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We have a large tank conventional water heater. Electric, two elements. We get hot water from it. It's 113F at the kitchen faucet and we can take showers/etc. It does take quite awhile for the initial hot water to arrive, though (I don't know what normal is in this house, though). The heater is only 2 years old.

I went to flush sediment from the drain at the bottom and the water in my bowl is cold. Like - room temperature. Nowhere near 120. This is after hours of non-use. So it seems that only the top element must be doing the heating - right?

I removed the upper and lower panels and checked the thermostats. Seemed fine but increased both slightly (faucet temp now 124). I get a voltage on the lower panel with the power on.

With the power off, I did a continuity test on the lower heating element and I get a tone so it seems fine. (Is it definitely fine? Is there more to test?)

What else could be wrong? Faulty thermostat or controller for the lower element?

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    A few years ago, scientists discovered tank water heaters kept at 120F are breeding grounds for bacteria. Sickenings happen all the time - they just aren't correllated because they are usually isolated/random incidents. This was discovered because the water changes in Flint, Michigan caused a cluster of them at the same place and time. Now that it's understood, health experts are recommending 140F in the tank, and thermostatic control valve(s) to prevent scalding at the tap. A side effect will be more useful hot water, since less hot will be used with more cold. Jan 21, 2023 at 9:29

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Cold water is piped to the bottom of hot water tanks and pushes hot water out at the top.

Whenever water leaves the tank, cold water enters at the bottom.

Depending if the cold pipe is close to the drain is why you get cold/cooler water.

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  • So are you saying nothing is wrong with the heater? Also how could the water in the bottom be like 60 degrees colder than the target temperature even if we haven’t been home for 3 hours? Jan 21, 2023 at 3:39
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    Do you get hot water? Does it last? If so, it's working. Heat rises into thermal layers....unless you mix it. Quit futzing with it before you break something. Jan 21, 2023 at 5:51
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    @GregSmalter, I don't think the answer is stating that "nothing is wrong with the heater", it is stating a fact: when the drain port is opened with the cold supply also open, cold supply water immediately flows to the bottom of the heater via the inlet dip tube. This could easily explain a significant temperature difference. Jan 21, 2023 at 16:04
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To add to the answer by crip659, if the final temperature is as desired then it is not the hot water cylinder. It has minimal say in the water flow. The things affecting the flow/lag are

  • Water Pressure
  • Diameter of the delivery pipe
  • Distance from the tank.
  • Temperature of water in the cylinder.

Buzzing the elements is not enough, you need to measure their impedance (resistance).

For a 3KW element the resistance would be about 16 ohms at 220V or 4 ohms at 110V

Adding for completeness. It is normal for the hot water to be on the top, which is why you take off hot water from the top. And by default, at least the bottom third of the tank would be cold.

  • To increase the amount of hot water in the tank, you can lower the thermostat. For a two-element/thermostat, the outcome is more complex to predict. I suspect it will turn off the top thermostat earlier and lower the water temperature.
  • To increase the temperature of the hot water, you can increase the thermostat setting. This would also increase the amount of hot water in the tank, slightly. Caution - I have been told by plumbers that increasing the temperature too much can cause an early failure of the tank. There may be a spec on the tank - I am not sure as I have had custom tanks built for myself for the last 25 years.
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  • I tested the resistance and got 12.5 ohms. I also lowered the bottom thermostat closer to its original position and the tested the sink 4 hours later and the temperature was lower, proving the lower element is doing something. Jan 26, 2023 at 18:52
  • I am not sure of the dynamics of 2 elements and 2 thermostats, it would be a lot more complicated. For a single one, lowering the thermostat would increase the amount of hot water in the tank. It will not raise its temperature. Jan 26, 2023 at 20:52

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