What happens if the water heater is on but no hot water?

Author: Lucy O'Connell I  |  Last update: Thursday, July 17, 2025

A lack of hot water can be caused by a variety of issues. In electric water heaters, a power loss or heating element failure can cause water to no longer heat in the tank. In gas water heaters, a faulty gas connection, a bad pilot light, or a bad burner can cause no water to heat.

Why is my water heater running but no hot water?

Sediment Buildup

With time, sediment can build up in the bottom of the water heater tank. This buildup creates an obstruction between the heating element or burner and the water, causing inefficiency and could lead to no hot water. Sediment buildup is more frequent in homes with hard water, but it can occur anyplace.

What is the first thing to check when there is no hot water?

Check the circuit breaker.

If you have an electric water heater, the first thing to check when experiencing hot water issues is your circuit breaker. A tripped circuit means the current was disrupted. As a safety measure, the circuit breaker flips.

Why is my water heater lit but no hot water?

Sediment buildup is a common cause of a pilot light on but no hot water. A rusty thermocouple can also cause your water heater not to yield the right water temperatures. Another cause includes a tripped breaker or blown fuse. Contacting a plumber near you is the safest way to troubleshoot a faulty water heater.

How long can you go without hot water heater?

“No heating and hot water is considered as an emergency and thus should be resolved within 24 hours as an acceptable 'reasonable time'.”

No Hot Water: Water Heater Troubleshooting

How long can a water heater go without water?

In fact, most water heaters' heating elements will only last a few hours or even minutes without water. Operating a water heater without water leads to rapid overheating and damage to the heating element, significantly shortening its lifespan.

Can you shower with no water heater?

You should start by filling the bath with a few inches of cold water and then top it up with a kettle full of boiling water to take the edge off the cold. Of course, you could keep on boiling more kettles of water (or heat up water in pans) but the idea here isn't to fill the bath as you would normally.

Why have I suddenly got no hot water?

If you suddenly find yourself without hot water, it's worth checking your electrical panel to see if any fuses have blown or circuit breakers have been tripped. A blown fuse occurs when the system has an electricity overload, causing the fuse to melt and break the circuit.

Who to call if there is no hot water?

Well, it depends on the issue. But for the most part, you should call a licensed plumber for all hot water heater problems.

How to check if a hot water heater is working?

The easiest way to tell if your water heater is working is to open a faucet and see if you have hot water. Keep in mind that if you've just installed a brand new water heater, it will take some time for the tank to fill and heat up.

Who should I call if I don't have hot water?

If you can't tell where the source of the leak is, call a plumber to come and inspect the water heater or plumbing system. Also, check the thermostat and other compartments where leaking water can cause damage; if any component has water damage, it must be replaced.

Is it an emergency if you have no hot water?

Heating and hot water issues are often an emergency and need urgent attention. What is a reasonable time might change depending on the time of year. For example, a boiler repair is more serious during the winter.

What are the symptoms of a bad thermostat on a hot water heater?

Signs Your Water Heater Thermostat Is Faulty
  • You have no hot water.
  • You're running out of hot water quickly.
  • The water is too hot.
  • It takes a long time for your water heater to heat the water.
  • You keep having to reset the high-temperature limit switch.

How do you reset a hot water heater?

Somewhere on your electric water heater, you'll find a reset button. It's usually red and often located near the thermostat. It may also be hidden behind a removable metal panel on the unit—and then behind some insulation. Once you find the button, push and release it.

How long does it take for hot water to come back?

When you use up all of the hot water in a traditional water heater, you will often need to wait anywhere from 30 minutes to two hours or more for the water in the tank to reheat. This is why many people opt to switch to tankless water heaters.

Is no hot water a plumbing emergency?

In most cases, a lack of hot water is caused by problems with the water heater, a burst pipe, or an electrical issue. In some cases, your utility company is to blame. In any case, cold water coming from the hot water tap is a plumbing emergency that should be fixed ASAP to restore your home's hot water.

Why is my hot water heater not kicking on?

If the water heater stopped working completely, check the circuit breaker for electric heaters or the pilot light for gas heaters. Usually, the entire system stops when it loses power, which causes stress on the homeowner. Luckily, the fixes are easy to complete. For an electrical heater, restart the breaker.

What happens when no hot water comes out?

Check the Heater: If you have no hot water, the first step is to check the heater. If you have a gas-powered water heater, make sure that the gas valve is open and that there is enough gas supply. If you have an electric water heater, make sure that the breaker is not tripped.

How to fix water not getting hot?

6 Things to do When Your House Has no Hot Water
  1. Check the thermostat settings. Many manufactures set the thermostat to 140 degrees Fahrenheit by default. ...
  2. Check the circuit breaker. ...
  3. Check the pilot light. ...
  4. Check for leaks. ...
  5. Flush the tank. ...
  6. If all else fails: Upgrade your hot water heater.

How long do hot water heaters last?

While today's water heaters are better designed than older models, they still require regular maintenance in order to prolong their lives. With regular inspection, draining, and flushing, you can expect a gas water heater to last anywhere from 8-12 years and an electric water heater to last anywhere from 10-15 years.

What happens when a hot water heater goes out?

If your hot water heater “goes” – meaning the plumbing or the unit fails in some way – it will continue to pump water into your living space until it is discovered and the main water supply valve is shut off.

What should you never do with a hot water heater?

DON'T set your water heater temperature above 120 degrees Fahrenheit. DON'T keep combustible material within 18 inches of the hot water heater. DON'T leave children unattended around a hot water heater. DON'T allow plaque and sediment to build up in your tank.

How to temporarily get hot water?

Portable water boilers can also be used for emergencies when your normal boiler goes down. Portable boilers are suitable for temporary heating projects, hot water supply, underfloor heating and curing screed floors.

What happens if you run a hot water heater with no water?

That leads to “dry firing,” where the heating element burns out, or worse, damages the tank itself. For gas water heaters, running with no water means pressure can build up, and no one wants that—pressure can lead to leaks or cracks.

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