Elec. Water heater: Temp. drop problem

My electric water heater (2 months old) has a problem:
When taking a shower, I set the proper water tmep at the faucets. About 5-10 mins into the shower, the water temp drops noticeably. I can readjust the faucets and all is well for the remainder of the shower.
Testing water temps, this problem is consistent. There is a 10 degree difference in water temps.
This heater has both an adjustable upper and lower thermostat. This problem seems to happen at ANY thermostat setting. I can keep the top at the "hot water" setting, and the bottom at the "A" (one level higher setting), or keep both the exact same.
It always seems the top is hotter, regardless of what the bottom is set at.
I do know for sure the bottom heating element does work. For a 50 gallon tank, we don't run out of hot water. It just seems the top one "overrules" the bottom a bit too hastily.
Life was better with the old heater where you couldn't set the top 'stat.
We do have sufficient hot water. This is more of an irritant to me than anything.
I did do the "conversion" on the lower element to give it a higher wattage. I just yanked the bussbar to bring it back to 3800 watts to see if this will make any difference, and correct trhe problem.
Any advice, or do I just have to live with it?
Thanks!
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Electric Water Heaters are slow recovery units. Unlike natural gas water heaters. It is typical to experience a drop in water temperature when youre showering after 5-10 minutes. As your electric water heater gets older and sediment starts to accumulate in the bottom of the tank (thereby decreasing its water holding capacity...), the problem will become worse . A 10 minute shower with an average 40/50 gallon electric water heater is about all you can expect to get . You can make the situation better if you put two electric water heaters in series with one another...but expect to pay bigtime in electricity.
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If you put the two heater elements 'in-series', even if they are now both on at once you will get only half the wattage! So that will just take longer?
You may perhaps be referring to the fact that many electric water heaters have an upper thermostat that, after the upper element has heated the top section of the tank it 'flips over' and then allows the lower thermostat and heater to heat the bottom of the tank. It is often possible, by moving one wire, to bypass the 'flip flop' and allow both the upper heater under control of its thermostat and the lower heater under control of the lower thermostat to work independently. In other words both upper and lower can be on at once/same time thus speeding heat recovery if/when the whole tank is cool/cold. Naturally this means that at certain times this method will increase the amount of current required; if the upper and lower heaters are the same wattage the amount of current will double.
One 3000 watt heater at a time requires 13 amps; double that if both upper and lower can come on at same time. So it becomes a matter of whether the wiring and the circuit breaker are the correct size to supply 26 amps. But overall can't see why it would increase the amount of electricity required! The amount used is a function of how much water has to be heated to the required temperature! Not how quickly it is done!
Final comment; it would not normally be desirable to have both heaters switched on/off by the one thermostat at double the normal current!
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No, he means in series, but he's talking about the water lines, not the electrical ones. If you pipe the output from one water-heater into a second one, and thence to the shower, you get two advantages, first, your starting supply of water is twice as big, and second, whatever water you draw through the system passes over twice as many heating elements, which almost doubles the heat-rise.
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This is Turtle.
I have a cure for it all. Get Natural Gas to you tankless hot water tank system and get a Rinnal Continuum Model gas tankless hot water system and just set the exact temperature of the water you want with a digital read out thermostat and use all hot water. The water will stay the temperature you set it on for days and weeks or even a shower that takes a year. You will have none stop hot water and exactly the temperature you want it to be and will supply 8 gallons a minute. The burners will range between 15,000 btus to 200,000 btus as need be. Bad part $900.00+ for the equipment.
You know adjusting the temperature could do it. Set the temp. of the bottom 5 degrees hotter than the top.
TURTLE
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John L. Wilkerson Jr. wrote:

Are you handy with a soldering torch? or if not do you have a buddy who is? And if not again, are you willing to pay a plumber to solve your problem?
Your problem can be easily solved and you'll have "more" hot water if you just install a "thermostatic tempering valve" at the water heater's location.(Watts makes good ones.) and then set the thermostats on your water heater to keep the water at about 155 F. Adjust the tempering valve to deliver 120 F water and that's what you'll have flowing in your hot water pipes until you run the heater tank down below that temperature. See:
<http://wattsreg.com/scripts/baserun2/baserun.exe?_cfg=./db/wattsreg-products.cfg&_sn=wattsreg-products&_fil=alltrim (cat)%3d'Tempering_Valves'.and.alltrim(family)%3d'Tempering_Valves'&_tar=_view3>
Happy Holidays,
Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)
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John L. Wilkerson Jr. wrote:

Huh? you have two thermostats, set the upper one to a few degrees lower than the bottom thermostat. "Hot water" and "A" setting. My electric thermostat was set in degrees. In any case set the bottom higher than the top. 50 gallon tank shouldn't change much for a 20 or 30 minute shower, my old electric sure didn't. The new Gas is a PITA, way too much difference in temp between thermostat on and off. Electric was less than 5 degrees.
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Have'em se that way now. Top on "hot" and bottom on "a" After 5 or so mins the temp drop is still there.
It also seems the upper element is operating. As a matter of fact I hear a sound coming from the area of BOTH heating elements at times.
I wonder now if I wired that sucker wrong. I have a 2 wire supply, but 3 wires on the heater. I did hook the 2 wires together as indicated in the diagram. The only thing that confuses me is that they have an "L1" and "L2" listed... not a black or white wire.... I have no clue what either is so I simply hooked up the black wire on the supply to the black wire on the heater, plus whatever extra wire color was called for.
at any rate I am still stumped.
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