Warm It Up: How Long Does it Take to Heat a Pool?

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As we enter the pool season, there are many people that want to know how long it takes to heat a pool. This is an important question for anyone who wants to enjoy their pool throughout the summer. There are a few different factors that come into play when determining how long it will take for your pool water temperature to reach desired levels.

A heat pump will generally heat a pool within 24 to 72 hours by 20 degrees Fahrenheit. This will depend on factors though like the BTU output of your heater and the overall size of your pool and the water volume. For smaller pools like a spa pool, a heat pump can heat it in 45 to 60 minutes. 

This shows that knowing the volume of your pool along with your pool heater BTU rating is very important. If you have this information you will be able to determine how long it will take to heat your pool.

How Long Does It Take to Heat a Pool?

No one wants to swim in a chilly pool, especially when pool heaters are available, and if you have a heater, I’m sure you don’t want to play the waiting game.

Swimming pool heaters have long been associated with high expenditures, but they are becoming increasingly popular among pool owners all around the world. Pool heaters provide warmth to your swimming experience and may keep your pool open for weeks longer.

“How long does it take to heat a pool?” is one of the most frequently asked questions we get from pool owners. This is an essential question since it informs pool owners about what size pool heater they require and how far in advance they should start their heater so that it is warm enough to swim.

In general, buying a pool heater that is insufficient for the amount of water in your pool is ill-advised. Even if only for financial reasons, understanding how long it will take to heat your pool is recommended.

When you have a properly rated BTU pool heater you will be able to heat your pool within 24 to 72 hours. This is assuming that the weather conditions are normal and at least half of your pool cover has been removed; these two factors play a significant role in how fast water heats up.

If you live somewhere where it’s cold or if you have an above-ground swimming pool, then heating time will be longer than this.

For example, smaller pools like spa pools can be heated in 45 to 60 minutes with a heat pump, but it will generally take longer for larger pool surfaces that are cold (or if your cover is on).

When you know how long it takes to heat a pool and the BTU output of your heater you will also understand what size pool heater you require.

In order to determine how long it takes for your pool water temperature to reach desired levels, you need to know the volume of your pool and its BTU output rate in addition to the size of your swimming area.

You can easily calculate this information with a few measurements or use free online calculators that are available on several pool equipment dealers’ websites.

Are You Purchasing a Heater Or a Heat Pump?

How long does it take to heat your pool is determined by a few variables. Have you decided if you’re getting a heater or a heat pump? Yes, they both heat your pool, but they do so in very different ways. Let’s dig in.

The heaters in thermal pools don’t create their own heat, but instead, they draw heat from the ambient air and use it to warm your pool water.

If you reside in a colder environment, this may be an issue. Heat pumps function best when the temperature is greater than 50 degrees Fahrenheit. Heat pumps are unable to efficiently execute in temperatures below 50 degrees Fahrenheit.

Because of this, pool owners must run their heat pumps for a longer period of time in order to warm the water. As a result, it’s critical to take into account the average temperature in your region, especially during the winter months, before purchasing a heat pump.

In the event that your heat pump is too small, it will have to work longer in order to heat the pool. Longer running times result in lower efficiency and greater operating costs. In a nutshell, it’s a no-win situation, so go with a gas heater instead.

Calculating Heat Run Time

A heat pump’s or heater’s efficiency is determined by the British Thermal Units (BTU) per hour. This measurement is pretty simple once you understand that one BTU raises one pound of water by 1 degree Fahrenheit.

One gallon of water weighs 8.34 pounds. So to raise the temperature by one degree Fahrenheit you would need 8.34 BTUs.

BASE FORMULA: Determine the time required to increase water temperature by 1 degree F # of gallons in pool X 8.34 = ___________ lbs. of water ______ pounds of water / BTU Size = The hours it takes to raise the water temperature by 1 degree F

EXAMPLE: You have a 20,000-gallon pool and use a 125,000 BTU heater. Your water is currently 70 degrees F but you would like it to be a minimum of 80 degrees F. How long will it take before the pool water reaches 80 degrees F?

20,000 x 8.34= 166,800 lbs 166,800/125,000= 1.33 hrs to increase 1 degree 80-70= 10 degree difference 10 x 1.33= 13.34 hours of heating before the pool reaches 80 degrees F.

In most cases, heat pump and heater calculations are overly optimistic. The efficiency of a heat pump varies with the air temperature, thus colder temperatures cannot be accounted for in the figures. When the air is extremely hot,

The efficiency of gas heaters is also reduced, however they are more consistent. They are only around 80% efficient, so you must consider it. Also, you can always anticipate losing heat overnight, extending your overall heating period.

When it comes to determining how long it takes to heat up your pool, there’s no need to be overly precise. It’s always a good idea to round up when calculating the amount of time it will take for your pool to heat up using this formula since heat loss and efficiency are taken into account. The calculation provides rough estimates rather than precise timing

What’s The Cost Of Running A Pool Heater?

Many looking to use their pool heater or looking to maybe add a pool heater to their existing pool may wonder, what are the costs are to run a pool heater?

Propane Heaters

Propane Pool Heaters Burn approximately 1 gallon each hour for every 100,000 BTU. For a 400,000 BTU heater, that comes to 4 gallons per hour. Propane costs between $4.50 and $5 per gallon recently, this can change.

Since prices can change, you should contact your service provider and ask.

