Our shower only stays hot for 1.5 showers (about half-a-shower too short!). We have a 50 gallon Kenmore electric hot water heater that is only two years old. We had it fully serviced to try to figure out what might be causing the issue - the upper and lower elements and thermostats are fine, he drained more than half of the tank and the temperature held just fine. There are only two of us in the house, and we are not running the washing machine or the dishwasher at the same time; we are taking our showers one after the other so this isn't a situation where there isn't enough hot water pressure for two showers to run at the same time. I'm going to guess that the Grohe shower fixture is about 20 years old (we just bought the house about 18 months ago, and we know they did some renovations around that time). Any thoughts/suggestions are welcome!

How long are you using the shower? 20 minutes? 10 minutes?

How long do you take your showers ? Do you have low-flow shower head ? What is the temperature setting on your hot water heater ?

There few ways to deal with this problem:

1. Install Low Flow shower head
2. Raise hot water temperature at hot water heater
3. Install another hot water heater in addition to the existing one
4. Shorter shower time
5. Wait between showers ( give it a time to re-heat water )

Problem is that when you take first shower you deplete most of the hot water. Cold water enters hot water heater to replace used hot water. It doesn't have time to re-heat to the demand temperature. The second shower won't be "hot," but only warm. Now, as this warm water is being used, cold water is again refilling water heater making existing warm even less warm

Hope that helps

Milo