Running out of hot water in one shower

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TipsMcStagger

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I recently had my water heater replaced with an AO Smith ENLB-40. My master bath was renovated a few months before the old water heater failed. I can't remember exactly when but around the time the new heater was installed, I installed this larger rain type shower head. The specs for the head indicate it flows 2.5 GPM. Prior to installing this head, I had a smaller Delta Pivotal shower head that was installed during the renovation but it too advertises 2.5 GPM.

The main line to the master bath was plumbed with 3/4" Uponor but I believe it steps down to 1/2" at the consumers (though I'm not sure about that).

The past couple of times I took a lazy shower, I've run out of hot water. I haven't timed it but I'm guessing around 10 minutes. This was first thing in the morning with no other hot water having been consumed.

So that's around 25 gallons of water and obviously, it's not all hot water. In 10+ years with the old water heater, I never once ran out of hot water granted, the majority of that time was not with the renovated bathroom.

Does this sound right? Am I exhausting the capacity of this heater with one shower? Or is it possible the heater is not adjusted or functioning properly?

Thanks.
 
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John Gayewski

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Is your cartridge set all the way hot? A way to check the status of your hot water supply would be to take one of those showers. Then get out of the shower and run hot water to a sink. Measure the temp.
 

WorthFlorida

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Water heaters are set to 120 degrees from the factory. It's the hottest you want it to be. I have found the new WH are so well insulated that the thermostat's ambient air is hotter therefore it senses the water temp more accurately at 120 degrees. Your old WH may have had the temperature set higher to over come heated water shortage and many remove the insulation around the thermostat when adjusting the temp and not replace it.

As John suggest, you can do it before taking a shower to measure the water temp and it should be about 120 degrees. I had one thermostat in a new WH I had to set on the dial to 129 degrees to get 120. Florida water is warm, starts at about 75 degrees.

What is the brand and model of the tub/shower valve if known?
 
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TipsMcStagger

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All of the fixtures in the bathroom are Delta Pivotal.

I did attempt to adjust the cartridge this past summer. There were a few times I'd been exercising in the 90+ degree FL heat and wanted to cool off in a cold shower. But at full cold, the water was not refreshing. I know the ground water is warm in FL, especially in summer, but summer showers had been markedly cooler before the shower was renovated. Adjusting the cartridge helped but I I'm not certain I have it optimally adjusted.

I'll try to find a thermometer to determine the temp of the hot water.
 

breplum

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Tank water heaters only deliver 65% of their capacity before the incoming cold mixes (via the dip tube) and noticeably begins lowering the temp in the upper reaches of the tank (where the hot water rises to).
 

TipsMcStagger

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Yes, but the old water heater was a 30 gallon capacity. This new AO smith is a 40 gallon. In more than a decade with the old heater, I never ran out of hot water. And I'm certain I took some long showers in that time.

I realize the new shower is a variable. I'm just wondering if this shower/showerhead flows so much more than my old shower that even the upsized heater can't keep up?
 

TipsMcStagger

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Hot water from the tap shows about 110 degrees.

I'll try to adjust the thermostat to see if I can get it to 120.
 
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