Probably either the bottom element is not heating or the water usage is excessive. But if the heater is set at 110 deg, that could be the problem. I have mine set higher so that the usage for bathing includes a goodly amount of cold water. Think in terms of storing heat rather than gallons of water. The higher the temp, the more heat is stored. I would do more tests to verfy the actual operation of the bottom element.

Well, before replacing the elements and thermostats, I checked both of the elements, and they both checked out as being good. Even so, I replaced them with 2 new ones (bottom and top) and those test good too. I don't know what else I could do to ensure it is actually working. I have both thermostats (just replaced) set at roughly 135. The water is hotter than it was before, but no noticeable difference in the length of time the hot water lasts. As far as excessive usage, I can't see that. I take maybe a 15 min shower, and by the time I am done, the water is all the way on hot and it is only warm. That is without having run the dishwasher, clothes washer, or anything else that consumes hot water that day...outside of the occasional hand washing or something.

All tank water heaters send cold water to the bottom of the tank via a dip tube and pull the hot water off of the top.

The way electric water heaters work is that the top element comes on to heat a small amount of water at the top so that there is quick hot water. Once the water in the top of the tank is warm, the lower element comes on and the upper element shuts off. The lower element heats the rest of the water and it takes much longer (since there is much more water to heat)

Given the way these heaters work, I suspect that your lower element isnÂt working. You are getting the hot water off of the top but the lower element hasnÂt heated the rest of the tank.

The test would be to check the power to the lower element with a volt meter  or more conclusively test it with an ammeter to see if current is flowing through the element.

If you donÂt have a meter, a more informal test would be to wait, say thirty minutes, for the water heater to come up to a normal temperature after using any hot water. Then shut off the power to it (be sure to do this!). Then turn off cold water supply to the heater and open the drain. What you would be looking for is the temp of the water at the bottom half of the tank. If the first 25 gallons is not very hot, your lower element is not coming on.

And,...a 15 minute shower is a pretty long shower. If you don't have a "low flow' shower head it would take about an 60-80 gallon tank to supply what you need.
If the bottom coil and thermosthat seems to check out okay, check to be sure that the bottom thermosthat is installed tightly against the tank. I had one recently where the thermosthat was okay but wasn't tight. There is a bi-metal switch in there that has to sense the temp. of the tank.

To add a further explanation to my earlier response and the responses of others, the typical water heater uses an interlocked upper thermostat. It sends power to the upper ELEMENT if the temperature is lower than the setting of the thermostat. When the temperature rises enough to exceed the setting of the upper thermostat, it switches off the upper ELEMENT and sends power to the lower THERMOSTAT. The lower THERMOSTAT sends power to the lower ELEMENT until the lower thermostat is "satisfied". The element must actually receive power in order to heat-see my original post. A thermostat that contacts the water tank loosely would result in hotter water, not cooler.

Well, as I said, I've tested both of the elements that were in there, and both of the new ones that I replaced (even though the old ones tested good). Yes, I have a meter, and tested them on Ohms. This is our 3rd house with a 50 gallon electric water heater, and we have never had water run out this quickly before. We have always taken about the same length of showers and have never run out as quickly as we are now. It sure seems that something has changed, and I'm not thinking it is the elements or thermostats since they've all been replaced now and I'm seeing the exact same results as with what was in there (which didn't test bad either). Is there anything else that could account for the lack of hot water?

You may have a broken dip tube which is allowing cold water to enter at the top of the tank instead of the bottom.

Hi lcottrell,

I did notice earlier that you had tested the elements and had replaced both the elements and the thermostat. But you need to really verify, at least, that there is voltage to the elements when there should be and ideally that there is current flowing through the element circuit. A successful current test would rule out a lot of electrical issues. An ohm test on the element only tells you that the element is good-- it doesn't tell you if it is getting power.

Unless I am forgetting something, there is either an electrical problem, a mechanical problem with the thermostat, or you are using all of the hot water in the tank (which would include a low setting on the thermostat or diminished tank capacity due to lime buildup). If you had serious lime buildup you would have known it when you pulled the bottom element.

Less likely but still possible is a tank that has been connected to water supply incorrectly (the cold is connected to the "H" outlet on the top of the tank) or the dip tube is damaged or missing causing cold water to mix with the hot in the tank. Of those two, the improperly connected plumbing doesn't fit your symptoms, but the damaged dip tube does.

Since the electrical is the most likely problem, you need to conclusively rule that out before you do anything else. I am sorry if it sounds like I am telling you to recheck something that you have done already-- but if you are stuck, then you need to perform some conclusive tests.

Ok, that's something I haven't done. I'll test them to make sure voltage is working properly too. I did think about the dip tube, and went to Lowe's to see about replacing it. They had no idea what a dip tube was. I had to bring my water heater manual in with me and they had several guys look at it, and all had never heard of that before and said they don't have them.

