Originally Posted by wmtire
As wmtire suggests, check the bypass (crossover) valve.
Little hot water or luke warm water is one of the most asked about questions this time of year after folks are coming out of winterizing.
Also understand, not knowing what flow rate shower head you have... at the typical 1.5-2.0 GPM flowrate of many shower heads, the pump (or city water) can easily deplete a full hot water tank in minutes.
At 1.5 gallons per minute you can deplete the 6 gallon tank in 4 minutes using all hot water or about 8 minutes using a mix. A 2.0 GPM shower head (what most Oxygenics are) is even less.
Another thing you can do... If your water heater is both electric and propane, you can turn on BOTH sources of heat and get the recovery rate much quicker.
Recovery or the duration of hot water is also very dependent on the ambient temperature of the water source going into the tank. Many underground water sources at this time of year are still very cold. Come the heat of the summer and it's a different story.