First we come in and examine the tank to make sure that replace is warranted or preventive maintenance is desire by the home owner. We look from top to bottom and around the tank. Here are some things that you might look for and a trick or two to see and feel what is happening to your water heater. Always look for the apparent water in the pan but also look to see if the water has come from around the exhaust pipe if there had been a storm in the past few days.
Take a look at the water shut off on the cold water line coming into the water heater. This is usually the one on the right side of the tank water heater. If you see a white dust built up on the outside, it does not mean that it is bad it just mean that you will have calcium buildup on the value on the inside. If it is a gate value it will most of the time be very hard if not impossible to turn the water off to the tank. Keep in mind that there is always a main water shutoff to the house outside at the water meter.
Next look around the water lines leading into and out of the water heater and see how they look. Lots and rust does not mean your tank is gone but it needs to be look at by a professional. Look at the exhaust at the top and see how rusted it is. Look at the case of the water heater for rust and bumps on the outside skin of the heater. You know you have a problem with the bumps are leaking water. Look at fire box at the bottom and see if there is rust in it.
NOTE!! If your water lines are plastic red and blue DO NOT PULL ON THEM. They can break in-half at the fitting; have a professional look at this fitting and your tank at that point.
Replacement of the tank water heater is relative simple it is just not always the easiest part of plumbing to replace.
Cut the water off to the house and start draining the water heater. After drain remove the unit and re-install in reverse order. Replace TP, Gate Valve, and any water flex lines. Check and install 6 inch vent line if there is no top and bottom gas venting openings. In most area now a gas line must have sediment trap added before the gas valve. Some areas require an expansion tank on installation of every new water heater. And the expansion tank must be set for your water pressure. Remember to recycle your old water heater.
Water damage makes up a great deal of damages to houses. Remember that they are devices available that can help to prevent this and their prices are not that high. Water Cop, Flood Buster and Watts Water Buster and more on the market. Even a simple water alarm in the pan on the water heater is a great option to the screams of water is coming out of the ceiling.