How to Install Water Heater

In a perfect world, the best time to install a water heater would be when your old one is still working and you have plenty of time and money to get a new one. Of course, this is rarely the case, and chances are your old, rusty heater will stop working in the middle of a cold winter’s night. When this happens, the best option is to call a professional. Sometimes this is not possible, and homeowners must do the water heater installation themselves. If this is the case for you, don’t panic. Luckily, it is not that difficult a task, even if you don’t consider yourself to be a handyman.

Fitting  water heater

Fitting water heater

When choosing your replacement water heater, make sure you select the same fuel type (gas or electric.) This may seem obvious, but you’d be surprised at how many people don’t make that distinction before buying. If you’d like to change the size, though, you can certainly do that. For instance, if you had a 40 gallon tank, but want to increase to 50 gallon, this is perfectly acceptable. Just make sure you have enough clearance between the wall and the heater.

Before Installing the New Heater

Before you remove the old heater, measure the dimension between the hot and cold pipes on the top of the heater. Try to make sure that the new one has the same dimensions, or as close as possible.

Check the plumbing to make sure there is a gas union (for gas heaters), and ensure that there is a cold water shutoff inlet pipe, as well as a union connector for the hot water outlet pipe. Most professional plumbers ensure this is all in place when installing water heaters, so you should have everything in place.

When your new heater arrives, ensure that you have the necessary equipment and manpower to get it where it needs to go (usually in the basement.) This may require renting an appliance dolly, and bribing at least one friend to help you.

Before doing anything, you need to shut off the utilities going to the heater. Shut off the main water supply that runs into the existing heater. If you have an electric heater, turn off the electricity that runs to the heater by removing the fuse or disabling the circuit breaker that runs to the heater. If it is gas powered, ensure that the pilot light is out after you shut off the gas valve.

Draining the Tank

Once the water has been shut off, you’ll need to drain the old tank before removing it. There are several steps involved in doing this:

• Open the hot water faucet that is closest to the heater

• Attach a hose to the valve on the heater

• Place the opposite end of the hose on a floor drain

• Open the valve slowly, so the drain doesn’t clog with sediment that may be present

Tools Needed

You will need the following tools in order to disconnect your old heater, turn off the utilities and install the new one:

• Tongue and groove pliers

• Pipe wrench

• Slip joint pliers

Once the water lines, electric or gas service, and flue have been disconnected, the old heater is ready to be removed. To do this, follow these steps:

• Move the old heater onto a dolly (you may have to have a friend help you with this)

• Clean the floor where the old heater was

• Move the new unit to where the old unit was; be sure to line things up with the existing plumbing pipes.

• Use a level to make sure that the new unit is securely in place, and not on an angle.

Install the New Fittings

Now that you have the new heater in place, you’ll have to install the various fittings. These include the temperature valve, pressure relief valve, and the discharge drain pipe. Read the manufacturer’s instructions carefully when installing these fittings. For copper, be sure to use Teflon tape; for galvanized fittings, use joint compound or pipe dope.

Next, you’ll have to install the plumbing lines. If the new outlets do not line up exactly with the old ones, use flexible copper lines to make sure things line up properly. If you don’t already have cold water shut off valve, install one, as per manufacturer’s directions.

After the water lines have been installed, it’s time to connect the fuel source. If you have a gas heater, connect the gas burner control valve to the gas line. Check for leaks by turning on the gas valve and applying a soapy solution onto the union and joints. If you see bubbles, you’ll need to tighten the connections; if you can’t tighten it you will need to call the gas company and/or a professional plumber. If there are no leaks, you can then attach the flue. For electric heaters, connect the ground wire and power lines to the junction box.

Now that all the connections have been made, and utilities have been turned on, it’s time to fill the tank with cold water, and turn the unit on. The main water supply should now be turned on, and the pilot light should be lit, if it’s a gas heater. The thermostat on the unit should be set between 110 and 130 degrees Fahrenheit.


The cost of installing a hot water heater yourself will be much less than if you call a professional. Plan on spending anywhere between $100 and $500 depending on the size of tank you choose, and what fuel source you have.

Where to Buy Parts/Heater

You can do some research online to find local hardware and home renovation stores that sell water heaters as well as the various tools you’ll need to install it. Big box home renovation stores often offer the best prices, and they can also help with questions you may have.

Local Building Codes

Before you do anything, you have to make sure that you are operating with your local codes and laws. If you are unsure, call your city’s offices and ask about any restrictions or specific procedures that you need to follow.

Basic Maintenance

It is always a good idea to have an inspection of your heater at least once a year. For best results, hire a professional. If you are doing the inspection yourself, make sure you check for rust or corrosion of the pipes among other things. Check for gas leaks (if a gas heater) and for frayed wiring, which could be a fire hazard.