How to Heat a Pool: Your Options

One major issue pool owners have to deal with in the colder months is water temperature. Cold weather can bring down your pool water temperature and make it unbearable to swim in. Fortunately, technology is available that allows you to heat your pool water, thereby extending your swimming season.

In this article, I will go over some popular methods for heating up your pool and discuss the pros and cons of each one. I will also answer some frequently asked questions.


Main Takeaways

  • Gas heaters are the fastest option to heat up your pool, but they have high ongoing costs and are not eco-friendly.
  • Heat pumps cost more initially, but they are more eco-friendly and cheaper to run.
  • Solar pool covers are a great way to maintain your pool temperature.
  • Solar domes are an economical and eco-friendly option for smaller pools.

Natural Gas or Propane Pool Heater

One of the more efficient ways to heat a pool is by using a propane or natural gas heater. A gas pool heater warms the pool water as the water is pumped through the filter. It is not the most energy-efficient method because you will burn natural gas as you heat the pool, but it is the fastest way to heat it. Gas heaters can also operate in colder temperatures better than most other heating methods.

How Fast It Heats The Pool

The amount of time it will take to heat your pool using a gas heater depends on several factors, including:

  • Capacity of your swimming pool
  • Outside air temperature
  • Size of your heater

Since gas heaters can generate a decent amount of heat in cold temperatures and use natural gas to heat the water, they are the fastest option for pool heating. You can expect a gas heater with the specs to fit your pool to heat your water up about 20 degrees in about 8-12 hours. Small pools or spas can take as little as 2-5 hours to heat the pool.

20 degrees can be a game-changer, meaning you’ll be able to utilize your pool throughout the fall season and maybe even at the beginning of winter. But keep in mind these heaters come at a cost.

Estimated Cost

Why doesn’t everyone use them if gas heaters do such an excellent job at heating swimming pools fast? The answer comes down to the cost. Using gas heaters constantly will increase your energy bill exponentially. Depending on your region, natural gas can be one of the more expensive utilities, so running it for hours at a time will lead to a hefty bill.

In the USA, the estimated cost for using a gas heater is $3-$7 per hour, depending on the size of your heater and the cost of natural gas in your state. This may not seem like a lot, but considering it will take up to 12 hours to heat your pool 20 degrees, it may cost you up to $84 to fully heat your pool one time.

When it comes to initial costs, you should expect to pay between $1,500 and $5,000, depending on the size of the heater required. You can read my analysis on the average pool heater cost for more information.

Pros

  • Can heat your pool up to 20 degrees in 10-12 hours
  • Is able to heat the water at colder temperatures
  • Simple to use and relatively inexpensive to get installed
  • They are generally reasonably cheap to install

Cons

  • Gas can be a more costly energy source, making gas heaters expensive in the long term.
  • You will not likely be able to install a gas heater DIY due to the complex components. Unlike other heating options, you will have to hire a professional for the installation process.

Electric Heat Pump

Electric pool heaters are another popular option for heating your water. Most heat pumps use hot air to warm the cold water that flows through them. This process will eventually warm the pool water. Since electricity is usually much cheaper than gas or propane, heat pumps are cheaper to run than gas heaters. But they do take a bit longer to heat up the pool, and they will not function efficiently at colder temperatures.

How Fast It Heats The Pool

In comparison to gas heaters, electric heat pumps are much slower at heating up pools. You can expect a standard heat pump to warm the water by 20 degrees in about 12 hours for smaller swimming pools. For larger swimming pools, expect at least 24-48 hours.

It is worth mentioning that most heat pumps will not function if the outside air temperature is below 50 degrees. The only way to bypass this issue is to purchase a water-sourced pool heater, which draws heat from water rather than the air.

Estimated Cost

Electric heat pumps will cost you less over time than gas heaters due to energy costs, but they are a more expensive initial purchase. A basic heat pump for a smaller pool will set you back up around $2,000, but it can cost up to $8,000 for larger pools.

It is hard to precisely estimate ongoing costs because energy costs vary from region to region, but electric heaters will cost you anywhere from $30-$200 a month to operate, making them much more affordable than gas heaters.

Pros

  • Is usually more eco-friendly than gas heaters
  • Cheaper to run in the long term
  • Will extend your swimming season for over a month

Cons

  • Costs more for the initial set up
  • Will not function at temperatures lower than 50 degrees
  • Much slower at heating water than gas heaters

Solar Pool Cover

Solar pool covers function more like insulators than heaters, but they can still warm the water slowly. They are essentially a blanket that you put over your pool when it is not in use that prevents heat from escaping the water. Using these covers can extend your pool season and keep the water at a constant temperature.

How Fast It Heats The Pool

Solar pool covers should not be used as pool heaters, but more as insulators. They are not the most reliable for warming your pool water because they require lots of sunlight. I recommend using a solar blanket with another heating source to cut down energy costs.

Solar Blankets

Solar blankets can warm your water by 10-15 degrees throughout the day and are very effective (90-95%) at trapping the heat in the water.

Liquid Solar Covers

Liquid solar covers are not very effective at raising the temperature of your pool water, but they are a great affordable way to trap the heat in your water. On sunny days, they can maintain 75 percent of your pool temperature.

Solar Rings

Solar rings are best used during the warmer months to prevent evaporation and heat loss. They are 60-80 percent effective at maintaining your water temperature.

Estimated Cost

The best thing about solar pool covers is that they do not require any ongoing costs. Since they use the sun’s energy to warm the water, there won’t be an energy bill.

Here is a breakdown of the estimated cost for each type of solar cover:

  • Solar blanket: $200-$400
  • Solar rings: $150-$300
  • Liquid solar cover: $20-$30 per bottle

Pros

  • Low initial cost
  • Essentially zero ongoing costs; free to run
  • Eco-friendly
  • If used with another heating source, you can insulate your pool and prevent heat from escaping the water

Cons

  • Not a viable option for extending your swimming season
  • Not suitable for all sizes of pools
  • Does not actually heat the pool water by much

Solar Dome

Solar domes are energy mechanisms that use energy from the sun to heat up water pumped through them. Although they are not very effective on large pools, they are great options for smaller pools and above ground pools. You can check out my recommendations for the best solar pool heaters for some top options, and my guide on how to heat an above ground pool.

How Fast It Heats The Pool

Depending on the size of the solar dome you purchase and the capacity of your pool, it can take anywhere from 1-3 days to heat up a swimming pool by 10 degrees. They are pretty slow compared to heat pumps or gas heaters. They are also much more effective if coupled with a solar heater.

Estimated Cost

Solar domes are pretty cheap, mainly because you will not be paying any ongoing costs. Small, simple models designed for above ground pools will set you back $150-$250, while larger solar domes will cost around $250-$350.

Pros

  • Cheap initial purchase and no ongoing costs
  • Great affordable option for smaller pools

Cons

  • Not as effective for larger pools
  • Much slower at heating up pools than other options

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Frequently Asked Questions

What’s the fastest way to heat a pool?

The fastest way to heat a pool is by using a gas heater. They may not be the most economical or environmentally friendly option, but if it is the efficiency you are after, gas heaters are the best option for you.

How fast does a pool heat up naturally?

There isn’t an easy straight answer for this. Your pool will naturally heat depending on the outside air temperature and the UV index. On a 90-degree sunny day in July, you will notice your pool heating up to extremely warm temperatures, but it will not warm up as fast on a cloudy day.

Have more questions? Drop me a line. Head over to my article on the best pool heaters for specific options and make sure to check out my pool heater sizing guide to help you find the right one for your swimming pool.

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