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How to Install a Gas Hot Water Heater

plumber installing water heater

The typical lifespan of a water heater is between 7 to 15 years, with most lasting at least a decade. Do some research before your heater fails so you’re not scrambling at the last minute. As long as you’re handy with basic tools and have some experience soldering copper, you can easily install your own gas hot water heater.

Do Your Research

You don’t need to wait until your gas hot water heater starts to leak or has difficulty heating water before you replace it. According to the U.S. Department of Energy, the average household spends between $400 and $600 each year on heating water. If you want to save money on water heating costs, do some research and find the best heater for your family.

Along those lines, determine what size water heater you should buy. If your family has grown larger or smaller, consider adjusting your water heater size to accommodate your family’s changing needs. Measure the height of your old heater and buy one in a similar height so you don’t need to change the length of electrical, gas, and water lines. The U.S. Department of Energy offers a helpful worksheet to help you figure out what size best fits your family’s needs.

Some areas require homeowners to get a building permit to replace their water heaters. Call the local inspections department to determine if your project qualifies. When you’re done with the installation, call a plumbing or electrical inspector to check your work.

Prepare Your Area

Test Ventilation System

extinguished match

Before you install your replacement gas hot water heater, you should prepare the space. Begin by turning off the water and gas supply. From there, you should make sure that the water heater vent system works properly. To do this, close all the windows and doors and then turn on all of the gas appliances and their exhaust fans. Turn up the water heater’s temperature and wait a few minutes. Hold an extinguished match near the vent hood and see if the smoke pulls into the hood. If it comes back at you, there is a venting issue.

Drain and Disconnect Old Unit

pipe wrench

You also need to drain and disconnect your old water heater, so connect a garden hose to the drain valve and empty the tank. Remember that the water is hot. Before you remove the old water heater, check the vent pipe. If it is still in decent shape, you can reuse them with the new heater.

Use two pipe wrenches to disconnect the gas line. If the pipe is galvanized, disconnect at the union fitting. If the pipe is copper, disconnect at the flare fitting. Use two adjustable wrenches to disconnect the water lines above the tank. If the piping was soldered to the water heater, use a hacksaw to cut the pipe in a straight line.

Remove and Replace

Once you disconnect the old water heater, remove it from the area. You might need assistance to remove it if the bottom is filled with sediment. Check to see if your garbage service will dispose of your old water heater.

Place the new water heater in a spot that has at least 6 inches of space all around it. This allows for proper ventilation. Use a level to keep the water heater straight, and place plastic shims underneath if necessary. If your new water heater didn’t come with a temperature and pressure relief valve pre-installed, wrap the threads of the new valve with Teflon tape and twist it on. Don’t reuse the old one. This piece is vital because it automatically opens if the pressure or temperature becomes too high.

Solder new copper adaptors to 6-inch lengths of copper, and screw the assemblies into the hot and cold water ports on top of the tank. Install the temperature and pressure relief valve discharge pipe toward the floor. Place a bucket underneath if there isn’t a drain nearby. Cut the pipe so it’s no more than 6 inches above the bucket.

Attach the Hoses

gas hose

To complete the utility hook-up process, use a flexible hose kit with the gas hose. Use plumber’s tape and attach it to the threads of the heat trap nipples. From there, attach the hoses. Put extra plumber’s tape on the connector body threads. Make sure the fittings remain secure on the hose, and then hold the hose up to the pipe. Mark and cut the pipe, then place the compression nut and ring onto the pipe. Tighten the nut around the pipe once you push the pipe into the fitting.

If you live in an earthquake-prone area, remember to use special seismic straps to secure the heater to the wall.

Fill the Tank

temperature gauge

Once you’re done installing your new gas hot water heater, set the water temperature setting to no higher than 120 degrees Fahrenheit. Setting it higher can cause scalding. Remove the aerator from the faucet, and open the hot side. Turn the main water supply back on, and check the connections for leaks. If you have leaks, shut off the water supply and tighten the connections. Once you verify that there aren’t any leaks, fill up the tank.

Use screws to secure the exhaust hood to the venting. Take plumber’s tape and wrap the threads of the kit’s fittings with it. Place the tank’s gas control knob into the off position. Put the flare nut into the control valve, and screw the other flare nut into the gas line. Connect and tighten the hose. Turn the control knob to pilot, press the knob, and push the igniter button. When the light blinks, you should witness a small flame through the view panel.

Just like all appliances, gas hot water heaters don’t last forever. You can save yourself money by replacing your older water heater with a more energy-efficient model. Just follow these installation tips, and you can replace your old gas hot water heater with a better option for your family.

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