How To Keep Hot Tub From Freezing During Power Outage


Power outages can occur at any time, for any reason. The biggest concern is when it happens during snow storms which is usually followed by freezing temperatures. During that time, many people worry about the potential damage it can do to their hot tub since it can be a costly repair. So, how to keep hot tub from freezing during power outage?

In case of a power outage, you can adjust your spa to keep it warm for long time by doing the following:

  1. Cover the hot tub cover
  2. Get a hinge seal
  3. Place a small ceramic heater in the hot tub
  4. Check the water temperature every few hours
  5. Add hot water to the spa
  6. Use Hot Stones

Still, there are a few more things that you should be careful about. You will still need to check your hot tub every day and measure the water temperature.

Bonus reading

Are You Comfortable Winterizing Your Hot Tub?

Most people do this once a year so it is easy to miss important steps. For example, if you forget to check all the places where your hot tub system could hold some water that can turn into ice, that can break your hot tub and you will be surprised to not be able to start it in springtime. Follow this list to make sure you are not missing anything.

Will a Hot Tub Freeze Overnight 

If your home lost power while your hot tub was running, then you might be wondering if your hot tub could simply freeze overnight and sustain long-term damages because of that.

So, will your hot tub freeze overnight? Your hot tub cannot freeze overnight. On average, it would take more than 7 days before your hot tub can start freezing.

There are many things you can do in order to help your hot tub maintain the water temperature.

Can Other Hot Tub Parts Freeze Overnight

Your hot tub consists of multiple parts. Most of them get in touch with water. This means that each of them are at risk of freezing during power outages and extremely low temperatures.

So, can other hot tub parts freeze overnight? Other hot tub parts can freeze overnight. Typically, the most vulnerable spot for freezing is the equipment compartment due to being less insulated.

The reason for this is that the motors and equipment can breathe and run cooler. This is actually even more prevalent on a deck.

Keep in mind, it might be a little challenging to re-start with ice chips in the pump so make sure to look for that. People usually use a hairdryer to thaw things out.

How Long Will a Hot Tub Stay Warm Without Power

There have been many examples I found where people went 25 hours straight without power. In this particular instance, the night before the temperature dropped as low as 11 degrees, while the daytime temperature was in the 20s. 

They did not open the tub cover during the power outage.  After 9 hours of no power to hot tub, they put 3 layers of blankets on top of the hot tub cover and covered the whole tub with a plastic tarp.  

After 25 hours the hot tub water temperature had dropped from 102 to 97.

I was amazed that the hot tub water really suffered 5-degree loss in 25 hours through an 11-degree night. For sure, lots of factors can impact the outcome such as the wind, age of cover, a brand of the tub, but overall, there is no worry of having hot tub water freeze overnight.

Bonus reading

Is Your Hot Tub Costing You More Money Every Month Than You Thought It Would?

People read about other people spending only about $10 a month on their electricity bill for their hot tub and think that their $50 a month is too much. Well, that depends on a few important factors such as your geographic location and other. I did a research on how much people pay for their hot tub every month. You can read about my discovery here.

Do Not Do These Things To Your Hot Tub During a Power Outage

In case you find yourself in the situation of having no power with a hot tub running, make sure you do not do the following:

  1. Do not drain the spa
  2. Do not put flames under the hot tub
  3. Do not pour antifreeze into the spa
  4. Do not stuff blankets or comforters underneath the spa

Let’s look at each of these closely.

  1. Do not drain the spa! Most power outages in winter are resolved pretty quickly, and most hot tubs with any sort of insulation, and a good spa cover can hold heat for at least 24 hours. In case your spa was 90 F when the power went down, it could take a long time for temperatures in the equipment and pipes to cool to near freezing. This is especially true for a hot tub with a tight cabinet and good insulation.
  2. Do not put flames under the hot tub! Very often, the first thought one might have is to place a small fire, or a kerosene heater, or any gas heater under the spa. This can cause a big problem with melted spa parts, soot and carbon monoxide. Instead, keep the cover closed, and lay down heavy woolen blankets over the top if needed to prevent old spa covers from losing heat.
  3. Do not pour antifreeze into the spa. Another common issue people do. You might be laughing, but it is a true story. Don’t be fooled by the label that says “Non-toxic antifreeze for pools”, it’s definitely not safe to pour into the hot tub. Also, it wouldn’t work unless you put in an amount equal to at least 10% of your hot tub water volume.
  4. Do not stuff blankets or comforters underneath the spa. Once the equipment starts up, the heater and pump will need the air spaces to keep themselves cool. 

