What do you do when you water heater decides to go “kaput?” What makes it worse is that it can happen in the middle of the night or when in the midst of the coldest winter ever! The best thing you can do is replace the water heater. But is replacing a water heater an easy job? If you follow this guide, you’ll find that replacing your old and broken water heater can be replaced without much trouble. While you always have the option of getting your water heater replaced by a plumber, if you are in the DIY mode or if you can’t afford to pay the professional, then this guide will help you get the job done.

Step-By-Step Guide To Replacing A Water Heater

Select A New Water Heater: Choosing one similar to the type that’s gone kaput will help in installation. So if you had an electric water heater, it’s best to replace that with a new electric water heater and same with gas. The size doesn’t make that much of a difference; for ex: you can choose a 50 gallon over the old 40 gallon one and still be fine.

Getting The Tools & Fittings Together:


1.    Hacksaw/ pipe cutter
2.    Wrenches
3.    Screwdrivers
4.    Adjustable open-end wrench
5.    Drill + 1/8 inch bit
6.    Soldering torch
7.    Appliance cart / hand truck


1.    Water heater
2.    T&P relief valve
3.    Vent pipe fitting
4.    Gate valve
5.    Flexible connectors for water and/or gas
6.    1/2 -inch flare adaptor
7.    Teflon plumber tape
8.    Pipe dope
9.    Hose
10.    240-volt neon test light
11.    Hand cleaner

1)   Check The Existing Plumbing: Having assembled your tools and fittings, it’s time to check the plumbing. So assuming that you are replacing a water heater with a new one of the same dimensions and fuel-type, check the conditions of the various pipes – hot and cold; check the gas union for a gas fuelled water heater; ensure shutoff valve is closed for cold water inlet as is the hot water outlet.

2)   Setting Up The New Heater: Once the new water heater if offloaded from the truck and put at the site of installation, you are ready to start installing the new appliance.

3)   Turn Off Electricity, Water, and/or Gas Supply to Water Heater: Before you start the new installation, you need to turn off the utilities for the old water heater.

4)   Turn off the shut off valve
•    Shut down the electricity supply for your electric water heater by turning off the breaker
•    For gas water heaters, cut the gas at the supply pipe or simply shut off the gas supply to your home. Double check by making sure the pilot light is off.

5)    Drain Out All The Hot Water In The Tank: If you are replacing a water heater with a tank, you need to drain out all the water in the tank. Check our DRAIN HOT WATER article on how to do this.

6)   Cut Off Utility Lines: Cut off hot, cold water supply to the water heater. Also cut off gas or power supply to the heater.
•    Using the pipe wrench, remove the plumbing.
•    Disengage the flue from the old water heater. Disconnecting flue ensures water lines and fuel line has been disengaged and you can now remove the old appliance.

7)   Remove The Old Heating Unit.
•    Clean the floor and walls at the site of the old installation.
•    Take help of an assistant and move the new unit into position.
•    Carefully adjust the unit so that the existing plumbing points are aligned with the unit’s points.
•    Ensure all joints are in a single line and your new heater is straight from top to bottom.

8)    Install The New Water Heater Fittings: Now it’s time to install the fittings. We hope so far you are with us in replacing a water heater.
•    Start by installing the T&P relief valves.
•    Next is the discharge drain pipe.
•    Stick some Teflon tape in copper parts and pipe dope on the galvanized fittings.
•    Install the remaining fittings, if any, according to the instructions in the manual.

9)    Engage the water pipes
•    Connect hot with hot and cold with cold outlet and inlet respectively.
•    Use flexible copper lines if the outlet and inlet points don’t line up.
•    Screw in the shut off valve to the cold water supply point.

10)    Engage the gas or electric line: Having connected the water pipes it’s time to connect the fuel line.
•    For gas heaters, connect the gas line to the control valve of the gas burner.
•    Check for leaks or lose fitting by turning on the gas supply and smearing the gas union and all other joints with soap water solution. If bubbles are visible, tighten the connections. If you can seal the leaks, call your plumber for help.
•    For electric heaters, connect the electric lines and supply wire to the junction box.

11)   Attach Flue: If you have a gas water heater, attach the (exhaust) flue.
•    Next, connect the draft diverter above the flue.

12)   Turn On: Now that all connections are in place, it’s time to turn on the device.
•    Start by allowing cold water to fill up inside the tank and then turn on the water heater.
•    Replacing a water heater can be fun, and we hope so far you have enjoyed the process.
•    In order for cold water to fill inside the tank, turn on your main water supply valve as well as the cold water supply valve to the heater.
•    Close the hot water tap, which you had opened to drain the tank.

13)   Check that the tank is full by opening the hot water tap in your kitchen. If water flows out, the tank is full. However, the flowing water will be cold.
•    Now that you are sure that the storage tank is full of cold water, turn on the gas or the electricity for resetting the breaker or by opening the main gas valve and make sure the pilot light is on.

14)   Set the temperature on the thermostat to 110 to 130 degrees and allow the heater to do its thing.

15)   After sometime check for hot water by turning on the hot water faucet in your kitchen.

16)   Congrats! You have just learned about replacing a water heater gone bad with a brand new one!

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