1. Shut off the main water valve to your house, and shut off the gas at the heater. Drain the water lines in your home by opening hot and cold taps in an upstairs faucet. Also open both taps positioned closest to the systemís lowest point. Attach a garden hose to the water heater drain valve, open the valve, and drain the tank.
2. Dismantle the flue and disconnect the gas line. Disconnect the water lines. Mark hot and cold water lines so you wonít hook up the new heater backward. If you have galvanized pipe, open unions near the unit. If you have rigid copper, cut the pipe with a hacksaw or tubing cutter just below the shutoff valves.
3. Make the cuts straight so you can tap into the lines easily with new soldered pipe or flexible water lines when you install the new heater. If you have flexible lines, disconnect them.
4. Move the old unit out with an appliance dolly.
5. Move the new water heater into place. Position it to make your gas connection as easy as possible. Flexible copper water connectors are usually the easiest way to go. Otherwise, solder rigid copper, or install galvanized pipe with a union. To save energy, install heat-saver nipples at each inlet. These temperature-sensitive in-line valves hold back water until itís needed. Follow directions, installing the cold water nipple with the arrow pointing down, the hot water nipple with the arrow pointing up.
6. Wrapthe threads with Teflon tape, and screw the valve in, either on top or near the top on the side.
7. Connect a gas (black pipe) nipple to the burner control of the water heater, and connect the nipple to the gas line. If your old flue worked well and your new water heater is the same height as the old one, you can reuse the old flue. Make sure it isnít blocked.
8. Clean out any dust, rust, or sediment from the flue. If you replace or add to the vent, use galvanized pipe fittings that are designed for venting gas.
9. Open the water supply valve. Open the nearest hot faucet about halfway, and allow the system to ďbleed.Ē First, air will come out, then the spattering of water mixed with air. When the water flows freely, close the faucet.
10. Open the access panel at the bottom of the tank, and light the pilot according to the directions printed on the water heater.