It takes around 8-14 hours to heat a pool with a volume of 10-12K gallons and no solar cover. You may substantially improve the heating process’s efficiency by adding a solar covering to your pool while heating.

Natural Gas Pool Heaters

Natural gas heaters (also known as NG or natural gas heaters) utilize around 1 therm per hour for every 100,000 BTU. For a typical 400,000 BTU pool heater, that’s four therms per hour.

The cost of natural gas in the United States is currently approximately $1.50 per therm. The typical cost to heat a pool for one hour using natural gas is around $7.00.

An average pool (10-12K Gallon) without solar cover takes 8-14 hours to heat with natural gas. You may greatly increase the efficacy by adding a solar blanket to your pool during heating.

Heat Pumps

It takes approximately 5,000 watts or 5 kilowatts per hour for every 100,000 BTUs in a heat pump. For a typical size 100,000 BTU heat pump, that’s 5 kilowatts per hour.

For electricity, the average price in my region is around $.16 per kilowatt-hour. Electric rates are determined by your utility supplier, so double-check yours if necessary.

Under our example, heating a pool with a heat pump for an hour will cost about .80 cents. A typical pool (10-12K gallons) should be heated at a rate of 1 to 1.5 degrees per hour without solar protection.

As with other heaters, you can increase the efficacy by adding a solar blanket to your pool.

Things That Can Influence Pool Heating Time

There are many things that can influence the speed at which a pool can be heated.

The air temperature, wind speed, and precipitation can influence the rate at which a pool receives heat from its surroundings.

Air Temperature:

Most air-source heat pumps operate on the principle of using heat from the air to warm your swimming pool or spa. Heat pumps are most efficient when the temperature is above 50°F (10°C). Because heat pumps cannot effectively capture heat from the air at temperatures below 50°F (10°C), they need additional time to warm your

The performance potential of a pool heat pump is directly linked to the temperature of the outside air. Air-source heat pumps, since they extract heat from the environment, tend to work better in higher temperatures.

The majority of pool heat pumps function well down to 50 degrees Fahrenheit (more advanced versions can operate down to 40 degrees). However, as the temperature drops, a pool heat pump must work harder and longer to draw in warmth, affecting how fast your swimming pool warms up.

Swimming Pool or Spa Size:

This may seem like common sense, but it’s essential to remember nonetheless. Overall, the larger a body of water is, the longer it will take to warm up. Of course, the present temperature of the water when it’s heated also has an impact, which leads us to the next point.

The size of the pool pump is usually determined by its BTU. It is a unit of power in air-conditioning and heating industries.

Despite what you may have heard, there is no “best” number of BTUs for a pool. Although higher BTUs usually indicates a more efficient device, this isn’t always the case. For example, the Oasis Platinum has 105,000 BTU and outperforms the top-selling 125,000 BTU devices by 60%.

Current and Desired Water Temperatures:

The greater the gap between your present and desired water temperatures, the longer you’ll need to run your heat pump.

It shouldn’t take very long to get up to 80 degrees if your swimming pool has been sitting in the summer sun at a comfortable 70 degrees Fahrenheit.

However, if you’re only entering your pool from its winter hibernation, the water will most likely be too cold to swim in right away. It will take longer to get the temperature to a pleasant level.

Use of a Solar Blanket:

Solar blankets likewise save money on swimming pool and spa heating while also cutting down the time it takes to heat the water. Seventy-five percent of a swimming pool’s heat loss is due to evaporation.

A solar blanket retains heat in a swimming pool or spa by reducing evaporation. It serves as a barrier between the air and your swimming pool or spa.

You now know some things that affect how long it takes to heat up your pool or spa. Keep in mind, however, that each pool and spa is different. The time it takes to heat up a pool or spa can vary greatly.

Pool covers are a wonderful way to extend the life of your pool and improve its energy efficiency. Pool covers aid in the reduction of evaporation by limiting and, in many cases, preventing it entirely.

Because the cover acts as a heat barrier, maintaining pool temperature is much simpler when using a pool cover.

Can I Leave Pool Heater on Overnight

The size of your pool’s heater and the cost of heating your pool are both affected by whether or not you leave it outside overnight. People usually suggest a pool water temperature of 78°F to 82°F, depending on the necessity for your pool to swim.

However, if your pool is maintained at about 78°F, you will save money on energy use while being safe for children and the elderly.

However, if you want to use the pool in the morning, leaving the pool heater off at night would not be beneficial because the night-time temperature of the pool would plummet rapidly, necessitating a higher heat rate when you want to use it.

Is it Better to Run a Pool Pump at Night or Day?

Because it confuses individuals about the choice to take, this is a question that many people have. However, there are certain things you should know.

Running your pool pump at night is a fantastic alternative, but it isn’t necessary and may cost you time and money. It would also assist in the formation of algae since they require heat to develop,

The best way to utilize your pool pump is to let it run for a set amount of time at a specific temperature. So, if you want to use the pool in the afternoon, you can run it for at least an hour at a certain heat level and store the energy by covering it with a solar blanket after.

Final Thoughts on how long does it take to heat a pool

In conclusion, it takes a lot of time and effort to heat up a pool depending on the size of your pump. If you’re running into some trouble with how long it’s taking for your pool to get heated, try using solar blankets or covering them at night when they aren’t being used.

Pool covers are another great way to cut down evaporation while saving energy costs in the process.