This article is for licensed plumbers to refer to. The general public can read this article for interest sake. However, you should not attempt the below.
Step 1: Remove the Old Hot Water System
Before you can install a new hot water system, its pretty logical to remove the old one! Yes, some people don’t remove the old one – but only a very few. With a fire extinguisher close to you, begin shutting off the gas valve with an adjustable open-end wrench. If you are unsure of what an open-end wrench is, best you call a professional plumber. Verify that no gas is leaking by first visually looking at the pilot light, which burns off shortly, and then smelling the area. If you do not detect a gas leak, turn the pilot switch to the “off” position and disconnect the exhaust duct located on top of the tank.
Note: Never ever use a flame to detect a gas leak.
Step 2: Drain the System
Shut off the cold-water “in” valve, and then release the water into the floor drain if one is installed. This makes the heater lighter and much easier to remove and carry.
While waiting for the water to empty, use a large pipe wrench to disconnect the gas line from the heater. To prevent “racking” the gas line, use a second wrench to provide some counter-torque. Once the fitting has been disconnected, double-checks that gas is not escaping.
Additionally, using a pair of large pipe wrenches for counter-torque, disconnect the cold “in” and hot “out” pipes in turn. This action allows more air into the heater, causing the water to drain much faster. Because longer flex pipes will be used for the new connections you will install, temporarily remove the cold-water shutoff valve. Shut off the main water located elsewhere in the household or business. To remove the valve assembly, use a pipe cutter, which scores the pipe in increments until eventually breaking through it. Also use the flex pipe to cut off the old hot “out” connector.
With the valve assembly removed and the water completely drained, it’s out with the old and in with the new hot water heater.
Step 3: Connect the New Segments of Flex Pipe
The first step to preparing the new system for installation is to connect the new segments of flex pipe. Begin by rolling Teflon tape clockwise around the cold “in” and hot “out” connectors on the hot water heater. This creates a good seal for the flex pipe, which you will tighten onto both connectors with the open-end wrench. Take the off the old system from the incoming gas supply.
Step 4: Connect a Water Supply
The first step is to connect the water heater to the water supply you must transition the water valve removed earlier. Burnish the cut ends with an emery cloth to expose fresh copper. To prepare for soldering, brush on a paste flux and twist on carefully a copper union with built-in solder. Continue joining segments of pipe with unions and two new fittings in this way. Once the correct assembly is achieved, solder using a propane torch to apply even heat to each union liquefying the solder to make a water-tight seal.
With the new valve assembly ready to go, roll Teflon tape over the new fitting and counter-torques with open-end wrenches to connect it to the cold-water flex pipe installed earlier in the process. Then solder a new union between the valve assembly and the incoming supply pipe
With the cold water supply connected to the new system, turn your attention to the hot water side. Start by soldering a new fitting to the outgoing pipe that was cut previously. After putting on some Teflon tape, connect the hot flex pipe. You’re now able to fill the heater with cold water. Turn on the main water for the house, and then the cold-water valve. While the water is running, connect the gas flex-line and reattach the duct and draft hood to vent the heater.
Once the water is completely filled, open the gas shut-off valve and ignite the pilot light, set the temperature, and the heater is ready to be utilized