Informational Guide

Can a Hot Water Heater Freeze?

by Andrew

While a hot water heater may be exactly what you need during the colder weather to keep yourself warm, the winter season could also cause your hot water heater to freeze.  

If you've always wanted to know the answer to 'can a hot water heater freeze,' we're here to help. In this guide, we'll provide you with everything you need to know to ensure that you keep your hot water heating in tip-top condition during the winter season.  

hot water heater can most definitely freeze, especially if it goes without power for an extended period of time or if it's placed in an outdoor location in frigid temperatures.

While it's uncommon for your hot water heater to freeze, especially because of how they’re designed, it’s definitely possible, especially if you’re not taking the necessary precautions.  

When the weather gets cold, the cold weather both freezes the water and expands the pipes in your hot water heater.

When that happens, your hot water heater will stop working. In some situations, however, if the pipe expands too much, it could burst and flood your home with water.  

outdoor water heater

Factors That Affect The Hot Water Heater Freezing 

Below are some factors that could affect the freezing of a hot water heater.  

  • Hot Water Heater Location (Basement Or Garage) 
    If your hot water heater is placed in the basement or garage, there’s a higher chance of it freezing, especially if not used regularly. The cold temperature would cause your pipes to expand and cause your hot water heater to stop working.  
  • Outside Temperatures  
    Sub-zero temperatures would mean that the pipes of your hot water heater are at a higher risk of expanding. Therefore, it's important that the pipes of your hot water heater are properly insulated during these frigid temperatures. 
  • Overly Exposed Pipes
    If your pipes are exposed, it means that it's more susceptible to wind chill and the cold weather. Overly exposed pipes are not only at a higher risk of expanding but there's also a high chance that the water within the pipes would freeze.  
  • Broken Or Cracked Pipes 
    When the weather gets too cold, pressure could potentially be placed on the pipes, and this could cause the pipes to crack or break entirely. When that happens, you won't have to just deal with icy water, but also a flood.  

What To Do If Your Hot Water Heater Freezes: Defrosting Tips 

If your hot water heater freezes, here's how to go about defrosting your water heater:  

  1. 1
    To start, you will want to check if it is the hot water heater that's frozen or it's the pipes. To do this, you can carefully touch your hot water heater to figure out which spot is cold. Once you’ve figured out that spot, go ahead and use a space heater or some other heating element to apply heat indirectly until that area thaws.  
  2. 2
    Check to see if there are any burst pipes. If there are, it’s important to locate the water shut-off valve before defrosting the pipes of your hot water heater. 
  3. 3
    If your whole hot water heater is frozen, you should disconnect your unit and take it somewhere safe, just in case it bursts as it thaws. 
  4. 4
    As your hot water heater starts to melt near somewhere warm, make sure that you're draining the water. To do so, shut the water supply to the heater off and open the small drain valve that's near the bottom of the tank. 
  5. 5
    Make sure that you’re allowing air to get in the tank. This can be done through a hot faucet or an air release valve on the unit. 
  6. 6
    Make sure that you check your unit carefully and ensure that there are no cracks or holes from the water expansion before connecting it back up. 

Winterizing The Water Heater (How To Prepare For Colder Climates) 

If you’re living in a colder climate, it’s important to protect your hot water heater and prevent it from freezing. Here’s how to go about doing so:  

ice cold snowflakes
  • 1
    Install your hot water heater away from the cold 
    If your tankless hot water heater is in a heated space, it’s less likely to deal with freezing issues. If that’s not possible, try to install it in an outdoor area that’s sheltered.  
  • 2
    Insulate both your hot water heater as well as the pipes 
    Insulate your pipes and hot water heater by wrapping them with heat tape, fiberglass, or polyethylene wrap.  
  • 3
    Take a look at a recirculation system 
    A recirculation system will make sure that your hot water heater is continuously pumping warm water into your home and keeping the pipes warm. 
  • 4
    Make sure that your hot water heater is constantly running 
    Try to make sure that your hot water heater is always connected to a power source. If your tankless hot water heater isn’t running, there’s a high chance of water freezing, expanding within the unit, and causing significant damage.  
  • 5
    Make sure you drain your water heater
    Standing water that collects inside your hot water heater can freeze and damage internal plastic components. This can be prevented by draining the unit.  

Will Your RV Water Heater Freeze In Winter? 

It is possible for an RV water heater to freeze in winter if it is filled with water and not running. If your RV water heater is frozen, you'll notice that you're not getting the same amount of water. You might also see icy residue over the body of the water heater and notice sounds like banging and clanging. Unfreezing your RV heater is similar to a standard hot water heater; you can use a portable heater to thaw your pipes or even use heat tape or a heat gun.  

To prevent such a situation from happening, you can winterize your RV heater or keep it running to maintain its temperature.  

tankless water heater on RV

People Also Ask (fAQs)

Should I turn off my hot water heater if my pipes are frozen? 

Yes, if your pipes are frozen, it is recommended to turn off your hot water heater along with your main water supply valve until repairs have been made. If not, you run the risk of damaging your hot water heater.  

At what temperature does hot water freeze instantly? 

It’s likely that hot water will freeze instantly in temperatures that are colder than -14 degrees. When this happens, it’s likely that the hot water will become a big white cloud that simply drifts away.  

How should I set my water heater in the winter? 

Set your hot water heater to about 120 degrees Fahrenheit to avoid any scalding or burning, especially if you have young children in your household. While there might be a temptation to turn the heat up during the winter, this could increase the risk of burns.  


As seen from the above, it’s more than possible for your hot water heater to freeze, especially if you’re not taking the necessary precautions. If your hot water heater does freeze, however, stay calm, assess the situation, and follow the steps accordingly.