How long does it take to heat a pool?

It is almost impossible to say precisely how long it will take to heat a pool. Why? Primarily thanks to the fact that the weather and the pool’s ambient temperature always affect the heating time. 

In this post, McCallum’s Pool Service discusses how most pools can take a few hours to reach a comfortable average temperature with the right combination of factors.

Factors that Affect the Pool’s Temperature

The Size of the Pool

When heating a pool, the measure refers to British Thermal Units or BTUs. It is the pool size that largely determines the BTUs required to heat a certain volume of water. So, larger pools would require more BTUs than a smaller volume of water to reach the same temperature.

According to Consumer Reports, a 10 x 30 ft. rectangular pool needs between 3,600 and 7,200 BTUs of energy per hour to keep the water at a toasty 80° F. That is a fairly small pool. A larger pool (say 40 x 18 ft.) requires between 8,400 and 14,100 BTUs to reach the same level of comfort.

The Pool’s Water Level

How does the water level affect the time expectation? If the water level is too low, the heat will not reach the deepest parts of the pool. 

Any warmer air above the pool holds more moisture than cooler air. So, maintaining a consistent water level in the pool will prevent the water from cooling too quickly during colder spells.

The Shape of the Pool

The shape of the pool also affects the surface area of the water. 

• A deeper pool takes longer to warm up.
• Round pools take longer to warm up than rectangular ones due to the surface area.

The Power Source

What is your preferred power source for pool heating? The choice has a huge impact on how long the process takes. For example, the sun is an excellent source of natural energy for heating pool water but not a practical source of heat to use year-round. 

At McCallum’s Pool Service, we typically recommend a combination that suits your pool setup:

• Sun: The sun’s rays can heat the pool’s surface quickly but cause discomfort and sunburn. 
• Solar: Panels provide an alternative that may take longer to heat a pool but provide a steady, more energy-efficient heat source than gas-powered heaters. Solar panels also run automatically using a timer or sensor to prevent heat loss.
• Heat Pump: A pool heat pump can be a useful source of supplemental heat if the water temperature drops below the desired level. It transfers heat from the outside of the pool to the inside using a refrigeration cycle. Like a refrigerator, a heat pump uses an electric motor and a compressor to move the refrigerant through a system of coils.

A solar cover or solar blanket is also a great addition to prevent the water from cooling too quickly at night.

Local Weather

Another factor that can affect the temperature level of your pool is the weather. During the summer, the temperature on the pump won’t need to be as high. Depending on your location, the pool may not even lose all its heat during the warmer nights. 

Winter is an entirely different story. The pool heating source will need careful adjustment to keep the water temperature comfortable for over twenty-four hours. Weather conditions like rain or cloud cover also vary the pool’s ambient temperature, and you will need to adjust the heating system accordingly.

So, How Long To Heat The Pool?

Though the time changes for all the abovementioned reasons, the average pool will only take between a few hours to several days to reach your desired temperature. The best approach is to raise the water’s temperature gradually until it reaches your target temperature while finding ways to reduce pool heating costs.

Why not consider using a solar heater? It is a natural way to increase the energy efficiency of your heating system. If you go this route, reducing the amount of chlorine in the water may also reduce your energy consumption needs. 

The most important thing to remember is to only heat the pool within the recommended limit. Otherwise, you risk damaging the infrastructure.

McCallum’s Pool Service has over 23 years of experience servicing pools in Arizona. Would you like to know more? Call us at (480) 734-2495 today to learn more about how to heat a pool so that it is ready for a relaxing dip even in the wintertime.