How to Install a Water Heater

Installing a water heater is a significant DIY project - but it is within reach for a confident homeowner with basic plumbing skills. This guide covers the complete installation process for a tank water heater, including what to check before you start, the tools you need, and a step-by-step walkthrough.

Important: Many jurisdictions require a permit for water heater installation. Check with your local building department before starting. Some areas also require a licensed plumber for gas water heater installation.

Before You Start: What to Check

• Confirm the new heater matches the fuel type of your existing setup (electric or gas)
• Check that the new heater fits in the available space - measure height, diameter, and clearances
• Verify your electrical panel has capacity for an electric heater (typically 240V, 30A circuit)
• For gas heaters, confirm the gas line size is adequate for the new unit's BTU rating
• Check local permit requirements

Tools and Materials You Will Need

• Pipe wrench
• Adjustable pliers
• PTFE thread seal tape
• Garden hose
• Bucket
• Voltage tester (electric heaters)
• Pipe cutter or hacksaw (if modifying pipes)
• Flexible supply lines (if not included)
• Earthquake straps (required in seismic zones)

Mr. Pen 10-Inch Pipe Wrench - for connecting and tightening all pipe fittings.

Gasoila Yellow PTFE Thread Seal Tape - seal all threaded connections during installation.

Flexzilla Garden Hose 50ft - drain the old tank before removal.

Rubbermaid 12-Quart Bucket - catch residual water during removal.

Step 1: Drain and Remove the Old Water Heater

1. Turn off the power (electric: circuit breaker) or gas (turn control knob to PILOT)
2. Turn off the cold water supply valve at the top of the heater
3. Connect a garden hose to the drain valve and drain the tank completely - open a hot water faucet to speed draining
4. Disconnect the electrical wiring or gas line from the old heater
5. Disconnect the cold water inlet and hot water outlet pipes
6. Remove the T&P valve discharge pipe
7. Move the old heater out - tank heaters are heavy when empty; get help or use an appliance dolly

Step 2: Position the New Water Heater

1. Place the new heater in position - allow the clearances specified in the installation manual
2. In seismic zones, strap the heater to the wall with earthquake straps before connecting anything
3. Make sure the heater is level

Step 3: Connect the Water Lines

1. Wrap all threaded fittings with 3-4 layers of PTFE tape before connecting
2. Connect the cold water inlet line to the cold port (usually marked blue or C) at the top of the tank
3. Connect the hot water outlet line to the hot port (usually marked red or H) at the top of the tank
4. Use flexible supply lines if the existing pipes do not align perfectly with the new heater's ports
5. Tighten all connections with a pipe wrench - firm but not overtightened

Step 4: Install the T&P Relief Valve

1. Wrap the T&P valve threads with PTFE tape
2. Thread the valve into the designated port on the tank - usually on the side near the top
3. Tighten with a pipe wrench
4. Connect the discharge pipe - it must run downward and terminate within 6 inches of the floor or into a drain. Never cap or plug the discharge pipe.

Camco T&P Relief Valve - install a new T&P valve with every water heater installation. Never reuse the old valve.

Step 5: Fill the Tank

1. Make sure the drain valve is fully closed
2. Open the cold water supply valve
3. Open a hot water faucet somewhere in the house to purge air from the tank
4. Wait until water flows steadily from the faucet - this means the tank is full
5. Close the hot water faucet
6. Check all connections for leaks

Step 6: Connect the Power or Gas

Electric Water Heater

1. Connect the wiring to the heater's junction box - match wire colors (black to black, white to white, green or bare to ground)
2. Secure the junction box cover
3. Turn on the circuit breaker
4. Wait 1-2 hours for the tank to heat fully before testing

Gas Water Heater

1. Connect the gas supply line using approved gas fittings and pipe dope or PTFE tape rated for gas
2. Turn the gas supply on
3. Check all gas connections for leaks using soapy water - bubbles indicate a leak
4. Light the pilot light following the manufacturer's instructions on the label
5. Set the temperature dial to your desired setting
6. Wait 30-60 minutes for the tank to heat

Step 7: Final Checks

• Check all water connections for drips
• Check gas connections for leaks (gas heaters)
• Verify the T&P valve discharge pipe is properly positioned
• Test hot water at a faucet after the tank has heated
• Set the thermostat to 120 degrees F

When to Call a Professional

• Gas line modifications are needed
• Electrical panel upgrades are required
• Your local code requires a licensed plumber
• You are not comfortable with any step in the process

Summary

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