I have a 6 year old about gas water heater , I believe 50 gallon, I have hard water, had the pressure relief blow out a year an half ago an replaced an told me to set on low setting an if blows again that look another new water heater , wash 3 big loads cloths not to far apart in afternoon, usally water not to hot to take shower an all sudden , it hot, never notice that months , look heater an not hear it fire up like noise makes when burner kicks up to heat an lite for diagnostic code flash normal, no high tempture or thermostat sensor failure, normal operation, the copper hot pipe come out feel hot touch, anyone know these? Maybe got burner kick up with wash 3 loads cloths together an got water real hot? As this unusual to have this hot water since temperature setting is on low, can't figgure out why hot water, unless it cool down tomorrow as insulated tank keep water hot long while an burner kick up with 3 loads cloths washer close together ? If was malfunction, I think diagnostic code would flash to show what wrong but flash once for normal operation

Have you been yearly flushing your water heater? You may be having sediment issues, especially since you have hard water.

We just switched to a tankless water heater last week. It needs flushed every few months.

Keith

Totally flush the tank. fill back up, and flush out again. If you have hard water, and the anode rod has never been replaced; replace the anode rod. Those anode rods should be replaced every three years.

Assuming you were using the washer while you showered I would think you have an old control valve at your shower. Those older control valves are notorious for sudden bursts of hot water when another item is using cold water like a toilet being flushed.

My wife will intentionally use the dishwasher or washing machine BEFORE she takes a shower.
Once the washing machine is DONE she waits about 15 minutes, the water is hotest in the tank then after being heated and refreshed. So yes Dave that is normal

Still hot this morning, I wait till later day , before turn thermostat lower, don't get why so much warmer

Might be a question for the repair man

Here's what happens if it keeps on heating.

https://m.youtube.com/watch?v=jbreKn4PoAc

I would just ignore it. I'm sure it will be fine.

Hottest water from my hot water heater is always after I've run the hot water for some time.
As in doing dishes and rinsing in all hot.

Hippie, that was funny, hope the pressure relief valve doesn’t fail.

Water heaters and pressure tanks can total a home

It had a new pressure relief valve on it a yr an half ago , I can't hear the burner kick up, maybe water still hot from yesterday if really kick up with 3 loads in washer close together

Read your household insurance policy, in fine print buried in page 12 is a clause you have to replace the hot water tank every 6 years. Few people pick up on this hidden gem.

How does sediment cause water to get hotter ? I thought other way , old one lasted 13 yrs an start leak, if turn thermostat down vacation setting, should that take care potentional problem ? It has a red light with codes for any trouble an flash as normal operation , I just hate see blow another valve out when gone, awful mess

Never understood why people call them hot water heaters. If the water was hot you wouldn't need to heat it.

My thoughts exactly. At that point wouldn't it be a water reheater.

Save you some money on gas and switch to tankeless mine paid for it’s self with in a year.

If you flush it get ready to replace the drain as I doubt it will seal especially if you have hard water. Just something I have learned over years of doing that.