Removed failed 50 gallon gas water heater in the basement and replaced with Short 50 Gallon 6 year water heater. Short heater was required to correct the improperly pitched venting. Reworked water, gas, and vent lines to accomodate the new water heater and installed a new thermal expansion tank and isolating shutoff valve. New water heater was installed in a drip pan. Set expansion tank pressure to 70 psi and water heater temp to factory recommended 120°F. Tested for leaks and proper function of the system.