Yes even the Faucetman can be wrong. Just ask my ex-wife. As much as it may be hard for you to believe even I am capable of making a mistake, I divorced my first one (and never made that one again) and then there was the following discussion dialog from this weekend on GardenWeb, one of my favorite forums:
“The hot water heater is 3 yrs old. It is making dangerous scalding hot water which automatically shuts it down. Hubby goes into basement and hits the reset and it starts up again. He adjusts the temperature to less hot. I run out of hot water in the shower everyday so he adjusts the temp back to where it was for the past 3 yrs and so it starts making scalding hot water again. Then it shuts down and he has to go press the reset button again. Cyclical problem. What the heck! Can somebody help us, I'm trying to avoid calling the plumber if we can figure this out.”
Probably not the answer you want to hear but basically it sounds like you need a larger capacity HWH. You are flirting with danger in allowing the heater to overheat so much that the reset is popping. One day instead of the reset working you will build up enough pressure to blow the Temperature/Pressure relief valve and then you will be in for a major fix if not worse depending on where the TPR is drained to and possibly ruin the HWH. It maybe a good time to look into the newer instant hot tankless HWH. They can be expensive on installation but long term savings on not having to keep water heated constantly usually results in a payoutand will give you all the hot water you need on demand.
The Correct Answer (I stand corrected)
I'm not sure I completely agree with faucetman... some additional information would be helpful. how big is the water heater? 40 gal, 50 gal, larger? Under what conditions does it run out of hot water? Is it when only one of you take a shower? Is it when two of you shower after each other, etc? Is it when you do laundry or some other large demand? I suspect that something else is going on - I suspect that the bottom element is burned out and shorted out - or possibly the thermostat is malfunctioning. My first guess would be the lower element. You do need to fix this problem now. The reset button is a safety device - it works when the normal operational controls fail. It is a second-line defense against catastrophic tank failure. You don't want to count on that to continue to prevent serious damage... it's kinda like the emergency brake in your car...you don't want to drive the car knowing that the regular brakes don't work and count on the emergency brake to stop you. As FaucetMan pointed out, you do have one more layer of protection, the TPR valve- that can cause flood/steam damage if it releases but at least it won't level your house like an exploding water heater can. As I said, I think you will find that the lower element is burned out - but you need to get it fixed now and stop resetting it.
The link below shows what happens when a water heater lets go. It doesn't happen often because of the safety devices, but it's a good reminder of why there are a couple of safety devices on the heater and that we shouldn't ignore a failed operating control.
Hubby checked the capacity of the WH. It is 64 gallons. We are only 2 people here.
Yes it is only recent that the scalding water started happening. He lowered the temp & now we run out of hot water on ONE shower. So he set it back where it was and we got the reset problem every few days. I do not take long showers.
My Mea Culpa
I absolutely stand corrected and agree with the previous answer. A 64 gallon HWH should be sufficient for a 4 person family not just a 2 person family. Obviously the tank is malfunctioning and needs repair and soon. I do still believe that a tankless might be more satisfying and efficient but far more expensive than just repairing the existing unit.
The bottom line, as I have said in so many blogs before, DON’T SCREW AROUND WITH YOUR HOT WATER HEATER! Today’s modern product is manufactured for safety and reasonable efficient service if something malfunctions there is a reason and not something to wait around or more importantly fool around to try to avoid the inevitable. I am constantly reminded of the early Saturday morning thread I answered about a hot water heater forcing hot water into all of the cold water lines including the toilet. Someone had replaced the TPR valve with a plug and the HWH was just before exploding. Thankfully I was up early that morning reading my forums and told the poor guy to turn the darn thing off and call a plumber just before his HWH was going to become a guided missile through the roof or worse through the livingroom, bedroom and out through the garage to the neighbors house.