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adamczar t1_jcukfb7 wrote

Idk 2-3 showers seems about right.

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JohnProof t1_jcun08k wrote

>It lasts maybe 2 or 3 showers then runs out.

That honestly sounds about right. A lot of shower heads are about 2 GPM, so if you have a 40 gallon heater that's only gonna be 20 minutes to completely empty the tank.

But it's worth doing routine maintenance to see if there's anything that needs fixing: Flush the tank, visually inspect the elements, test them for continuity, pull the anode and while it's out check the dip-tube, and test that the lower thermostat is working. All of those could contribute to colder showers.

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scouter t1_jcuqy71 wrote

Right so far, but consider a thought experiment. After the first 20 gal of hot water has been drawn, the “bottom half” will be full of cold that the water heater is heating. But we know that there will be mixing, thus the hot water coming out after 10 minutes will be colder than the first gallon. Notably colder, because the tank is pulling in 50-60 degree water (typical in North America). And this will continue, so the “40 gal” capacity will be felt in the shower as exhausted well before 40 gallons of use.

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BIT-NETRaptor t1_jcv2di5 wrote

Do you in fact know that there will be mixing, or did you guess? I thought so too until I watched a Technology Connections video on electric water heaters.

https://i.imgur.com/hoqaigM.png

It mixes much less than you think.

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scouter t1_jcv5eex wrote

True, I was guessing, but I have always had a gas water heater. The stratification should not come as a surprise as I am familiar with sharp thermoclines in the ocean but I did not make the connection.

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JohnProof t1_jcuvt4f wrote

That's where the 2 thermostats and dip tube come into play:

If the dip tube is working, it's putting the cold water into the bottom of the tank which helps stratify hot water at the top where it gets drawn off. And the lower thermostat will kick on to heat that cold makeup water to help maintain the tank temperature.

Once too much hot water is used and the lower element can't keep up, then it shuts off and the upper element kicks on to re-heat water near the draw-off as quickly as possible.

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Leftygolfer814 t1_jcuhyig wrote

If the tank is electric you might need to change the element and thermostat. If gas the only thing you can try is draining all of the water and sediment for better heat exchange.

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PeterGoddard t1_jcul1ki wrote

You might need a new dip tube. It's a pretty cheap repair.

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wucrew t1_jcurgeq wrote

This is the answer, cold water coming in is going right out to hot side since dip tube is cracked.

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NotWorthTheTimeX t1_jcuz8ud wrote

It’s possible but all depends on how quickly they shower. I believe the dip tube failed on my 9 year old Brandford White 40 gallon. It would get much colder after 5 minutes in the shower. After a few more minutes it was only warm on full hot. Due to how much rust there was at the cold water tank inlet I chose to replace the tank.

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brnjenkn t1_jcunvt9 wrote

2 - 3 showers sounds about right. You might be able to stretch it out with a low flow/high efficiency shower head. I love mine but the gf needs her wand...

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Biscuits4u2 t1_jcuprxl wrote

Yeah 2-3 showers is about what you can expect from most standard size water heaters. You could try turning up the heat to max so you don't have to use as much hot water.

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DoubleHexDrive t1_jcuvsce wrote

Your initial memory could be during the summer time when it takes less hot water to make a shower. Or fewer teenagers, lol. A cracked tube, dead element, and full of sediment are other things to check.

I upgraded my 50 gal tank wjth a 105 gallon Marathon years ago. Cranked up the temp a bit and installed regulators on the showers to prevent excessively hot water coming out. Even with a family of six, we never run out of water.

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bassjam1 t1_jcuio4x wrote

Are the showers getting longer? My old water heater did fine until my eldest daughter became a teenager and her showers tripled in time duration. With 3 daughters (and one son) I upgraded from a 40 gal to an 80 gal to future proof the house.

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Pomegranate4444 OP t1_jcuka4w wrote

I do have teens. This is definitely part of it but still seems to run out too quickly

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LindsayOG t1_jcurwt2 wrote

2-3 showers would be about right on an average 50 gallon tank.

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Mysterious-Salad9609 t1_jcuvuh9 wrote

Have you drained the tank? My 50gal tank was out of hot water in about 20m due to excessive buildup of sediment in the tank. Upgraded to 80gal hybrid and I can take an hour long shower now without having to turn the handle to compensate for lower water temp.

Kids took a bath in our 50gal jacuzzi tub, then they took a 20m shower, then the wife and I took a shower after and we just started to run out of water after 20mins.

80gar hybrid Rheem. Heating water after running out takes 4hours(we're asleep anyway) and only costs 20-30¢

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RenzoARG t1_jcuwlg6 wrote

If it's electric, you need to replace the resistance that heats up the water. Otherwise, all you need to do is remove the plaque buildup by filling the heater pipes with either vinegar or hydrochloric acid and purging it after an hour or so after it did its chemistry. Repeat with clean water 2 or 3 times to remove any traces of acids (tho it is not dangerous, it does sting in your eyes a bit if you shower with those residues).

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incensenonsense t1_jcv3jr1 wrote

I recommend sticking with vinegar and skipping the hydrochloric unless you have some product specifically diluted for water heaters or are a pro with extensive knowledge on use and safety procedures. The muratic/hydrochloric acid sold for pools is so concentrated that it’s downright dangerous. Need to wear acid gloves, goggles, and be really careful. In an OSHA approved setting pretty sure it would require gown, face shield, and ventilation. Putting in too much would also corrode through the metal inside the water heater very quickly, and if any got in your eyes you could become blind and on skin you would get chemical burns.

Vinegar or citric acid (or even glycolic acid which is in Zepps descaler) are weaker acids and are effective at dissolving minerals but gentle enough on the water heater internals so really good for this application. Still be careful not to get any in your eyes.

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gerrycgc t1_jcv02n1 wrote

Check outlet taps first.

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bigedthebad t1_jcv2eee wrote

Get a tankless water heater and never worry about hot water again.

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imnotsoho t1_jcv3l31 wrote

If you have hard water your tank may be full of buildup. Figure out how to turn off supply and drain the tank so you can measure how much it holds. If it is down from the listed volume it might be time to change it out.

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BaaadWolf t1_jcv4tti wrote

Could also be sediment /rust build up inside the tank but it doesn’t seem old enough. Many tanks have a valve in the base that can be used to dump that water into the floor drain. That might help.

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1

Sethjustseth t1_jcuo54t wrote

I had a problem with my old tank becoming lukewarm after 1.5 showers. I changed our shower head out for a 1.8 GPM and haven't run out of hot water since. I have no idea how many GPM the old one was...

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