Water Heater Installation Guide

The humble water heater plays an essential role in modern household comfort, but you may not think about it until it fails to deliver hot water for your daily needs. Most water heater installations last the long haul, toiling in near silence as you take showers, wash clothing and dishes, and clean up household messes for 10 to 15 years. As reliable as water heaters are, however, they do eventually come to the end of their useful life spans.

When breakdowns occur beyond changing elements or thermostats, they usually happen all at once, leading to a sense of urgency for water heater replacement. Fortunately, replacing a water heater doesn’t have to be stressful. 



Learn what it takes to replace your water heater, whether you have an electric, gas or tankless model, and discover why getting professional help for a new water heater installation can save you time, frustration and, most of all, money.

This step-by-step is a basic guide that walks you through electric water heater installation. Follow each step correctly and mindfully to ensure a safe setup. Always refer to the installation manual provided with a water heater. These instructions do not replace the printed instructions that come with the water heater or professional installation. 

Removing The Old System

Remove your old hot water heater installation with this step-by-step guide.

Step 1: Turn Off the Associated Breaker

First, turn off the breaker associated with your old water heater or remove its fuses. Open the access panel on your old water heater to get to the electrical junction box, then use the noncontact circuit tester to ensure the unit is powered down.

Step 2: Run the Hot Water Until Cool

Before you drain your old unit, open a hot water faucet and let it flow until the water runs cool. This typically takes 10-plus minutes, but it's a necessary step to prevent scalding.

Step 3: Shut Off the Water Supply

Since you don't want the tank to refill again before you drain it, shut off the water supply to the water heater. Also, turn off the unit's cold water supply.

Step 4: Disconnect Electrical Supply

Locate the wire nuts that connect the appliance service wire to your home's power wires, then unscrew them. Next, find the water heater's green ground screw and disconnect the ground wire. Lastly, remove the electric cable, disconnect the strain relief and use wire nuts to cap off your home's power wires.

Step 5: Drain the Tank

Connect a garden hose to the drain valve on your water heater, take the other end outside or put it in a sink, tub or bucket, then open the water heater's drain valve. Help this process along by turning on a hot water faucet for faster water heater drainage. Sediment buildup in the bottom of the tank sometimes prevents proper drainage, and in instances when tanks don't completely drain, you may need professional help. (Learn more about How to Drain a Water Heater)

Step 1: Run Water Until It's Cool

Drain the tank of all hot water by turning on a hot water tap. This takes approximately 10 minutes, but it reduces risks of scalding.

Step 2: Turn Off the Water Heater and the Gas

Turn off your water heater via the gas control valve, then turn off the main gas supply valve. Next, break the union between the gas lines with two wrenches, then cap the gas line and remove the gas pipe from the control valve on your water heater.

Step 3: Shut Off the Water Supply

Turn off the hot and cold water supply lines to your water heater, then connect a garden hose to your drain valve and take it outside, put it in a bucket or place it in a sink or tub.

Step 3: Install the Pressure Release Valve Discharge Line

Install a discharge pipe with 3/4-inch interior diameter, sloping it downward so it drains properly. End this pipe between 1 and 6 inches from a drain or an outside destination.

Step 4: Connect the Gas Supply Lines

Installation kits may come with flexible gas connectors. Use these to hook up gas lines to your water heater following the manufacturer's instructions. If you're unsure about working with gas lines, a professional installer may be your best bet.

Step 5: Turn On the Water, Fill Up the Tank, Purge Air and Check for Leaks

Fill up the tank to the top, then remove the aerator from the closest hot water tap and turn it on full blast. Let the water flow for 3 minutes to purge all air from the tank, and check the water connectors for any leaks while you wait.