How to Winterize a Pool Heater

When the summer weather subsides, your pool water will quickly start to cool down. This is where your heater comes in! A good pool heater can extend your swimming season by a couple of months, which is a game changer, especially in regions with short summers. That said, even pool heaters will need to be put into hibernation eventually.

To keep your pool equipment running for multiple years and prevent it from breaking down in freezing temperatures, you’ll need to know how to winterize your heater. Let’s get straight into it!

Main Takeaways

• You need to winterize all types of pool heaters, including gas, electric, and solar.
• You should winterize your pool heater to prevent damage, extend the life of the heater, and save on energy costs.
• Winterize the pool heater once the temperatures start to consistently drop below 65°F.
• Other pool equipment to winterize includes pool heaters, return jets, pool lights, skimmers, etc.

Step-by-Step: How to Winterize a Pool Heater

Winterizing your swimming pool heater isn’t rocket science, but it is very important that you do everything correctly. Otherwise, you may break or damage your expensive heater. Here are the steps on how to winterize a pool heater.

Step One: Turn Gas Valves Off

With a gas heater, you’d need to turn off the valves completely. Usually, there are two: one on the heater itself and one on the gas line leading to the heater. Doing this is crucial to prevent gas build-up (and a possible explosion because of a stray spark).

Step Two: Turn Off Any Electrical Power

Whether you have an electric heater, a gas heater, or a heat pump, you’ll need to turn off the power. Unplug any power lines and switch off the circuit breaker switch leading to the heater.

Step Three: Turn Off The Pump and Filter

You will also need to turn off, disconnect, and winterize your pool pump, filter, and any other equipment attached to your plumbing. Check out my pool winterizing guide for more on this.

Step Four: Turn Off the Pressure Switch

Some gas pool heaters will have a pressure switch; most new ones will not, but if yours does, turn this off as well.

Step Five: Disconnect Your Plumbing and Drain the Heater

Next, you should disconnect the plumbing leading to your swimming pool heater. This allows the water inside the piping to drain and dry, which prevents it from bursting and expanding during the winter. 

Step Six: Open Winterization Ports

Most heaters will also have a drain plug to drain water inside the heater. Pull the drain plug and allow the water inside the heater to empty. There will generally be 2 to 4 standard threaded plastic or metal bolts. Be careful when loosening. Remove all of these plugs.

Step Seven: Blow Out the Heater

Once the heater is drained, use an air compressor/shop vacuum/leaf blower to blow out any remaining water. Once done, replace the plugs.

Step Eight: Cover the Heater

Cover the heater with a tarp or blanket to protect it from the elements. If you have a smaller heater that you can move, you could also store it inside a warm, dry shed. The bottom line is to keep the heater as dry and protected as possible during the freezing winter months.

Remember that all pool heaters are slightly different, so you’ll need to check your manufacturer’s instructions to ensure you do everything correctly.

What About Solar Heaters?

Solar heaters are generally a bit easier to winterize than gas or electric heaters. This is because many solar heaters are “self-draining,” meaning they do not retain water in the solar collectors. Self-draining solar heaters simply need to be turned off in the winter. And when they are turned off, all the water inside drains automatically, so they will be protected from cold temperatures.

If you don’t have a self-draining pool heater, you must drain the panels, turn on the isolation valves, and ensure no water is left inside the solar heater.

Pool Heater Winterization Tips

Here are a few additional tips for closing down your pool heater for the winter.

• Check your owner’s manual. People often forget that the design of pool heaters varies greatly depending on the model. More than likely, you will have winterization information specific to your heater model.
• Get started early. You don’t want to wait till the last minute to winterize the heater. The sooner, the better.
• Be careful. Remember, you’re working with gas or electricity. Do your research (reading manuals or guides like this article) before attempting any fiddling around with gas knobs by yourself.
• You won’t need any fancy equipment. Confused about the equipment you need? You will most likely not need anything more than a wrench (for the plugs) and an air compressor or leaf blower to blow out the heater. 
• When in doubt, call a pro. Not comfortable doing the winterizing of the pool heater yourself? Don’t worry! A professional pool contractor can easily close your entire pool for you, and winterizing the heater and other equipment is usually included in the price.
• Drain every last drop. Be thorough when draining all the water from the heater—even the smallest amount can freeze and damage your precious equipment.
• Keep your heater covered. You need to protect your pool heater from debris, snow, rain, and cold temperatures during the winter.

Why Should You Winterize a Pool Heater?

Not every pool owner needs to winterize their pool. But if you are winterizing your pool, you must also winterize your pool heater. Here is why.

