Electric Hot Water Heaters - How to Install a Water Heater

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

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A handy person can install an electric water heater. People do it everyday. The real question is whether their installation complies with building codes and was done in a manner that allows the appliance to be more easily serviced.

Is this job for you? It is if you can check these off:

Suppose you don’t want to install the appliance yourself. Instead you’ll be working with a plumber who will handle the installation. We think the tutorial below can still be of service. The best customer, as they say, is an informed customer.

A storage-type water heater, especially an electric model, is a very simple appliance. Unheated water enters it and 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 out a pipe from the other side of the tank.

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. Begin by removing the tank from its box and reading the product literature that comes with it. Incorporate specific manufacturer instructions into your plans, especially if not doing so voids the product warranty.

While reading the instructions, keep in mind, that local building codes (meaning your municipality, county or state codes) will have the final say about what constitutes a correct installation. For example, water heaters that are not located in the basement (and sometimes even then) are often installed on a pan today. This is to capture a small but steady leak that can damage the building. Also, expansion tanks are often plumbed into the cold-water supply line that supplies the heater. As water is heated, it expands, and anticipating this water movement, plumbers sometimes install an expansion tank on the cold-water line to absorb the pressure this expanding water creates (Note: this is usually the case for homes where there is a pressure reducing valve installed on the incoming water service line). Expansion tanks are supported with a strap or a code-approved shelf such that its weight is not held up by the pipes leading to the water heater.

Also, all water heaters are installed with a temperature and pressure relief valve (in plumber’s short hand, the T&P valve) to prevent over temperature and pressure from turning the water heater into a dangerously pressurized appliance. When the pressure in the tank approaches a dangerous level, the valve will discharge water to a pipe and this brings the pressure down. The International Residential Code (a building code that many states and municipalities follow) takes pains to explain how to connect this discharge pipe and lists 14 different specifics about it. It’s spelled out in Chapter 28 of the 2021 International Residential Code. You can look up a digital version of the code here. Below we show a simple installation of a T&P valve.And most importantly: Turn off the circuit breaker that serves the water heater before beginning work. Use a non-contact voltage test pen or an inexpensive multi-meter to check that electrical wiring is not energized before disconnecting any electrical leads to an existing heater or connecting the new heater to its power source.

Assuming that you are replacing an existing heater, shut off the power to the heater at the service panel, check that the wiring is de-energized, drain the heater, disconnect its plumbing and electrical connections, and remove it.

With the appliance out of the box, and your tools and materials ready, decide on the appliance’s location. If you’re replacing a water heater, and the existing location seems appropriate, it makes sense to put the water heater right back where it came from. Moving it to another location requires more work.Some plumbers elevate a water heater in order to make it easier to drain and to service. It also raises the appliance to protect it from basement flooding (gas-fired water heaters are often elevated above the floor; again building codes have a lot to say about those appliances). Only you can decide whether to exercise this option and if the extra work and cost involved is worth it (if it’s code required where you are, you’ve got no choice). Use a water heater stand to do this, and secure the appliance to the wall with a minimum of two water heater straps. In California, these straps must be rated for seismic protection. In other areas of the country, so-called plumber’s pipe hanger strap may be suitable for this. Check with your building department.

You can hook up a water heater to your home’s plumbing with copper tubing, corrugated flexible metal connectors, or flexible plastic tubing known as PEX (or some combination of those materials). If your home already has PEX or you decide to use PEX for the first time, reviewing manufacturer’s literature can help you understand the specifics of working with this material. For example, see page 10 of this manual by Zurn, a PEX manufacturer. Also, there are also plentiful YouTube videos on using PEX.

Frankly, though, the point of installing a water heater is to replace the appliance and not give yourself a crash course in modern plumbing materials. Given the learning curve necessary to use PEX, it may make more sense to simply solder copper tubing and fittings to connect to your home’s plumbing or to use Sharkbite fitttings.

Soldering copper tubing and fittings is really one of the easiest building skills to acquire. You can use soldered fittings to connect to the house’s plumbing, to install a shutoff valve in the cold-water line leading to the heater, and to connect the T&P valve.To solder, all you need (besides the tubing and fittings) are a propane or high-temperature gas torch (this high-temperature gas is known generally as Mapp gas , and it burns hotter and melts lead-free solder more readily than pure propane), a tubing cutter, some paste soldering flux, plumber’s abrasive cloth, a wire brush to clean fittings and some lead-free solder. If you prefer shopping in a brick-and-mortar store, all of these items are available there.

