How Long Does It Take for a Pool to Heat Up by the Sun?

Who needs a pool heater when you can heat your pool with sunlight? But is it really useful? If you also have similar questions in your mind, then all your questions will be answered in this post. Heating a pool by the sun is the most affordable way to enjoy a warm bath in your collection; however, is it enough to enjoy the sweet warmth of the water on your pool?

Well, it is possible to enjoy a hot bath in your pool by using solar energy to heat it and set it to the ideal pool water temperature. With an effective setup, you can enjoy your free heater whenever you want (at least in the daytime).

Heating a pool with sun

So, how long does it take a pool to warm up? If you want to heat a pool with the sun, you need a proper solution. Your pool must be able to absorb the heat to warm the pool water. All you need is a black water hose for the stream. Connect it to your tap and leave it in the direct sunlight. It absorbs the heat energy and gives you warm water when it comes out of the tap. 

black water hose to heat swimming pool
Black Water Hose

Although this process is slow, you can still heat water for free. On average, time to take for a pool to heat up by the sun is 8 to 12 hours. Also, note that you may not get your desired temperature only with the sun. You can increase its heating rate and more temperature by using a solar cover.

A solar cover traps the heat and keeps the pool water warm. This process requires a one-time investment and works without any maintenance cost.

ways to heat a pool

Factors affecting the heating of your pool water by sun

As we mentioned earlier, it takes around 8-12 hours for a pool to heat up by the sun. However, the numbers can vary as many other factors can influence this process. 

Water temperature

The starting water temperature of the pool plays a crucial role in it. If the water is warmer than the average temperature, it will take less time to heat the sun’s pool water. On the other hand, if it is colder than the average water temperature (less than13-degree Celsius), then you may need to wait a little longer to enjoy your pool bath.

Size of your swimming pool

If your pool size is bigger, that means you need more time to heat your pool. To increase your pool temperature, you need more calories. According to the theory:

A calorie is the amount of heat it takes to raise the temperature of 1 gram (0.001 liters) of pure water 1 degree C at sea level. It takes 100 calories to heat 1 g.

If you have a larger pool, which means it can hold a larger amount of water, therefore, your pool needs extra time to absorb the required amount of calories or energy from the sun.

Pool water vs surrounding air temperature

If the atmosphere is hot, cold water will receive the energy and warm up quickly with the help of the sun; however, if the surrounding air temperature is cold, you need more time to heat your pool water.

For this reason, it’s important to consider the Water Temperature vs Air Temperature of your pool.

Heat loss

Every material has a different ability to absorb heat. Hence, heat loss can be another crucial factor in this process. You can improve the heat by using a solar sheet to absorb the sunlight for a longer time.

Sunlight angle

The best angle to heat a pool by the sunlight is 90-degree. If it deviates from this angle, you may see a decrease in the pool water’s heating rate.

How long does it take to heat a pool?

We previously discussed there are several factors that determine the time to heat a pool. There are several ways to heat pool water and in every process, the heating time depends on many factors.

It’s really difficult to answer it shortly, as you need to know the volume of water, air temperature, heater capacity, sunlight angle, and heat loss percentage.

That’s why the answer is very simple as well as complex. Lets cover your answers in the below discussion.

How long does it take to heat pool

How long does it take to heat a pool with solar panels?

Using solar panels is another excellent way to heat the pool water conveniently. It costs you some money to buy and install your solar panels, but effective heating makes it up for all the struggle and expenses.

The best thing about this solution is that you can enjoy the warm water for a longer time. If on a location of average weather temperature is between 20°C to 28 °C and the size of an inground pool is 15 Feet by 30 Feet and assuming that, it can hold up to 13000-15000 Gallon of water, then, solar heating can warm by around 2.0-3.5ᵒ C in a day. Use a wireless pool thermometer to check the time it takes to get your preferred water temperature.

Let’s explain it with another example; if you are in Southern California and the time is the beginning of spring, then, you need only 2-3 days to reach 26°C to 30 °C (78° F to 85° F) on an average size pool. On the other hand, if you are from New York, you may need at least 5-7 days to reach that level.

Tip: Consider purchasing a glazed solar panel instead of an unglazed panel, you will get your desired temperature pretty fast with the glazed solar panel. You may also consider using a pool cover at night time.

How long does it take for a pool to warm up with a heater?

The heating time of a swimming pool with heater or heat pumps depends on a few factors, such as heater or heat pump capacity, pool size, air temperature, and your desired temperature. 

Heater or Heat Pump Capacity

To reduce your pool heating time, you can follow the heat pump sizing chart, if you are interested in a pool heater, then check for the accurate pool heater size. Every heater or heat pump manufacturer provides a clear sizing chart according to pool size vs required BTU or Kw.

Pool Size

A larger pool will require more time, however, if you have enough size of heater or heat pump, then, 8-12 hours is enough for a medium-sized (12000-15000 Gallon) inground pool.

Air Temperature

Surrounding air temperature is also a factor, especially, if you are heating with a heat pump, as the heat pump collects the heat from the surrounding air. For better efficiency of a heat pump, air temperature should be above 10 degrees Celsius.

Although you can heat your pool water by direct sunlight, there are many other effective solutions to heat a pool. It is because sunlight takes a lot of time to heat the pool water. Getting an above ground pool heater can save you a lot of struggle in heating your pool water. Hence, you can use a solar panel or gas heater for the job. It will reduce the heating time and keep the water warm for a longer time. 

That is why experts believe that using a gas heater is the best way to heat a pool quickly.

How long does it take to heat a pool without a heater?

If you don’t have a heater, the best option to heat a pool without a heater is the sunlight. A solar cover is perfect if you want to minimize the evaporation and do the healing process fast without a heater.

As previously discussed, If you want to increase or warm up the pool temperature around 2-3 degrees Celsius, normally it will take 7-10 hours.

What is the best way to heat the pool water? Solar panels or gas heater or heat pump? 

A solar panel heater traps the sunlight and uses it to heat the pool water with its pump and filter. It requires a one-time investment and heats your pool for free for a long time. On the other hand, a gas heater uses fuel to heat the water. Hence, this process is way faster than solar panels but requires much more investment than a solar panel.

You will need to add natural gas every time you want to heat your pool with your gas heater.

Final words

Heating the pool water with the sunlight is practical. Sunlight will also help you to reduce pool chlorine level on your pool However, you need some patience as the process may take up to 10 hours to heat it completely. That is where you can use other options like a Solar panel heater and gas heater. They are much more effective and provides better results in a short time.

People looking for a one-time investment can choose a solar panel heater as it comes with minimum maintenance costs. On the other hand, you can use a gas heater for quickly heating your pool water with some additional fuel costs.

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