There is nothing quite as shocking as jumping into a shower only to be hit by a blast of freezing water. Whether you are returning from a vacation, moving into a new home, or just finished a repair, knowing how to turn on a water heater safely is a homeowner essential.
While the process varies depending on whether you have a gas, electric, or tankless model, the goal is the same: getting hot water flowing without damaging the unit. We will walk you through the specific steps for each type so you can ditch the cold showers and get comfortable again.
Key Takeaways
- Fill the tank first: Always ensure the tank is full and air is bled from the lines before turning on gas or electricity to prevent damage.
- Gas heaters: Open the gas valve, set the knob to “Pilot,” light it (using the piezo igniter or a match), and then turn the dial to the desired temperature.
- Electric heaters: Shut off the breaker, fill the tank until water flows from a hot tap, and only then flip the breaker switch on.
- Tankless heaters: Verify water and gas/power supplies are open, turn the unit on, and set your digital temperature.
How to Turn On a Gas Water Heater
About half of US homes rely on natural gas water heaters. While some older models or units in remote areas might use propane, the lighting process is almost identical.
Modern gas heaters usually have a built-in spark generator (piezo igniter), while older models require you to manually light the pilot with a match. Here is how to get the flame going.
1. Inspect for Gas Smells
Safety comes first. Before you do anything, smell the area around the heater. Natural gas and propane have an additive that smells like rotten eggs. If you smell gas, do not light the heater. Leave the house immediately and call your utility company.
2. Fill the Tank
Never light a water heater that is empty. Locate the cold water shut-off valve above the unit and turn it parallel to the pipe (open).
3. Bleed the Air Lines
This is a critical step. Go to a bathroom or kitchen sink and turn on the hot water faucet. You will hear sputtering and hissing as air escapes. Leave the faucet open until a steady stream of water flows out. This confirms the tank is full. You can then close the faucet.
4. Open the Gas Valve
Locate the gas line feeding into the thermostat control box. Turn the handle so it is parallel with the pipe. This allows gas to flow to the unit.
5. Light the Pilot Light
Locate the control knob on the front of the thermostat.
- For Piezo Igniters (Red/Black Button): Turn the control knob to “Pilot.” Press and hold the knob down. While holding it, press the ignition button repeatedly until you see the small blue flame ignite through the sight glass. Keep holding the control knob down for about 60 seconds to warm the thermocouple.
- For Manual Lighting: If you do not have a clicker button, you will need a long lighter. Turn the knob to “Pilot” and hold it down. Apply the flame to the pilot tube nozzle inside the access panel. Once lit, keep holding the knob for a minute.
6. Set the Temperature
Release the control knob. The pilot light should stay lit. Turn the knob from “Pilot” to “On” or your desired temperature setting (usually around 120°F). You should hear a “whoosh” sound as the main burner ignites.
How to Turn On an Electric Water Heater
Electric water heaters are popular for their efficiency and simplicity. However, they are also the easiest to break if you skip the “bleeding” step. An electric heating element that turns on in an empty tank will burn out in seconds (known as “dry firing”).
Follow these steps carefully to avoid a repair bill.
1. Ensure the Breaker is Off
Go to your electrical panel and verify the circuit breaker for the water heater is in the OFF position. Never fill the tank while the power is on.
2. Open the Cold Water Valve
Turn the cold water inlet valve to the open position to let water rush into the tank.
3. Run a Hot Water Faucet (Essential)
Go to a sink or tub in your house and turn on the hot water handle. Initially, air will push out. Wait until the water runs clear and steady without any air bursts. This guarantees the tank is completely full of water and safe to power up.
4. Turn On the Circuit Breaker
Head back to your electrical panel. Flip the breaker switch to the ON position. Unlike gas heaters, electric models are silent. You won’t hear a burner kick on, but the heating elements are now working.
How to Turn On a Tankless Water Heater
Tankless heaters are technically the easiest to start because they don’t store water. However, the procedure differs slightly depending on if you have a gas or electric model.
1. Check Utilities
- Electric Tankless: Ensure the circuit breakers (you may have more than one) are on.
- Gas Tankless: Ensure the gas supply valve is open and the unit is plugged into an electrical outlet (for the digital display and igniter).
2. Open Water Valves
Ensure both the incoming cold water valve and the outgoing hot water valve on the unit are fully open.
3. Power On and Set Temperature
Press the power button on the control panel. Use the arrow keys to set your desired temperature (120°F is standard). The unit will sit idle until you open a faucet; at that point, it will instantly fire up to heat the water on demand.
Vital Safety Checks Before You Start
Water heaters involve high pressure, electricity, and combustible gas. A few quick checks can prevent dangerous malfunctions.
Inspect the T&P Relief Valve
Look for the Temperature and Pressure (T&P) relief valve, usually located on the side or top of the tank with a discharge pipe running down. If this pipe is dripping before you even start, you may have a faulty valve or high pressure. Keep an eye on it as the water heats up.
Clear the Area
Water heaters need air to breathe, especially gas models. Ensure the area around the base of the heater is free of combustible items like boxes, paint cans, or rags. Blocking the air intake can create a fire hazard or carbon monoxide buildup.
Check for Water Leaks
Before leaving the unit to do its job, inspect the plumbing connections on top of the tank. If you see any water dripping, tighten the fittings gently or call a plumber. A small leak now can turn into a flooded basement later.
Wait for Hot Water
Recovery time depends on your energy source. Gas heaters typically heat a full tank in 30 to 40 minutes. Electric models are slower and can take 60 to 80 minutes to fully recover. Be patient and check the water temperature at a faucet after an hour.
FAQs
How Do I Know if My Electric Water Heater Is On?
Because electric heaters are silent, you cannot hear them running. The only way to confirm it is working is to wait 45 to 60 minutes and check a faucet for hot water. If you have an electric meter, you can also watch to see if the spinning disc or digital usage spikes when you flip the breaker.
What Do I Do if My Water Heater Won’t Light?
If the pilot won’t stay lit, the thermocouple is likely dirty or faulty. Try holding the pilot knob down for a longer period (up to 90 seconds) before releasing. If it still goes out, ensure the gas valve is fully open. If these steps fail, you likely need a professional to replace the thermocouple.
Do All Water Heaters Have a Reset Button?
Most electric water heaters have a red reset button located on the upper thermostat. You will need to remove the metal access panel (and move some insulation) to find it. Gas water heaters generally do not have a red reset button; they rely on the thermocouple safety switch instead.
How Do I Reset My Hot Water Heater?
For an electric heater, turn off the breaker first. Remove the upper access panel and insulation. Press the red button firmly until it clicks. Replace the cover and turn the power back on. If it trips again immediately, you have an electrical short or a bad thermostat.
How Long After Turning on Water Heater Can I Shower?
It depends on the size and type of your heater. A gas water heater usually provides enough hot water for a shower within 30 to 45 minutes. An electric water heater generally takes about an hour to heat the full tank. Tankless heaters provide hot water instantly.
