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How to Turn On a Water Heater – Guide for Every Water Heater

Fact checked by Stephen Conklin

how to turn on a water heater

No one likes taking cold showers at the start of the early morning. But when moving into a brand new home, your faucets will be flowing with cold water unless you turn the hot water on since your brand new water heater is still off.

Homes come with different types of water heaters, and it might be confusing to figure out how to start a hot water heater. But, worry not since whether your heater is a gas water heater, an electric water heater, or a tankless water heater, we will walk you through the step-by-step on how to turn on a water heater.

Below are detailed steps on how to turn on hot water heater; follow the guide below after finding out which type of water heater you own.

Table of Contents

Make Sure Your Water Tank Is Already Full


The first thing you should try is checking to see if your tank has properly filled up. To do so, simply follow the process below. Prepare a long hose to drain your water tank.

Turn off the water supply and shut-off valve (gas water heater) or the circuit creaker (electric water heater)

The valve for your cold water supply is usually located on the top of most water heaters. By switching this valve off, water will cease to go through your pipes, allowing you to work without worrying.

  • Suppose you have a gas water heater to prevent gas from leaking and potentially causing accidents, locate the gas shut-off valve and tightly turn it to cut the gas supply. In that case, this will prevent any gas from flowing into the water heater.
  • To prevent shocks, especially with electric water heaters, it is best to turn the water heater breaker off. If you can’t find the one assigned for your water heater, you may also opt to turn the main circuit off. Doing so will cut all power.

Drain the Tank

Locate the spigot located on the bottom of most water heaters and attach a hose to it. Open the drain valve and allow the water in your tank to flow out for roughly 5-10 minutes.

While keeping the drain valve open, turn on your cold water supply valve to help clean the inside of your tank. Do this for another 5-10 minutes.

A steady stream of water should indicate that all the residue inside your tank has been successfully flushed out.

Close the Drain, Open the Supply

When your tank is now all clean, shut off the drainage valve and leave your cold water supply valve open and wait until your tank fills itself up.

Check the hot water taps

Constantly check the nearby faucets, turning them on so that the air would escape as the tank fills itself up; opening the nearby hot water tap allows the pressure inside the tank to remain constant and prevent unwanted accidents from happening.

Once you notice that the water stops sputtering and has a steady stream, your water tank is now full.

Turn the supply valve (gas water heater) or the circuit breaker (electric water heater)

After confirming that your tank is full, you’re ready to turn your heater back on.

  • For gas water heaters, you’d want to switch it to “on” so you can now light up your pilot light.
  • For electric heaters, on the other hand, you’d want to turn the circuit back on to restore power.

Turning on a Modern Gas Water Heater

Follow these basic steps in order to turn on a gas water heater:

Step 1: Turn the Temperature Down and Switch it Off

Before you begin to turn on your hot water heater, you first have to turn it to a suitable temperature, preferably the lowest setting. Locate the control switch and turn it to the “pilot” setting.

Step 2: Start The Pilot Light

To do so, you have to press the pilot igniter button down while simultaneously pressing down on the spark generator. Doing this would create a spark that helps light the pilot light, which you may observe through a tiny transparent window located on your tank.

Step 3: Hold It!

When you see the spark, please continue to hold your pilot igniter button down for about 30 seconds to make sure that it would produce enough heat when released. If the light does not stay lit, you can also press down on the spark generator button every 10 seconds until it properly lights up.

Step 4: Adjust the Temperature and Turn it On

When it has properly lit up, switch the control to “on.” Afterward, you can now adjust the temperature to your desired range. You can double-check if there is a small flame noticeable through the tiny glass window.

Turning on an Older Gas Water Heater


The difference between the older and the newer versions of a gas water heater isn’t that far off, and both share most of the steps. Read on to see the things you should do differently if your water heater is the older version.

Use a long-neck/candle lighter for this tutorial.

Step 1: Lower the temperature and change the setting to ‘Pilot’ mode.

Before lighting your old water heater on, you first have to turn the temperature dial to its lowest temperature for safety measures.

You would then find the regulation valve located at the top of your heater and then twist the valve to “off,” this is essential before turning your gas on. After waiting 10 minutes, you may now turn the regulation valve to “pilot.”

Step 2: Remove the Access Panel

Most hot water heaters would come with an access panel, an inside panel that insulates, and an outer panel or protectio that covers the pilot light. Removing these will make pilot light access much easier.

Step 3: Hold the Pilot Button

Locate the pilot button; it is usually in the form of a black or red button. Once found, press and hold the button; this would help you in starting your pilot light.

Step 4: Light up the Pilot Light

To start turning your water heater pilot light on, look for the silver pilot supply tube, which is usually connected to the gas control valve. Use a long-necked lighter for your safety.

Step 5: Press Pilot Light Button

Once you’ve lit the pilot light, continue to press and hold the pilot button for around 30 seconds and slowly release it until you’re sure that it will remain lit if it goes out again; press and hold the button for longer than 30 seconds.

Step 6: Place the Access Panel Back

Remember to always place the access panes back since forgetting to do so will fan the open flames into the surroundings and cause unwanted accidents.

Step 7: Turn On and Adjust Temperature

Switch the control back to “On” and turn it up to the temperature that you’re comfortable with. Your heater will start heating the hot water, for up to 30 minutes. Check any open faucets nearby to confirm temperature constantly.

How to Turn on Electric Hot Water Heater or Tankless Water Heater

The following are the steps in order to turn on your electric or tankless water heater:

Step 1: Switch the breaker on

To turn on your electric water heater, you first have to locate the breaker that controls your electric water heater and flip the switch to the “on” side.

If your circuit breaker is unlabeled, you must first check your water tank to see the amp rating. It is usually written or labeled in your water tank. Once you have found this, find the breaker switch with the amp rating that matches your water tank.

Step 2: Sit and wait

Once your tank has been switched on, you need to wait since it takes a couple of hours to heat up completely. You can open faucets nearby to check the temperature of your water constantly.

Step 3: Turn off the gas

Before turning on your tankless heater, you first have to turn off the gas. Once you’ve turned it off, locate the circuit breaker or switch that provides the power to the tank and turn it on.

Step 4: Check temperature

Adjust the temperature settings usually found on a digital controller. Once you’ve turned it on, open any taps nearby to check on the temperature of the water constantly.

Step 5: Turn gas on

Once you’ve set your desired temperature, all you have to do is turn the gas back on. Tankless water heaters often heat on demand, so they would start heating the water only when in use.


Turning on the water heater isn’t all that hard, and we hope that by reading through and by following our comprehensive post, you’re able to enjoy the hot water flowing through your taps fully. These tips are valuable not only for new homes but also for secondhand homes if the previous homeowners decided to switch the water heater off when they left.

We hope that you found this post helpful, and we would love to hear from you. Please do share and comment on this post on your experience with how to turn on a water heater.

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