermostat to 150. Using ordinary tester or multimeter set to 240V <> Test across both screws of lower element. If there is no reading, and you know element is good from step 2, then lower thermostat is bad, or wire is bad between lower element and lower thermostat, or wire is bad between lower thermostat and top part of heater.
5) Test across both lower thermostat screws, should read 240V.If this test is good, it means wires are good. Put jumper wire across both screws of lower thermostat, and test lower element again. If element finally turns on with jumper wire, then lower thermostat is bad.
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http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html

If wire is bad between upper and lower parts of water heater, and water heater has tight-fitting 2" foam insulation, it usually indicates water heater replacement.

did you turn the power on BEFORE you filled it with water???

this is a pretty common mistake. you will need to check the upper element to make sure its working.
most water heaters have an upper and lower themostat. the upper thermostat is the one we need to check.

use your volt meter...

turn the power off, test with your volt meter to make sure! remove one wire from the element, not the thermostat, and check resistance on the element. if no resistance, you burned the element, and will need to replace it.
replace with same wattage, usually 4500watts. it will be written on the element.
also, I like to push the reset button on the thermostat to make sure it wasn't tripped.