The procedure is simple. Cut pipe to length with the tubing cutter, clean the ends of the pipe and the inside of the fittings so that they are bright and shiny. Spread flux on the mating surfaces. Heat the parts with the torch by directing the flame at the fitting (or the pipe) but not directly at the joint. When the flux begins to smoke, take the torch away and touch the solder to the joint. 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. The Copper Development Association, a trade organization has excellent step-by-step photos of the process here.

Once the joint is completely soldered, remove the flame, and wipe off excess solder with a soft rag. Wear leather gloves to prevent burning your hand.

If the incoming water line to your water heater is not served by a modern ball valve shutoff, now is the time to install one. Again, you have options. These can range from a traditional soldered ball valve (known to plumbers as a sweat ball valve) that requires a multi-step installation to one-piece Sharkbite fittings equipped with a shutoff valve that simply threads into place.

If you solder on a ball valve, there’s a few things to know. First, carefully dry fit the components starting with the threaded fitting to connect the incoming cold-water line to the tank. Connect a piece of tubing to this fitting and tighten it onto the tank. Slip the ball valve onto the tubing.

Next, position the ball valve on the tubing and assemble the rest of the components. Measuring and marking as necessary.

Remove the tank fitting and copper tube and solder them together, and solder the ball valve to the inlet tube. Reinstall the sub-assembly of these pieces on the tank then proceed to sweating together the remaining tubing and fittings that will connect the water heater to the cold water line. Remember, to use pipe thread tape before tightening the fitting to the tank.

The most important component on the water heater is its T&P valve. Many new water heaters today come with a valve factory installed. If possible, you should select such an appliance. But if your’s does not have the valve installed on it, you must buy and install a valve that has a rated discharge capacity that is greater than the water heater’s BTU-input rating. The product literature for both the water heater and the valve will describe what’s required. Using plumber’s thread tape, tighten the T&P valve onto the tank.

Next, take a measurement from the valve to determine the length of the piece of copper tubing that will connect to it. Here we show a T&P valve installed on the tank’s side. Other T&P valves mount on the top of the tank. The measurement that you take will depend on the specifics of how the discharge tubing runs from the valve. Again, there are multiple ways this can be handled; see Section P2804.6.1 of the IRC building code that describes this. In most cases, it’s very simple. Either this tubing will run straight down and discharge not more than 6 inches above the floor, or it will run horizontally and then down to its discharge point (the discharge point can even be outdoors or into the pan in which the water heater is sitting). The important thing is that the discharge point cannot be concealed behind or under something. It must be readily visible to the building’s occupants.

An electric water heater always requires a separate 240-volt circuit; in many cases it reqiuires a 30-amp circuit breaker and 10/2 with ground circuit cable (note: 10/2 with ground means two 10-gauge wires and a separate bare ground wire). Read the installation or other manufacturer literature that is supplied with your water heater to be sure that that the breaker and wiring to the appliance are sized correctly. When in doubt, call an electrician.

Assuming that you are replacing an old failed water heater with an identical new appliance, then the electrical installation should be straight forward. To gain access to the electrical wires in the water heater’s tank, you will remove the electrical covering plate, usually located on the top of the appliance, then hook up to the existing electrical supply. To do this, you connect like colored wires to each other using wire connectors and leading the ground wire on the incoming power to the green ground screw below the cover plate. If the incoming ground wire has a hook bent into it, all you need to do is loosen the ground screw on the water heater, slip the hook under the ground screw, then tighten the screw down on the ground wire.When the electrical hook up is complete, check that the water heater’s drain valve is closed and if not, close it. Next, fill the appliance with water by opening the valve that supplies the appliance. Important: Do not restore power to the water heater until the appliance is completely filled with water; energizing the water heater while it is partially filled or empty will ruin the heating elements. Once the appliance has been filled, open a hot water faucet nearest the heater and allow the trapped air created by the installation to work out of the plumbing. With the appliance filled, shut off the water faucet and restore power to the heater. Let it warm up and open the warm water faucet again. Check the water temperature. Most heaters are set to supply water at 120 degrees F. If you want the water temperature higher (be aware of the danger of scalding hot water), adjust the appliance’s temperature controls accordingly.

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