Good Things To Do During a Power Outage

In case you find yourself in the situation of having no power with a hot tub running, make sure you do the following:

  1. Cover the hot tub cover
  2. Get a hinge seal
  3. Place a small ceramic heater
  4. Check the water temperature every few hours
  5. Add hot water to the spa
  6. Use hot stones

Let’s look at each of these closely.

  1. Cover the hot tub cover with some heavy woolen blankets and even some plastic tarp. Wrap it tightly around the edges. This can prevent the heat from leaving, and it is especially recommended to do so with older covers or hot tub covers that don’t exactly fit the tub.
  2. Get a hinge seal; A hinge seal is an extra piece of foam and vinyl that is velcroed into the fold/hinge on the inside of the cover. Some covers might already have it. What is does is that it helps with heat loss coming out through the fold.
  3. Place a small ceramic heater or a 100W light bulb in the equipment area of your hot tub, in case you have a generator. Just make sure that the heater or bulb DOES NOT TOUCH any components or plumbing. 
  4. Check the water temperature every few hours using a floating thermometer that you can quickly access via a smartphone app, or by quickly lifting the cover just slightly. The water temperature in the pipes will need to reach a few degrees below 32° and stay there for several hours before they expand enough to cause some damage. At 32°, most of what will happen is that the water will just turn slushy and not freeze hard.
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  5. Add hot water to the spa. This is not a bad tactic and it’s cheap. What you need to do is to drain half the water, and refill with hot water from a garden hose connected to a spigot in the kitchen or your laundry room. 
  6. Use Hot Stones, that are warmed for 30 minutes in a fireplace or somewhere else like a wood-burning stove. What you want to do is to put them in a large iron skillet and have them placed under the hot tub cabinet. 8-10 large stones will do just enough to warm the cabinet spaces for the overnight.

What To Do In an Extended Power Outage (7+ Days)

If you think the spa won’t have power restored for more than 7 days, there are still actions you can take to keep everything safe and last longer.

You can drain your hot tub but only as a last resort in case there is a great risk of freezing and you have tried everything from above.

In general, hot tubs can be emptied for winter (called winterizing) but you have to do a very good job of it. One of the main challenges is getting all the water out of the plumbing (many will mistakenly only get out what they can see) and you should use RV antifreeze for what is left. 

What happens is that the water left in the plumbing freezes quickly. That will cause water to expand so the plumbing that is totally full of spa water will crack. 

My hot tub is not working after power outage

Hot tub winter power outage happens quite often, so unless you want to drain your hot tub, you need to prepare yourself for days without power going to your hot tub. Sometimes, it can happen that your hot tub doesn’t work after the power outage.

Here is a short list on how to check your hot tub after power outage.

  • The first thing to check is the electrical switchboard. Make sure that non of the switches are killed.
  • Once you can verify that you hot tub has the electricity, see if you can hear any buzzing or any other noises from your hot tub. I might indicate a pump issue.
  • Lastly, try resetting your hot tub. If that doesn’t work, then make sure to bring in professionals to inspect your hot tub and determine what’s wrong with it.

What to do if your hot tub freezes?

Don’t worry.

In case your hot tub is frozen, the first thing to do is to defrost your hot tub and get all the ice from the shell. You can do that by adding hot water or by placing a ceramic heater in the hot tub.

Finally, talk to your dealer so you know more about how to do it properly.

Editorial Staff

I'm Adnan Sabanovic, the guy behind Hot Tubs Report. I've had a chance to enjoy hot tubs last few years and have really become interested in owning one of them. Nearly every weekend you'll find me spending time with my family or playing sports. If I am not doing that then I'm here writing about tubs on Hot Tubs Report. This blog is a research for my first hot tub which I decided to document and share publically so others can benefit from it as well.

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