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Replacing Gas Water Heaters

Though water heaters sometimes last 25 years or more, they usually give out sooner—the victims of rust and sediment. When yours fails, there’s no need to call in a plumber. Though it may seem like a complicated job, installing a gas water heater involves only two or three pipe hookups, and an electric heater requires connecting some wires. Removing the old unit is often the most difficult part of the job.

First make sure your old water heater can’t be fixed. If the tank itself leaks—not the pipes—the lining has rusted and the heater must be replaced. If your heater is not producing enough hot water, it may simply be suffering from a buildup of rust and sediment, which insulates the water from the burner and forces it to work more often to satisfy demand. Drain the heater. You may be able to flush out enough sediment to make it efficient. If it still produces too little hot water, replace it.

Caution! Precautions with Gas - If you do not have a gas shutoff near the water heater; shut off the gas to your house by turning the valve on the gas meter with a large wrench. Relight all the pilot lights in your house after you turn the gas back on. Consider adding a shutoff.

Choosing the Right Water Heater

■ Check the nameplate on the old unit and note its capacity. You’ll be safe purchasing a new one of the same size, unless you have recently installed or plan to buy an appliance that consumes a lot of hot water, such as a dishwasher. Usually, a 30- to 50-gal-lon unit will have enough capacity for an average home.

■ Units designed to heat water quickly, called fast recovery units, are more expensive to buy and operate, but they handle peak demand times better. Standard units don’t heat as fast but are more economical to run.

■ If you have hard water, consider a unit with an extra anode rod for collecting mineral deposits.

1. Drain the tank. NOTE: Shut off the main water valve to your house and shut off the gas at the heater. Drain the water lines in your home by opening hot and cold taps in an upstairs faucet. Also open both taps positioned closest to the system’s lowest point. Attach a garden hose to the water heater drain valve, open the valve, and drain the tank.

2. Dismantle the flue. Remove the sheet-metal screws and dismantle enough ductwork to give yourself room to work. Keep track of which piece of ductwork goes where and be careful not to bend it.

3. Disconnect the gas line. Many localities require that gas line be rigid pipe all the way to the water heater; others allow you to use a flexible gas line. Take apart a gas line union (as shown), or disconnect the flexible line.

4. Disconnect the water lines. Mark hot and cold water lines so you won’t hook up the new heater backward. If you have galvanized pipe, open unions near the unit. If you have rigid copper, cut the pipe with a hacksaw or tubing cutter just below the shutoff valves. Make the cuts straight so you can tap into the lines easily with new soldered pipe or flexible water lines when you install the new heater. If you have flexible lines, disconnect them. Move the old unit out with an appliance dolly.

Caution! It May Be Heavy! - If sediment buildup clogged your old heater, it will be extremely heavy. Have a helper ana a good appliance dolly, and take care not to strain your back.

5. Set the new unit in place. Move the new water heater into place. Position it to make your gas connection as easy as possible. Check for plumb and level, shimming if necessary. If the unit is in an area prone to dampness, purchase a traylike base to protect it.

6. Connect the water lines. Find out code requirements for the water lines. If they’re permitted, flexible copper water connectors are usually the easiest way to go. Otherwise solder rigid copper or install galvanized pipe with a union. To save energy, install heat-saver nipples at each inlet. These temperature-sensitive in-line valves hold back water until it’s needed. Follow directions, installing the cold water nipple with the arrow pointing down, the hot water nipple with the arrow pointing up.

7. Install T & P relief valve. You may have to purchase a temperature-and-pressure-relief valve separately. Be sure it matches the working-pressure rating of the tank as given on the nameplate. Wrap the threads with Teflon tape and screw the valve in—either on top or near the top on the side.

8. Hook up the gas. Connect a gas (black pipe) nipple to the burner control of the water heater and connect the nipple to the gas line. Be sure to install a drip leg to collect sediment and moisture from the gas line.

9. Install the flue. If your old flue worked well and your new water heater is the same height as the old one, you can reuse the old flue. Make sure it isn’t blocked. Clean out any dust, rust, or sediment from the flue. If you replace or add to the vent, use galvanized pipe fittings that are designed for venting gas. When running a horizontal section, maintain at least a W-inch-per-foot rise. Insert male ends of the vent into female ends away from the water heater so the fumes will not have a chance to escape. Fasten each joint of the vent with two sheet-metal screws.

10. Check for gas leaks. Open the gas stop valve. Test for leaks by brushing soapy water on all the connections. Watch for bubbles. If you see any, tighten the connection. If they persist, shut off the gas, disassemble, carefully clean the threads, and check again.

11. Turn on the water. Open the water supply valve. Open the nearest hot faucet about halfway and allow the system to “bleed.” First air will come out, then the spattering of water mixed with air. When the water flows freely, close the faucet.

12. Light the pilot. Open the access panel at the bottom of the tank and light the pilot according to the directions printed on the water heater. Adjust the temperature setting.

Replacing Electric Water Heaters

Installing an electric water heater is similar to installing a gas unit. The differences are that you make electrical rather than gas connections, and there is no flue on an electric water heater.

Caution! Danger! High Voltage! Working with 240-volt circuits is a serious matter. Remove the fuse or turn off the circuit breaker, and then check to make sure the power is off.

1. Remove the panel and test. NOTE: Shut off the power and water. Remove the access panel for the thermostat (usually behind the' lower panel), push aside any insulation, and lift or remove the plastic guard. Test for current with a neon tester to make sure you have turned off the circuit.

2. Disconnect, mark wires. Remove the electrical cover plate at the side or the top of the unit. Disconnect the wires and mark them with pieces of tape so you’ll know exactly where to attach them on the new unit. Loosen the screw on the cable clamp and carefully pull the cable out.

3. Connect water pipes. Install water lines. Supply lines can be galvanized steel pipe, rigid copper, or flexible water connectors. Install a ball valve on the supply line. Install a relief valve, and attach an inlet pipe.

4. Make the electrical connections. Connect the black and white wires with wire connectors, and attach the ground wire to the ground screw. Tighten the screw on the clamp to hold the cable in place, gently push the wires inside, and replace the cover plate.

5. Set the thermostat. Set the water heater to the temperature you want. Press the reset button, and replace the plastic guard, insulation, and access panels. Turn the water on.

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