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Dave M
Water heater issues

My electric water heater does not seem to be putting out as hot of water as it should. In an effort to get hotter water I've increased the thermostat temp to ~130F. My showers still seem luke warm and at the tap I'm getting about 105-110F. I understand they'll be some line loss but I shouldn't be getting luke warm showers when my thermostat is at 130. There may be issues with my mixing valve in my shower, but in my investigation I opened the drain on the water heater to test the temp directly from it. The water was essentially room temperature and that makes me think my lower heating element or thermostat has failed. How can I go about confirming which one (thermostat or heating element) have failed, if any?

Dave M

Re: Water heater issues

You will need a multimeter.

First, test your meter to be sure it's working properly. Set your meter to the AC volts setting, stick the probes into a working electrical outlet, and verify that you get a reading of about 120V. (Anywhere from 110V to 125V is OK; this is the expected voltage range for a standard outlet in North America.) Remove the probes from the outlet. Second test, set the meter to Ohms (or resistance). Touch the probes together; it should read 0 ohms. (For an analog meter, the needle will swing all the way to zero on the right. If it doesn't, tweak the ohms adjust knob. If it still doesn't, replace the battery.)

You should always test your meter against known conditions before using it to test unknown conditions. A faulty meter can lead you to incorrectly believe a live wire is dead. Then you could be dead, too.

Now test the water heater.

First, shut off the power to the water heater. After removing the covers, use the meter on the AC Volts setting to make sure the power is indeed shut off. Probe between each incoming wire and ground (the tank) -- it should be zero volts. Also probe between both incoming wires -- still should be zero volts.

Now that you've established safe working conditions, you can test the elements. Disconnect the leads to the elements and use the "ohms" setting on the meter to measure across the terminals of the element. It should read near zero ohms. If the needle doesn't move or it reads infinite ohms, the element is bad.

By the way, the lower element is most likely to fail as it gets the most use. Water heaters primarily use the lower element. If enough water is drawn off, it will switch on the upper element and off the lower.

If both elements are good, you may have a bad thermostat. The lower thermostat is pretty easy to check: meter across the terminals and if it reads zero ohms when the tank is cool, it's probably working. It would read infinite ohms if the water was hot.

The upper thermostat is more complicated, because it must switch between the upper and lower elements. Off the top of my head I can't remember the exact procedure to test the upper thermostat.

Dave M
Re: Water heater issues

Thanks for that write-up. I'll put it to use and may have more questions depending on what I find.

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