If you plan on changing your old water heater for one that is similar here are the steps you will need to follow to install the new water heater.

Step one:
Once you have shut off the water and gas or power supply to the water heater tank you will need to connect a hose to the drain valve at the bottom of the tank. Before opening the valve, make sure, you run the hose to a nearby drain or to the outdoors. After getting, the hose in place open the valve on the bottom of the water heater. You will also need to use two wrenches to unscrew the inlet and outlet fittings from the top of the tank.

Step two:
On a gas water heater, you will need to shut off the gas inlet valve and use two wrenches to disconnect the union or flare fitting between the gas supply and the inlet valve. You will also need to remove the flue hat that expels gases into the flue at the top of the tank.

Step three:
Now you can remove the old unit once all of the water has drained out of it.

Step four:
After you remove the old unit, you will need to set the new one in place. Make sure when setting it in place that you place the controls and burner where they are accessible. You want to ensure that there is at least 6 inches of clearance around the perimeter of the water heater. There should also be no flammable materials in close proximity to the water heater.

Step five:
Use a level to check it for plumb. If you need to you can shim the base with pieces of asphalt shingles or plastic wedges.

Step six:
Wrap the threads of the heat trap fittings with pipe-wrap tape. Then screw the fittings into the water heater. Make sure that blue is screwed into the cold-water inlet and that red is screwed into the hot water outlet. You also want to make sure that the arrows marked on the fittings point in the direction of the water flow.

Step seven:
Now install new flexible connectors on the water inlet and outlet pipes. If your hot water heater did not have a shutoff valve on the cold-water side, you will want to install one before you connect the water heater. After all of the connections are complete, open the shutoff valve so you can fill the water tank. While the tank is filling, go around the house and open several hot water faucets to help bleed off air in the pipes.

Step eight:
Assemble the gas pipes to the water heater. Spread pipe dope on the threads and screw together the parts. You will need to tighten them with one pipe wrench on the pipe and another on the fighting.

Step nine:
Follow the directions from the manufacturer for connecting the unit with the gas supply tubing because it can be different for each water heater. Once it is connected turn on the gas. Check all of the connections for leaks by brushing soapy water on them and watching for bubbles.