"Is it a thermostat problem?" Well, yes and no. OK? `

I mean, if the heater heats to temp, the thermostat is working, to a degree. But there are several factors. IÂm guessing you are talking about an electric heater? If so, they work with two elements, independently controlled. What type is it?

But your heater is probably under warrantee. You should go to the manufacturer for that.

Pinoke

I am having the same problem but I have a gas unit. It is a A.O.Smith Promax mode FCGL 40 248 40 gal and is about 6 years old. It works great all the time exept for the first shower in the morning (around 5 or 6 AM) maybe twice a week. Any ideas?

We have an A.O. Smith that's about 3-4 years old and we have a similar problem. Sometimes the water is hot, sometimes it's warm or lukewarm. After it's been used a while, it generally heats up. I questioned this when the heater was new and was told it's because of the safety features that all new water heaters are mandated to have.

Hmm, never heard of any kind of safety feature where a tank lets you get hot water on some days or at a certain times of the day, but not other days or other times. Unless you have some kind of a system with a timer, the tank doesn't know what time it is or what day of the week it is. It's supposed to try to keep the water at the temperature that you set it for. If it's not doing that, I think there is a problem. With a gas heater it's either a thermosthat or a quirky gas valve.

It's funny, but I have an AO Smith that's about 4 or 5 years old. It doesn't work like yours. It gives hot water whenever the hot faucet is turned on.

If it's electric, some places in the country have remote disconnects where the power company can shut the electric tanks off when the power demand for the area is too high.

We have a 3-year-old big-box brand 40-gal gas water heater that behaves the same way. Seems like our prior house had the same issue as well. The water has not been cool to the point of being tepid, but it is noticiably cooler when the hot water hasn't been used for several hours.

Our shower has one of those Delta valves where the mix is pre-set, and it usually stays put. But if we shower in the evening, we turn the temp down to a comfortable level, then back up to a comfortable level in the morning.

My theory has been that the thermostat must be near the top of the tank where the water stays warmest when just sitting idle in the tank overnight. Then, running the water in the morning churns it up and causes the burner to reheat the entire tank. Just a theory, but it sounds like a common problem.

makes you wonder it the cold water inlet is close to the hot water exit inside the tank. the fresh cold water coming in goes straight out the hot side.