A water heater is an appliance you do not know you have until it breaks. You probably found this site searching for help how to get a warm shower tonight. Your kids are probably complaining already. Because of this time pressure people often times overpay companies to install sub standard units at a very high cost. A water heater is an appliance like your dishwasher. Why would you allow a contractor to install a "name brand" unit you have never seen before?
Take a step back and breath. Having only cold water for a few days is not the end of the world. You can do this yourself; or at least you can do most of this yourself.
Shift your focus on searching for a good unit to install. All the home centers and appliance stores sell water heaters. Find the specifications of your old unit (capacity, gas/electric, dimensions) and find a similar unit. Look for certified water heaters with high R-values. Efficient water heaters are well insulated water heater.
Purchase the heater, a drain pan (if you don't have one already), and installation nipples (short pipes, sold as a set at the home centers), and two flexible copper pipes for connecting the heater to the home's water system. The home centers are open late. They cater to people like us who make 4 trips in single night just to get that missing part. If you have a gas water heater,pick up a new flexible connection pipe that fits your model heater. These are sold as a set as well.
Installing an Electrical Heater
1) Installation begins with draining the old heater. Connect a garden hose to the drain valve and drain the heater's content to a suitable drain. Most homes have a drain in the room the water heater is located in. Otherwise use a shower or out the front door into your planters.
2) Turn off the breaker in the electrical panel of the home. Disconnect the wire at the water heaters' electrical panel. This will require you to loosen 3 wires. Make sure noone in the home will turn on the breaker on while you are working on the heater.
3) The next two connections you need to undo are the warm and cold feeder pipes. Often times all it takes is loosening a compression nut. If this is not possible, cut the copper pipes with a hacksaw as close to the heater as possible.
4) The last connection to undo is the pressure relief valve. Simply cut through the pipe connected to it, or undo one of the joints in the pipe. If the pipe is copper, use a torch to disconnect a union.
5) Remove the earthquake straps in such a way the heater can be moved, but the straps stay attached to the house. The straps will be reused on the new heater.
5) At this point the water heater is no longer connected to your home. Remove it. Install the a new drain pan, if there isn't one already in place.
Trust me, you want this pan. 10 years down the road when the heater leaks, these will be best $20 you have spent in a long time.
6) Prepare the new heater by installing the pipe stubs. Apply Teflon tape to the pipes and install them using a pipe wrench. Move the water heater in place.
7) Connect the hot and clod water pipes to the heater. Take care to connect pipes to the correct one on the water heater.
The flexible copper pipes are your best friend here. Connect them to the heater's stubs using the compression nuts that come with the pipe and Teflon tape. Connect the other end to your home's plumbing.
Typically you plumbing will end in threaded connection similar to the one on your heater. If this is so, you can use the flexible pipe's compression nut. Otherwise you have soldering to do. Find the treaded connector that should be on the pipe at the home center and any other parts you need to get the connector in the right place. Connect it using the proper pipe soldering technique, Connect the flexible pipe. At least next time everything will be simple.
8) Connect the pressure relief pipe to the new heaters safety valve. How this is done depends on your home's plumbing. Get new pipe and a few connectors at the home center. Typically you will need a new threaded connector and a straight connector to connect to the old pipe you cut. Install and solder the pipes.
9) Reinstall the earthquake straps.
10) install the electrical wires. The three wires in the bundle need to be connected to the right terminals. Consult the owners manual of your heater. The cover of the heater's electrical panel should show a wiring diagram.
11) Turn the water back on and let the heater fill. When it is full, turn the power back on. You are done. You'll have hot water in about an hour.
Installing a Gas Heater
The install steps for a gas heater are the same, except for the power source. It's actually simpler to install a gas heater. If you are uncomfortable with working on gas, leave this step for a contractor. This job should take about 5 minutes. If you smell gas at any point, leave the area immediately and call the gas company.
1) Turn the gas off. Remove the flexible pipe that connects the heater's gas input to the home's gas pipe.
2) Installation requires doing everything in reverse. Use pipe putty on all connections. Install the adapter on the heater, and the new flexible pipe.
3) Turn the gas back on, and test for leaks. Apply Light the pilot light following the instructions on the heater.
Overall this project is simple to do, if the home's plumbing is already set up for easy water heater replacement. At any rate, skip the expensive water heater replacement companies. Buy the heater yourself and do as much work as you are comfortable with. Hire your favorite handyman to finish the work. You do not even need a plumber for this work. Just ask your guy, if he has done this before. There is no such thing as a water heater specialist.