After removing and draining the old water heater, hooking up new flex pipe segments, connecting to the gas supply (unless the heater is electric) and linking to the water supply complete replacement of a hot water heater. Because of the heavy lifting involved, it is wise to enlist an assistant.
Removing a hot water heater begins with cutting off the power, by either turning the gas valve off with a wrench and waiting for the pilot light to burn out, or by turning off the circuit feeding the water heater and unplugging it from the wall. After smelling the area for gas and ensuring there is no leak, the next step involves turning the pilot switch off and unhooking the exhaust duct, usually found on top of the tank.
Turning the "in" valve for cold water to the off position and letting the water go into the floor drain takes the majority of the weight out of the heater. If the heater is fueled by gas, this is a good time to unhook the gas line from the heater. The same process follows for the pipes taking water in and out of the heater. It is now time to turn the main water supply off to the house.
After taking the valve assembly off with a pipe cutter, lift out the old water heater. When the new heater is in place, roll Teflon tape around both "in" and "out" connectors in a clockwise direction to make a seal for the flex pipe when you connect it to the new outlets.
It's also time for a new gas line running to the pilot box (although this is not necessary with an electric heater). Replacing the old gas supply fitting with a new one, applying a layer of Teflon dope before installing and tightening the new fitting, complete that part of the process.
The last step involves preparing the water valve that was removed. After cutting old fittings off using a pipe cutter, rub the cut ends using an emery cloth to show new copper and brush a paste flux before twisting on copper unions with solder built in. Connect the pipe segments with unions and a pair of new fittings. Use a propane torch to heat each union and turn the solder into a liquid, forming a seal.
This new valve assembly needs Teflon tape over the fitting before the user connects it to the cold-water flex pipe and then solders a new union between the supply pipe and the valve assembly. Repeating the process for the hot-water flex pipe prepares the heater for water. It is now time to connect the gas flex-line and connect the draft hood and duct again so the heater has venting. If the heater is gas, it is time to open the gas shut-off valve, turn on the pilot light and set the desired thermostat. If the heater is electric, the only step is to plug it in and set the thermostat.