Welcome to Just Answer.
Sorry to hear about your problem.
Typically, if you have hot water then the elements are working fine. If you do not have any hot water, then it may be the upper element that is defective or the upper thermostat. If you are running out of hot water quickly, then it may be the lower element that is defective or the lower thermostat or the dip tube.
You can test the elements to see if they are defective (even if they are new), with an Ohm-meter. You will get a reading of about 100 ohms or higher across a good element. If the needle on the meter doesn't move, then you have a bad element. If the element checks out good, then replace the thermostat. You can also measure the resistance from the element connections to the tank; they should be open and any reading indicates a bad element that is shorted to ground.In addition, keep this in mind-- thermostats fail more often then the heating elements. Anytime there is a problem, the thermostats should be checked first. It's also not a bad idea to change the thermostats (even if they test good,) if you are changing the elements.
In every water heater, there is a plastic dip tube that brings cold water to the bottom of the tank to be heated and prevents it from mixing with the already heated water at the top of the tank. If the tube splits or breaks, then cold mixes with hot and suddenly your water heater doesn't work like it used to. You have the option to replace this part which can restore your tank's function and save you the cost of a new heater or you can simply replace the water heater; which ever makes more sense, depending on the condition of the rest of the water heater.
Click here to learn more of how the dip tube works and how to replace it.
If you need further help or clarification on this answer, please do not hesitate to reply to this post.
Thanks for asking your question at Just Answer.
Best of Luck, Brian
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I used an ohm-meter and I get electricity to the themostat and to the elements I just replaced. Also, the reset button isn't working. But I replaced the top thermostat with a new one. And still no hot water. Does this mean I need to replace the water heater?
If you have replaced both thermostats and both elements and verified that the dip tube is intact, and verified that the water supply is getting to the heater, then it may be a bigger problem. Water heaters typically last around 10 years; if you are at that point then you may want to think about replacing it, especially if you see any rust anywhere on the unit.
I forgot to mention:
Verify that the hot water heater has been flushed recently. It needs to be flushed regularly, to prevent sediment and build-up from forming, which will eventually make it's way into the plumbing lines. These small particles can block the small openings in a faucet cartridge/ aerator and also prevent the making of hot water.
Click here for more information on how to flush a hot water heater.
I haven't checked the dip tube. Would that keep it from the water getting hot? I don't even get warm water. I haven't replaced the lower thermostat. I replaced the upper thermostat and the reset button won't work. I was told that even if one thermostat wasn't working then I would still get some hot water? Could I have bought a defective thermostat. My water heater is a 2003. If my water heater needed to be replaced I wouldn't get any electric from the element or thermostat, riight?
Generally the a defective dip tube will still give you some hot water, just briefly. A bad upper thermostat or bad upper element would make no hot water. I would test the upper element and verify that the upper thermostat was installed correctly. There is a chance that the new thermostat is not working correctly and you may want to try bypassing it temporarily to see if you get any hot water. If you are reading electricity at these areas, it should be working. The heater is not that old so I don't think you need to replace it. I would verify that the sediment has been flushed out.
I wouldn't bother bypassing now that I think about it.
I forgot to address the reset button (high limit switch)...this very well could be the problem.
The top thermostat usually has a high limit switch that will trip if the water gets too hot. When it trips it shuts off the electricity to both the upper and lower heating elements.
To reset the high limit switch there is usually a red button that you must press. When the upper limit switch trips it is often an indication that something else has gone wrong with the heater. The reset button trips because the water heater got too hot. The only reason that a water heater will get too hot is because one of the thermostats got stuck. Since the bottom thermostat is the only thing you haven't replaced, I would guess that this is the problem and I would replace it. If after you replace the lower thermostat and it still doe not reset then the reset button is defective and that would need to be replaced. That should fix it.