I have a 6 year old 50 gallon lp gas hot water heater with power vent. During showering, I noticed that after about 1 minute of use, the water continually gets colder and I need to keep increasing the hot water temp (showers and faucets are single lever). This happens in each of the showers, sinks and washing machine. We experienced this problem about a year ago and had the cold water dip tube replaced (however the plumber said that the original dip tube was not damaged). Could the dip tube be bad? What other things could cause this problem. Please help, folks around here are stumped.
Rick, the water heater was drained when the dip tube was replaced about a year ago but I do not know if it was drained completely. I drained about 10 gallons out of it about 6 weeks ago when the problem occurred but did not drain it completely.