Certain water heaters manufactured by major water heater manufacturers between August 1993 and March 1997 contained potentially defective dip tubes that were manufactured by Perfection Corporation of Madison, Ohio. You're guessing your water heater is newer than that, but check the label on the water heater -- it may have been manufactured several years before it was installed.

Here's information about the settlement:

http://stateind.custhelp.com/cgi-bin/stateind.cfg/php/enduser/std_adp.php?p_faqid=260&p_created=1053005959&p_sid=S3DBC*ti&p_accessibility=0amp;p_lva=&p_sp=cF9zcmNoPSZwX3NvcnRfYnk9JnBfZ3JpZHNvcnQ9JnBfcm93X2NudD03NSZwX3Byb2RzPSZwX2NhdHM9JnBfcHY9JnBfY3Y9JnBfc2VhcmNoX3R5cGU9YW5zd2Vycy5zZWFyY2hfbmwmcF9wYWdlPTE*&p_li=&p_topview=1

Here is an article with instructions for testing if your dip tube has a problem:

http://stateind.custhelp.com/cgi-bin/stateind.cfg/php/enduser/std_adp.php?p_faqid=261&p_created=1053007758&p_sid=S3DBC*ti&p_accessibility=0amp;p_lva=&p_sp=cF9zcmNoPSZwX3NvcnRfYnk9JnBfZ3JpZHNvcnQ9JnBfcm93X2NudD03NSZwX3Byb2RzPSZwX2NhdHM9JnBfcHY9JnBfY3Y9JnBfc2VhcmNoX3R5cGU9YW5zd2Vycy5zZWFyY2hfbmwmcF9wYWdlPTE*&p_li=&p_topview=1

Here is a link that might be useful: dip tube test instructions

Wow! This is the exact same problem I have been having. I have a 60 gallon tank (more than enough), I have the thermostats set up to 140, I replaced both of them and the heating elements, even though I tested them to verify they have voltage and there was no resistance. However, I can't take a 15 minute shower after no hot water has been used for 24 hours without having to continually turn up the hot water until it's all the way on, and still getting colder. I moved into the house 2 years ago, and I never had a problem with having enough hot water, but over the course of a few days, suddenly it runs out really quick.

So far everyone has been telling me, "It has to be the electrical system, replace the bottom element", but I'm convinced I'm testing everything correctly and the problem isn't going away.

I think my tank was manufactured in the mid 1990's, I'm going to check back at home tonight to verify and check the serial codes then report back here.

I hope you have better luck than I did. I spent a while on the phone with the Rheem technical support folks, and that was worthless. They had me retest everything I'd already done, which was the electrical as someone here suggested and the ohms resistance on the elements. Everything was good. Then I tried the dip tube test that someone else here suggested. The thermostats are set to roughly 135. After running hot water from the tap for 10 minutes, I then took a sample of water from the drain line and it was 109 degrees. I waited an hour and took another sample and it too was 109 degrees. Rheem said they think my dip tube may be bad but that is one of 2 parts not covered under the warranty. Go figure. The tank was manufactured in 1999. With already replacing so much on it and since it has about 7 years of use now, I'm going to just replace it with a new one. Of course, I'm taking my elements and thermostats that I just put on and saving them for when the next one starts acting up.

Sorry to hear about it. At some point you have to lick your wounds and move on.

Yeah, I hope I have better luck than that. I checked the serial number, and it was in the list of tanks that the lawsuit mentioned. It's too late for me with the lawsuit, but the tank itself is still good, no leaks or other problems. I tried the test mentioned, and the water came out real hot on the bottom. It's enough evidence for me. I'm going to try and find another dip tube and try to fix it myself. I am not too optimistic about finding one though.

If the budget is really a problem and finding a new dip tube is too difficult, converting the drain fitting location for the new supply inlet will work. Remove the existing drain valve and run the cold supply to that point. Heaters were often built that way prior to the 1960's.

I just wanted to post back my final results for anyone else having the problem.

The plumbing was done in a way that I could not remove the cold or hot connections from the tank without cutting the cpvc lines, so I broke down and did that, replacing them with flex lines so I can remove them in the future. Well, low and behold, there was no dip tube in the tank at all. There was a dip tube gasket, but no dip tube...not even remnants of one, so I'm sure it was removed at some point for some reason. I called the manufacturer since it is still under warranty and they sent me a new dip tube and gasket out overnight. I put it in and last night, my wife and I were both able to take normal length showers and we did not run out of hot water.

I'd like to thank everyone for their ideas and input.

The absence of the dip tube means that after just a few minutes of not using the hot water, the hot water supply returns for "one more shower". This "recovery" is much faster than if the heater is starting from cold. The cold water previously introduced slowly "sinks" to the bottom of the heater and/or is warmed by the surrounding water previously heated. In retrospect, we should have discussed this earlier. I am glad the mystery is solved.