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How To Turn On a Water Heater: The Correct Way

Learn how to turn on a water heater the correct way.

Your water heater sits day and night delivering all the hot water you need, but sometimes it needs to be switched off for maintenance and repair. Knowing how to turn on a water heater safely is crucial for any homeowner.

We show you how to start a water heater, covering the different types of heater available in easy-to-follow instructions.

Key Takeaways

  • Check all valves and faucets are closed before turning on a water heater.
  • For gas water heaters, turn on the cold water, light the pilot light, and then turn on the gas valve.
  • For electric water heaters, ensure the breaker is off, fill the tank with cold water, and then turn on the breaker.
  • For tankless water heaters, simply turn on the breaker and set the desired temperature.

How To Turn On a Gas Water Heater

gas water heater

In the US, around 50 percent of homes use natural gas water heaters. However, some gas water heaters use propane or other canister gas, especially in remote areas far from the natural gas supply.

That said, the principle of lighting a gas water heater is the same.

1. Check All Valves and Faucets Are Closed

Take a tour of your home, keeping a careful watch for open faucets. You may have opened them when making repairs to the heating and needed to drain water from the system.

Also, check all the valves, on the water heater and any other pipework around the home. Make sure they are all closed.

2. Turn On the Cold Water

The tank is empty, so before lighting the heater, it needs to be refilled. Locate the water shut-off valve and turn it on and wait while the tank fills.

3. Light the Pilot Light

It’s now time to ignite the pilot light. Some water heaters have a red or black ignition button, while others require a naked flame to light. When the pilot ignites, continue to hold down the button for 60 seconds before releasing it.

If the pilot light fails to light, you may need to press down the spark generator every 10 seconds until it fires up. You can see the flame through a small window in the water heater.

If you have the manual style pilot light, use a long-reach lighter to ignite the flame. Turn the gas valve to “pilot,” and hold the knob down while you light it.

Hold it down for 60 seconds once the flame ignites and then release it. You should hear a woosh or a clicking sound, indicating that the boiler is on.

4. Turn On the Gas Valve

If the gas valve is already set on “Pilot” you don’t need to go through the pilot lighting exercise, and all you need to do is turn on the gas valve and wait while your water tank heats.

How To Turn On An Electric Water Heater

Electric water heater

A third of US homes have electric water heaters. They are more efficient than gas varieties and are considered greener because they don’t burn gas.

Here’s how to switch on an electric heater.

1. Check the Breaker

Before switching on the water heater, check that the breaker that controls the unit is switched off.

2. Check All Valves and Faucets Are Closed

Just as you did before lighting the gas water heater, you need to check that all the faucets are closed, and all the valves are in the off position.

3. Turn On the Cold Water

Make sure the tank is filled before switching on the heater. Turn on the water at the valve and wait about an hour while the tank fills.

4. Remove the Safety Tag

If you placed a safety tag on your breaker to stop anyone from switching it on, it’s time to remove it. This is an extra safety precaution that could save you from getting an electric shock.

5. Turn On the Breaker

Turn the breaker on and wait while your water heater begins to heat the water in the tank. With some electric water heaters, it’s not as obvious as gas-powered varieties that they have started working because they are silent. You don’t get the same woosh sound that you get on a gas water heater.

How To Turn On a Tankless Water Heater

tankless water heater

Thankfully, tankless heaters are the easiest to switch on. Surprisingly, they aren’t as popular in the US as they are in Europe and the UK. It may have something to do with the expensive price tag.

1. Turn On the Breaker

There is no tank with this heater, so you don’t have to wait while the tank fills and heats up. Simply switch the breaker from off to on.

2. Set the Temperature

This type of boiler is an on-demand heater, so you get to set the desired temperature, and it won’t kick in until you turn on the faucet. The initial temperature of the water coming out of the tap is cold, but it starts to heat up to the chosen temperature but after a few seconds.

These heaters are considered less wasteful because you only heat the water you use rather than a large tank.

Safety Considerations

When you are dealing with water heaters, there are always dangers, so taking safe steps to protect yourself is a sensible approach. So, what should you look for before switching on your water heater?

Check the Discharge Pipe

If you notice water coming out of your discharge pipe, you could have too much pressure in the system. Adjust the settings the moment you see drips. Below 80 PSI (pounds per square inch) is low enough.

Use Your Nose

Natural gas is odorless, but that acrid smell you recognize is an additive for safety reasons. If gas didn’t smell, how would you know you have a leak? If your water heater hasn’t been fired for a while, try to smell for gas escaping when you turn it on.

If you detect any bad smells, don’t light the pilot light until you have investigated the source thoroughly. If you have a modern water heater, it probably has a fail-safe switch that won’t allow you to light it if there is a gas leak.

Pilot Light Goes Out

If the pilot light goes out, check for the source of the problem before relighting. It could be something simple like dirt between the element causing a blockage. If you can get access to the pilot light before lighting, give it a quick blow clean with your mouth.

Get Your Heater Serviced

It’s better to be safe than sorry, so to avoid dangerous situations occurring, get your water heater serviced annually. It gives you the peace of mind that you are not sitting on a ticking time bomb inside your home.

Keep Your Distance

Whenever you are dealing with naked flames, it’s always better to keep your distance. Never put your face near the pilot light once it is lit.

The Pilot Light Won’t Ignite

If the pilot light doesn’t catch, it could be a blockage, which is easy to sort. If you have cleaned the pilot and it still won’t light, it could be a sign of something more serious. If you suspect anything, call in the professionals.

Follow the Instructions

Your water heater came with detailed instructions to help you troubleshoot. It’s always a great idea to have those instructions handy and read them. You should also see instructions on how to light the pilot light plastered to the front of the water heater to make it easier to understand.


How Do I Know If My Electric Water Heater Is On?

It’s a lot easier spotting that your gas water heater is lit compared to your electric model. When the heater lights, it makes a clicking sound or a woosh, like it is firing up. Electric water heaters are pretty silent, so look for an indicator light and feel the side of the water tank to feel if the water is heating.

What Do I Do If My Water Heater Won’t Light?

It could be the pilot light causing the issue. Sometimes they get dirt and blockages, so it’s always a great idea to keep them clean during servicing intervals. If you have cleaned the pilot light and it still won’t fire up, it may be time to admit defeat and call in the experts.

Do All Water Heaters Have a Reset Button?

All water heaters have a reset button; you just need to find it. It is typically red or another bright color and is usually located near the thermostat. It is also possible that it is hidden behind a detachable panel.

How Do I Reset My Hot Water Heater?

Isolate the electrical supply by switching off the breaker, and then locate the reset switch. Press it, and the heater should be reset. Now turn the power back on.

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About the Author

Mark Weir

Mark spent 24 years working in real estate, so he knows his way around a home. He also worked with contractors and experts, advising them on issues of planning, investments, and renovations. Mark is no stranger to hands-on experience, having renovated his own home and many properties for resale. He likes nothing better than seeing a project through to completion.