I have a 40 gallon Bradford gas water heater installed in 2004. I bought the house at the end of 2011. I do not know if the previous owner ever flushed the tank so I have not been flushing the tank. I would say 95% of the time I have no issues in the shower. I am always the first one up. Occasionally when I take a shower the water is just warm not hot. I always thought it might mean the shower handle parts need to be replaced (its a single handle for hot and cold) but today I tried running hot water at the bathroom sink and it was also not hot... just warm. I use a 1.5 GPM shower head. The water was just warm from the get go. My showers are about 15 minutes long. My thermostat on the water heater does not display in degrees so I cannot tell you exactly what temperature its set to. As I said before most of the time its fine just occasionally it surprises me with warm water. Thanks all.