Prevents Freezing Water From Damaging the Heater

Water expands when it freezes; this expansion can cause pipes and other components to burst and rupture. This can be very expensive to repair; in some cases, you may have to purchase an entirely new heater.

Extend the Life of the Heater

Stagnant, residual water can also cause rust and corrosion, dramatically shortening the lifespan of your heater. If you don’t prepare your pool and pool equipment for the winter, water, debris, and even animals trying to find warm shelter can damage your pool heater. Prepping it properly will protect it and extend its lifespan.

Saves Energy Costs

It may be tempting to keep your pool running throughout the winter by cranking your pool heater up and heating your pool water. Not only does this use a lot of resources, which is bad for the environment, but it is also insanely expensive. In fact, it can cost up to $600 per month to run a pool heater, and this cost could double when the outside temperature is especially cold. I highly recommend closing down and winterizing your pool in the coldest months rather than using your pool heater to warm the water. You probably won’t want to jump into your pool anyway!

Makes Opening Up Your Pool Easier

If you don’t close down your pool heater at all or winterize it too late, you may run into a whole host of problems when spring comes around. Winterizing all parts of your pool before winter ensures your equipment will function properly when it is time to reopen in the spring.

When Should You Winterize Your Pool Heater?

The answer to this question depends significantly on where you live. As a general rule of thumb, I recommend winterizing your pool once temperatures consistently drop below 65°F. This is considered a good time to start closing things up because algae does not survive at this temperature.

Obviously, with so many climate zones across the USA, the time your region drops below 65°F will vary. Here is a basic rundown of when to close your pool, depending on your season.

• Northeast: An area known for brutal winters and short summers—you might have to consider winterizing the heater around the end of September.
• Midwest: A region that experiences cold, harsh winters. Consider winterizing as early as late September or early October.
• Warm south: If you live in the warm southern states, you must know they’re famous for their mild winters. You could even skip doing so entirely, considering temperatures rarely drop below 65°F.
• Southeast: A relatively warm region of the USA that also experiences soft, mild winters. You might find it’s possible to wait till late October or early November to winterize the heater.

My advice is to keep an eye on the weather forecast for your area before winterizing your heater. In case of warnings of a sudden cold snap, you may need to close shop earlier than usual!

Check out my complete guide on when to close your pool for a more detailed run-through.

What Other Pool Equipment Should You Winterize?

Your pool heater is an important piece of equipment to winterize, but it isn’t the only one. Here is some other pool equipment that will need to be correctly closed down in the colder months of the year.

Pool Pump

Pool pumps are responsible for circulating water in the pool, so if you leave it running during the winter, the water inside them can freeze and ruin the motor. Don’t skip past this!

Filter

The filter helps remove all sorts of fine particulate matter (dirt, bacteria, debris, etc.) present in the water of the pool. Leaving it unwinterized or running during the winter can cause the filter to burst. Filters are EXPENSIVE, so you definitely want to be proactive on this.

Return Jets

Return jets “return” freshly filtered water back to your pool. You need to close and drain your return lines during the winter. You will need to use an air compressor to blow out all the return jet pipes before plugging them with rubber plugs.

Skimmer

The skimmer is one of the first lines of defense against larger debris in your pool. Winterizing your skimmer is pretty simple—you simply need to remove the basket, drain your pool water below the skimmer line, and let the components dry out before storing it somewhere safe.

Lights

Many pool owners don’t know they need to winterize the pool lights, but this is definitely something I suggest doing. You simply need to unscrew the bulbs and store them in a warm, dry place.

Frequently Asked Questions

Do I need to drain my pool heater in the winter?

Yes, you need to drain your pool heater in the winter. Skipping out on this step is risky since it leaves residual water in the pipes, which is dangerous and can cause damage.

Can I use antifreeze for my pool heater?

NEVER use automotive antifreeze in a swimming pool. It reacts dangerously with chlorine. In fact, do not use antifreeze on any of your pool equipment, including your heater. You can, however, use pool antifreeze, but unless your region gets blistering cold, this is likely not necessary.

Can pool heaters freeze during the winter?

Yes, they can! Pool heaters can freeze during the winter if not properly winterized. As the water in the heater freezes, you risk it expanding and damaging the equipment. This is why proper winterization is an absolute must!

Don’t Snooze on Winterizing Your Heater!

Your pool heater is one of the most important pieces of equipment. Without a heater, your pool season will be much shorter, and you won’t be able to control the temperature of the water. Show your pool heater your gratitude by taking good care of it and closing it down properly for the winter. Doing so will protect the heater and help it last for many more pool seasons.

If you have more questions on winterizing your pool heater, feel free to contact me! I am always happy to help.