All the parts are working 100%,but jacuzzi trips the earth leakage after 2 hours

Hi, I suppose that you talk about an electric geyser.
It is important to know if tripping is the result of a shortcut or via the earth leakage switch.
In the fist case, often insulation is somewhere gone.
But more likely is the second possibility.
then there can be somewhere a little leak in the water circuit and condensation goes on the wires and they become conductive to small currents, specialy to the earth wire.

Is their not two elements, one at the top too? If it is tripping on the high limit switch it could be the thermostat Try checking the grounding of the unit.

. http://en.wikipedia.org/wiki/Residual-current_device

Bad thermostat
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

If problem continues, replace elements
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

There is a ground fault somewhere...you need to isolate it with an ohm meter.

What is the problem you afe having with your Jacuzzi Water Heater?
Is this a Jacuzzi Hot Tub?-- Do you have some indicator lights on?-- what color are the lights?--
Is the Circulating pump running water thru the heater element?
Tell me more!-- Let's walk thru the system, and figure it out-- Mack B

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.

The Rheem water heater uses 4500 Watt elements
Check label on side of any appliance to see electrical rating details
2 element tank with two 4500 watt elements is still a 4500 watt appliance since both elements are never ON at same time.

Volts x amps = watts
amps = watts divided by volts

amps = 4500 divided by 240Volts or 220Volts
amps = 18.75
Your water heater uses 18.75 amps to 20.45 amps

Your 25 amp breaker should only carry 80% of rated value
25 amps x 80% = 20 amps.

So your water heater breaker is correctly sized.
You should have a 10 gauge wire going to this water heater.
12 gauge wire is a bit undersized for 4500 Watt water heater
Feel the water heater wire to see if it is warm.

If the main breaker is getting hot when 20 additional amps are being used by the water heater.
1) The house is using more amps than your 100 amp main can carry
Using the formula, 100 amps x 80% = 80 amps for the main breaker
Add up your total amp draw.
For example if your 3500 watt oven is ON, it draws 16 amps.
If your 5000 Watt electric heater is on, it draws 23 amps.
Your 1500 Watt 120V microwave draws 12.5 amps.
Add these numbers up plus your water heater, and it comes to 71 amps.
71 amps is getting close to the max 80 amp, but it's not over.
Now if you have a pool pump and and hot tub and a table saw going, the main breaker could be overdrawn.

2) To solve the problem short-term, you can put a timer on the water heater and use it only when needed.
http://waterheatertimer.org/Compare-13-electric-water-heater-timers.html

3) The main breaker is bad and needs to be replaced.

If you need help figuring circuits or timers, add a comment and I will help

The reset button or ECO (emergency cut-off) is a safety device.
The ECO trips and cuts off power to entire water heater when it detects temperatures over 150 degrees.
This prevents overheating and eventual explosion of water heater.

The ECO will trip for 4 possible reasons:
1) Bad thermostat. Water temperature inside tank exceeds 150 degrees F because thermostat is sticking in ON position, and thermostat does not turn off element correctly.
2) Loose wire inside or near upper thermostat that causes ECO to sense higher temperature
3) Bad element shorted to ground near center of element, and short does not cause breaker to trip
4) Factory-installed insulation and cover are removed from water heater >>> cooler air causes thermostat to read wrong temperature, and thermostat keeps heating water inside tank

Steps you can take:
First thing is to check if factory-insulation-and-cover are present.
Next look for signs of burning at or near screw terminals. Tighten loose wire if found.
Especially check the lower element screw terminals.
Take a photograph of the parts so you can see the parts larger on your computer, and compare parts more easily when buying new parts.
Next most likely suspect are the thermostats.
For around $22, you can buy generic upper-and-lower thermostats at Lowes or hardware store > then replace the thermostat(s) and see if problem persists.
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

If problem continues after steps above
You will need to test water heater parts to track down the exact problem:
You need a inexpensive multimeter from Radio Shack, and the steps are simple, and you will know everything about an electric water heater afterward.
http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html

Answer back if you encounter something not covered above, and I will help.

'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

The heater will only fire if it has water in it. If you just got the house, make sure the gas/electric to the heater is on. Turn off the pump and turn it back on.. See if that works. good luck