Water Heater Replacement: When & How To Do It

Who doesn’t like hot showers? But, what if your water heater broke and it needs replacement?Don’t you want to save some money? – Who doesn’t. So, why instead of hiring a plumber you don’t the matter in your own hands? You think you can’t do it by yourself? Well, luckily, that’s where we come in place.

When does a water heater need replacement?

Like any other appliance, water heaters wear down over time and possibly broke down if not replaced on time. Nobody likes taking a cold shower, so ideally, you’d like to be able to make your water heater replacement before it completely stops working.  What signs to look for in determining if it needs replacing before it completely stops?

  1. Tank style water heaters last, on an average, 8 to 12 years. If your water heater is pushing the 10-year mark, there’s a good chance it’s time to replace the unit. The older the water heater, the more likely it is to break down.
  2. Check your tank for rust or corrosion. Most hot water tanks are made out of steel and will eventually rust. You may even notice rust in your hot water when it’s drawn from the tap.

    If you find rust or corrosion by the temperature and pressure relief valve, and/or the water inlet and outlet connections, it’s a good indication that your tank is rusting and needs to be replaced.

  3. Over time, the sediment builds and settles inside the bottom of your water heater’s tank. If you have a gas water heater, you may have noticed a popping sound when the burner ignites. This is an indication that there’s sediment build-up.However, regardless of the fuel source, sediment build-up is a problem for both electric and gas water heaters. As it accumulates, it can clog your drain valve, and over time, it will even break down the interior of the steel tank.

    By flushing the water heater once a year you will remove the sediment and help prevent damage to the tank, as well as extend the life of your water heater. But if you’re not regularly flushing your tank, the sediment will build-up and eventually cause some serious problems.

    If the sediment build-up has reached a point where the tank can no longer be drained, it’ll be necessary to replace your water heater.

  4. Leak from the hot water tank is usually caused by an internal problem and is rarely repairable. To prevent further water damage, turn OFF both the water and power to the water heater.
  5. Something is clearly wrong if you find your water isn’t as hot as it once was, or worse, it isn’t hot at all. There may be a problem with the heating element, or the electric thermostat.

How to replace the water heater?

If you’ve determined that the problem is in your water heater (there aren’t any leaks or anything suspicious), then you can follow these steps to uninstall the old one and install new one.

Take off the old water heater

Step 1. Turn off the electricity at the circuit breaker. Disconnect the wires, but don’t forget to mark the wire connections using tape.

Step 2. Turn the water supply on, turn a faucet on hot and let it run until the water is cool. Shut off the cold water supply line and connect a garden hose to the drain valve on the bottom of the water heater.

Step 3. Open the drain valve and empty the water heater down a drain.

Step 4. When the tank is empty, remove the discharge pipe from the T&P (Temperature & Pressure) relief valve. Disconnect the water supply lines. If you must cut them, leave them as long as possible. Have someone help you remove the old tank with a hand truck.

Installing the new water heater

Step 1. Place the new water heater in a drain pan. You can avoid possible flooding by routing pipe to a drain from the drain pan.

Step 2. If your water heater did not come with a new T&P relief valve pre-installed, simply twist in the new valve now. It may be in the box or you may need to buy your own. Do NOT reuse the old valve. The T&P valve automatically opens if the temperature or pressure becomes too high for the tank.

Step 3. Install the discharge pipe from the T&P relief valve toward the floor or drain. If there is no drain underneath the pipe, put a bucket underneath to catch water dripping from the discharge pipe. Cut the pipe so it is no more than 6 inches above the bucket.

Step 4. Use a flexible hose kit for water hook-up. Apply plumber’s tape to the threads of the heat trap nipples. Then, attach the hoses.

Step 5. Apply plumber’s tape to one end of a connector body threads. Secure the fitting to the hose, and then hold the hose up to the pipe. It should have a little slack. Mark and cut the pipe, removing any burrs.

Hose held against the pipe with a little slack.

Step 6. Slide the compression nut and ring onto the pipe. Push the pipe into the fitting and tighten the nut.

Sliding the compression nut on the pipe with the fitting on deck.

Step 7. Some areas require seismic straps to prevent earthquake damage. These straps brace the water tank against the wall to keep the unit from toppling over. If you’re not in an earthquake zone, skip ahead to the next step.

Seismic straps should be installed approximately 6 inches from the top of the water heater and 18 inches from the bottom. Locate the wall studs closest to the strap measurement and drill pilot holes.

Secure one end of the strap to the stud with a socket and ratchet. If block covers the studs, use a masonry bit to create a pilot hole. Wrap the strap around the water heater and adjust the size, securing the adjustable bracket on the opposite side.  Pull the strap tight and repeat the process on the lower strap.

Illustration with of water heater secured to the studs with seismic straps.

Defer to the manufacturer’s instructions for seismic strap installation.

Step 8. To fill the tank, remove the aerator from the nearest faucet and open the hot side. Slowly turn on the water supply and check connections along the water heater for leaks. If you are leak-free, fill the tank. If you have leaks, shut off the water supply and gently tighten the connections. Repeat until the connections are secure.

Hand touching the water connections to check for leaks.

Step 10. When water runs from the faucet, the tank is full. Let the water run for three minutes to empty air and debris out of the tank.

Spurting water coming from faucet to clear air in the tank.


The tank must be completely full before connecting the wiring to avoid dry firing – which ruins the heating element.

Step 11. To connect the wiring, remove the junction box cover. Attach the ground wire to the green ground screw. Use your masking tape connection notes as a guide. Twist the wires together with wire connectors.

Removing cover plate with a screwdriver.

Step 12. Replace the junction box cover and turn the power on at the circuit. If your new water heater does not have power, turn the circuit off and check the connections.

Replace the cover plate after connecting wiring.

Step 13. Follow the manufacturer’s instructions to set the temperature to 120 degrees. It may take several hours to initially heat the water.

Temperature control knob set to 120-degrees.

Step 14. After a few hours, check the discharge pipe that runs out of the T&P relief valve. A dripping pipe usually means the pressure is too high. Turn the pressure down below 80 PSI.

Reducing pressure with a wrench.


Water coming from the discharge pipe may be hot.

Step 15. If a faucet stops running after installation, remove the aerator from the faucet in question and let the water run for a few minutes to clear loose sediment. Rinse and replace the aerator.

Removing the aerator from a faucet clogged by debris from the new water heater.

Preventing Scalds

Even with the temperature gauge set to 120 degrees, scalds are still a concern. Children, older people and those with sensitive skin are especially at risk. To prevent injury, consider installing thermostatic mixing valves.

Installed at the point-of-use faucet, fixture or appliance, a thermostatic mixing valve controls both the volume and temperature of water by attaching to both the hot and cold water supply. The settings may be adjusted inside the valve itself to provide optimum comfort.

Step 1. Turn the water supply off and use only materials (tape, pipe, solder, etc.) that are safe for potable water (because the water may be ingested).

Step 2. Solder the connections to the valve before attaching to the plumbing. Connect the valve to the hot and cold water supply and the outlet pipe. If additional soldering is needed, maintain a safe distance from the valve because excessive heat may cause damage.

Step 3. Turn the water supply on to test for leaks. Tighten and correct as necessary. Follow the manufacturer’s instructions for adjusting water temperature.

Source: Lowes

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