Water Heater Installation Basics

2-4 hours

Hot water is a must for any home, and this guide will show you how to install a hot water heater

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Installing a new water heater begins with the old heater. If you've got an electric heater, replace it with an electric heater, unless you're willing and able to run gas line and exhaust vents. If you've got a gas heater, stick with gas, unless your breaker box has room for (and you're willing to install) a new 240-volt circuit.

Whether the heat source is gas or electricity, make sure you shut it off before beginning work. Electric heaters can be cut off at the breaker box and may have an additional breaker closer to the heater. Gas heaters will have a cut off valve, usually with a red handle, along the line leading to the hot water heater. This guide will teach you the best and safest way to install your new water heater.


Remove the Old Water Heater
Remove Old Water Heater - Water Heater Installation Basics

Turn off the water and gas supply valves and/or the power. Remove the electrical supply access plate at the top of the water heater. Check the connections with a continuity tester to make sure the power is off. Attach a garden hose to the drain valve and empty the tank. Using two pipe wrenches, disconnect the gas line at the union fitting if the pipe is galvanized or at the flare fitting if the gas supply line is copper. Close the line with a cap while working to prevent any chance of gas leak.

Disconnect the Water Lines
Disconnect Water Lines - Water Heater Installation Basics

Using two adjustable wrenches or pipe wrenches, disconnect the piping above the tank. If the piping has been soldered into place, use a tubing cutter to cut it.

Set the New Water Heater
New Water Heater  - Water Heater Installation Basics

Install the water heater in an area where it won't be cramped. Leave at least 6" of clearance around it for ventilation. Don't set it next to flammables. Turn the water heater so that access to the burner and controls is unobstructed. Place a level on the side of the water heater and plumb it with plastic shims.

Wrap the Heat Trap Fitting Threads
Wrap Heat Trap Fitting - Water Heater Installation Basics

Use Teflon tape on the pipe threads. These fitting are directional and must be installed properly. Both have arrows showing the correct direction for installation. Attach the blue-coded fitting to the cold water inlet with the arrow facing into the water heater. Attach the red fitting to the hot water outlet with the arrow pointing away from the water heater. Tighten using two pipe wrenches or adjustable pliers.

If You Removed the Shutoff Valve, Replace It
Removed Shutoff Valve, Replace - Water Heater Installation Basics

Sweat solder the shutoff valve to the end of the cold water supply pipe. Use a MAPP torch and lead-free solder to connect the valve to the supply line. Solder with the valve in the open position to avoid overheating the parts.

Install the Water Lines and Pressure Relief Line
Lines Pressure Relief Line - Water Heater Installation Basics

Use two adjustable wrenches to connect the pipe from the pipe run to the water heater. Turn on the main shutoff and open all line valves. Open all the faucets in the house and run the water until it flows steadily from them. Close the faucets.