Hot water heater doesnt seem to work well

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Mar 10, 2013
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My hot water heater is older. Its a 40 gallon. I recently noticed it doesnt seem to stay hot for as long as it used too. I can recall taking 40+ minute showers. Now im down to 20-25min before it starts to get cold. I checked the heater elements and both ohmed out right at 13. Everything looks fine on it. I know the answer is probably to just replace it but im curious why if its functioning properly i wouldnt get heat for longer?
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Joe, you need to be Green.

A Rheem 40 gallon Performance Platinum 40 Gal 10-Year Hybrid High Efficiency Smart Tank Electric Water Heater
has an energy label of using $119 a year in electricity.

.
 
My hot water heater is older. Its a 40 gallon. I recently noticed it doesnt seem to stay hot for as long as it used too. I can recall taking 40+ minute showers. Now im down to 20-25min before it starts to get cold. I checked the heater elements and both ohmed out right at 13. Everything looks fine on it. I know the answer is probably to just replace it but im curious why if its functioning properly i wouldnt get heat for longer? View attachment 142616
When was the last time you drained it of sediment?
 
Hook up a hose to the drain, turn the power off, open the drain and you might be surprised how much crud comes out. Might take several rounds of that.
 
Water heaters require periodic maintenance, electric more than gas. How is the anode rod? How much sediment is in it? Does it make noises?
Makes no noise that I have ever heard. Nothing has ever been done to the unit as far as maintenance.
 
Joe, you need to be Green.

A Rheem 40 gallon Performance Platinum 40 Gal 10-Year Hybrid High Efficiency Smart Tank Electric Water Heater
has an energy label of using $119 a year in electricity.

.
I wouldn't recommend a Rheem water heater to someone unless I really hated them.
 
Looked up the manual. It states if you have hard water the heater elements can get a buildup and need replacement even if the heater element works. Ill probably flush the tank and replace the heater elements and see how that goes.
 
In my experience, this is how they perform when the bottom gets full of sediment. My dad had to replace ours twice during the 15 years we lived in Wyoming, as the water out there was little more than dissolved rock. Not sure how much good it does to drain them, but you can give it a shot and see what comes out. Once that stuff gets burned on, it doesn't tend to let go easily.
 
In the usual design with the inlet and outlet both on the top of the tank, there is a tube inside that makes the incoming cold water flow down to the bottom. If that tube breaks, cold water will mix with the hot water as it is being used, and the outlet will get cold much sooner.
 
Check the thermostats. You may only be heating water in the top half of the tank. When the tank is full of cold water, the upper thermostat will take priority and heat up the top portion of the water to the setting of the thermostat. Once that temperature has been reached, the upper thermostat will then flip power down to the lower thermostat. The lower thermostat switch will close and heat up the bottom portion of the tank until the water is heated to the setting of that thermostat. At this point the tank will be full of hot water. The upper thermostat needs to send power to the lower thermostat and the lower thermostat needs to send power to the lower heating element. If the thermostats don't do their job, the lower element won't heat. And only the water in the top half will be hot.
 
40 minutes of shower time seems like a bit longer than I’d expect to get out of a 40 gallon electric water heater… I would’ve thought 20-25 minutes would be around what you’d get.

The first hour rating gets at this concept, but if you have a 2.5 GPM shower head that’d be 100 gallons of water required for a 40 minute shower. It wouldn’t be too surprising that a 40 gallon electric heater couldn’t keep up with that kind of demand, considering that electric units’ recovery is traditionally lower than gas units’. A quick google says that electric units have first hour ratings around 50-55 gallons.

Of course, this is a simplification (I.E, you’re probably mixing in some cold water at the tap, so you’d be using less than 2.5 gallons of hot water per minute), but I think that the scenario is a pretty big ask from the heater. Setting the temp higher would increase capacity in theory, as you’d need to mix less hot water in per minute to get the same output temp from the faucet, but there are scald risks associated with higher settings.

What GPM rating does your shower head have? And how cold is the water entering the water heater? (Our 40 gallon gas water heater performs much better when the incoming water isn’t as cold as it is in winter in MN, which bottoms out around 40 degrees or so.)
 
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