How to Install an Electric Water Heater

How to Install an Electric Water Heater

A water heater, especially an electric model, is a very simple device. Unfortunately, such simplicity doesn’t really extend to its installation.

A water heater, especially an electric model, is a very simple device. Unheated water enters one side of the tank. The water is heated by a couple of electric resistance elements that extend from the side of the tank into the middle of the water. And then on demand the water exits from the other side of the tank.

Unfortunately, such simplicity doesn’t really extend to its installation. While far from difficult, installing an electric water heater does involve plumbing and electrical work, which may be enough to put off quite a few people. It shouldn’t. The skills required for a job like this are not nearly as demanding as they are for other common homeowner pursuits like refinishing furniture or growing a successful vegetable or flower garden.

Plan your installation on paper first. This is a great way to minimize the number of fittings you need and the number of trips to the hardware store to buy the things you forgot.

For this job, we were replacing a tank and moving its location as part of a larger remodeling job. If you’re just putting a new tank in the same place, you’ll have even less work to do. Begin by removing the tank from its box and reading all the product literature that comes with it. Make sure to incorporate any specific manufacturer instructions into your plans, especially if not doing so voids the product warranty.

Step 1: Build a Platform

Select a convenient spot for the tank and place two or three concrete blocks on the floor. These blocks help prevent damage from minor floods and make getting at the drain much easier.

Step 2: Center the Tank

Next, slide the tank on top of the blocks making sure to keep the drain faucet to the front. Rock the tank back and forth slightly to make sure the blocks don’t move. If the blocks do move, or the tank rocks on top of the blocks, reposition everything until the tank is stable.

Step 3: Soldering Basics

How to Install an Electric Water Heater Soldering copper tubing and fittings is really one of the easiest building skills to acquire. All you need (besides the tubing and fittings) are a propane or Mapp gas torch (we prefer Mapp gas because it burns hotter and melts lead-free solder better), a tubing cutter, some paste soldering flux, several pads of steel wool, a wire brush to clean the ends of the fittings and some lead-free solder. All of these items are commonly available at local hardware stores and home centers. The rules are simple: The mating surfaces must be cleaned thoroughly and covered with flux, the tubing cuts have to be absolutely square and the fittings can’t be bent or distorted.

The place to begin is by cutting a 6- to 8-in.-long piece of 3/4-in.-dia. tubing for the cold water entrance line on the tank. Use a tubing cutter, not a saw, and keep the wheel square to the pipe as you work.

Next, clean the end of the tubing with a piece of steel wool. Rub clean an area at least 1 in. long and make sure that only a bright copper color can be seen when you’re done.

Then cover the cleaned area with some soldering flux and put the piece aside.

You can also use steel wool to clean the inside of all your fittings, but it’s much more convenient to use a simple wire brush designed for the purpose. Just insert the brush into the end of the fitting and turn until the surface is clean.

Add flux to the inside of the fitting, and then slide the fitting over the end of the tubing piece.

Begin heating the joint by turning on the torch and adjusting the flame so the inner blue flame is about 3/4 in. long. Bring the tip of the flame to bear directly on the top of the joint and heat this area until the flux melts and burns out. You don’t have to move the torch around the joint. Copper is a great conductor of heat and keeping the flame in one position is all that’s required to heat the entire joint.

As soon as the flux disappears, touch the top of the joint with some solder. If the tubing is hot enough, the solder will melt right away. If not, simply lift off the solder, keep heating the joint and try again.

Once the solder starts to melt, keep pushing the solder into the joint until it drips out the bottom. This means the joint is full. Immediately remove the flame and wipe off any excess solder with a soft rag. Be sure to wear heavy gloves to prevent burns.

Because we wanted to be able to easily move the tank for servicing or repair we decided to put a union fitting on both the cold and hot lines as they left the tank. To install these unions, simply clean all the tubing ends and fittings as before, add some flux and solder the parts.

Once this assembly is complete and cool to the touch, use Teflon tape to seal the pipe threads on the tank nipple. Imbed the tape in a clockwise direction.

Thread the tubing and adapter assembly onto the tank and then tighten firmly in place with an adjustable wrench.

Then join the two halves of the union together place and tighten the nut firmly.

Next, clean and flux a shutoff valve for the cold side and slide it over the tubing end place and solder it in place. We used a ball valve for this purpose but a gate valve with sweat fittings on both ends can also be used.

Step 4: T&P Valve

The T&P valve (temperature and pressure relief valve) is a safety device that creates a pathway for the water to escape if the pressure inside the tank builds to a dangerous level for any reason. It’s important that the valve you buy is rated the same as your water heater. The product literature for both will describe what’s required. In our case, we simply matched the ANSI (American National Standards Institute) rating numbers of both.

To begin the installation, temporarily thread the valve into the tank and take a measurement between the bottom of the valve and the floor place.

Deduct 4 in. from this measurement and cut a length of tubing to match. Once your measurement is taken, remove the temperature and pressure relief valve. Then cover the threads with Teflon tape, stretching it into place.

Reinstall the valve in the tank using an adjustable wrench. Make sure that the open end of the valve points down.

Cut the relief valve tube to length and solder a male adapter to one end. Cover the adapter threads with Teflon tape.

Thread the drain tube into the relief valve and tighten. The open end of the tube should be 3 to 4 in. above the floor.

Step 5: Electrical Power

A water heater always requires a separate 220-volt circuit and in our case a 30-amp circuit breaker and 10/2 (with ground) circuit cable. These were already in place on our job, but the cable ended nearly 20 ft. away from our new tank location.

We brought new cable, from a joist-mounted junction box, to the new tank location by boring holes through the middle of the overhead joists and running the cable along the side of the joists where convenient. Be sure to staple the cable in place every 2 ft.

To gain access to the electrical wires in your tank, remove the covering plate on the top place. and pull out the black and white wires that you find there.

Locate a knockout on the top of the tank and force it down with a screwdriver and hammer. Break it off with pliers.

Slide the threaded end of a conduit connector into the knockout hole and tighten it in place with the connector nut.

Next, measure the distance from the top of the tank up to the joists above and add about 4 in. so the conduit can be attached to the side of a joist or a piece of blocking nailed between two joists.

Once the conduit is cut, slide the free end of the cable into the top of the pipe and pull the cable out the bottom.

Then fish the cable end through the connector and into the tank opening and slide the conduit into the connector.

Tighten it in place with the connector screw and attach the ground wire from the cable to the grounding screw inside the tank opening.

Join the two white wires together with connectors and the two black wires together with connectors. Replace the covering plate and your installation is done.

Check your work by first filling the tank with water and making sure that there are no leaks in your plumbing job. Remember to close the drain valve before turning on the water. Only when the tank is full should you turn on the circuit breaker and send power to the heating elements. If you turn on the elements before the tank is full of water, they will be ruined and will have to be replaced.

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