How Long to Heat Your Pool: Expert Guide to Cut Heating Time in Half

Ever fired up your pool heater only to wonder when you'll actually get to swim? You're not alone in this frustration.

The honest answer about pool heating time is one that might make you groan: it depends. Your pool could heat up in just 8 hours with the right gas heater, or you might find yourself waiting up to 48 hours if you're using a heat pump.

If you’re using a gas heater, your pool could be ready in 8-12 hours. But if you’re using a heat pump, you’ll need more patience – it can take anywhere from 10 to 24 hours to warm things up. With solar heating demands even more waiting—sometimes several days to reach comfortable swimming temperatures.

Your average-sized pool sits between 15,000-20,000 gallons. Expect to wait anywhere from 8-48 hours for that sweet 10-20 degree temperature boost. A standard rectangular 16×36 pool with a decent 300k BTU heater will warm up about 10 degrees in roughly 6 hours.

At Shasta Pool Supply, we get it. Nobody wants to stare at their pool while waiting for it to warm up. Pools are meant for fun, not endless waiting games. That's exactly why we've put together this guide—to show you the factors that really affect heating time and share the proven strategies that can cut your waiting time in half. 

Pool heating times vary wildly, and there's a good reason for that variation. Your average-sized pool holding 15,000-20,000 gallons will need anywhere from 8-48 hours to warm up by 10-20 degrees Fahrenheit. That's a huge range, and understanding why can save you both time and money.

Average heating time by heater type

Gas heaters dominate the speed game. These workhorses can push your pool temperature up by 1-2.5°F every hour. Heat pumps take a more patient approach, bumping temperatures by just 0.5-1.5°F hourly. Solar heaters? They're the marathon runners of pool heating—adding about 2-4°F per sunny day.

Here's what those numbers mean in real time when you're aiming for that perfect 80°F:

Starting at 60°F:

• Gas Heater: 14-28 hours
• Electric Heat Pump: 28-40 hours
• Solar Heater: 40-60 hours

Starting at 70°F:

• Gas Heater: 10-20 hours
• Electric Heat Pump: 20-32 hours
• Solar Heater: 32-48 hours

“One of the biggest things people overlook when asking how long it takes to heat a pool is heat loss,” says Dan Panfili, a pool industry veteran with more than 20 years of hands-on experience. “If your heater isn’t sized properly for your pool or you’re not using a solar cover, you’re losing heat every day. That’s going to dramatically increase how long it takes to reach your target temperature.”

Want to boost your pool temperature by 10 degrees? A gas heater will get you there in 8-14 hours for a typical 20,000-gallon pool. Heat pumps need considerably more patience—expect 24-72 hours for the same temperature jump. Solar systems might keep you waiting several consecutive sunny days.

We've seen how much difference a simple pool cover makes at Shasta Pool Supply. That single addition can slash these heating times by preventing the heat loss that happens through evaporation.

Why do pool heating times vary so much?

Several factors determine whether you're swimming tonight or waiting until next weekend.

Pool size creates the foundation for heating time. Bigger pools hold more water, and more water means more energy and time to reach your target temperature. Your starting temperature sets the baseline—jumping from 60°F to 80°F takes significantly longer than going from 70°F to 80°F.

“A lot of heating time comes down to setup, not just the heater itself,” says Dan Panfili, who has spent more than 20 years maintaining pool equipment for long-term performance. “If the heater isn’t sized properly for the pool, or you’re not keeping the heat in with a solar cover, you’re going to lose heat every day — and that changes how long it takes to warm the water.”

Climate plays a starring role here in Arizona. Our pools heat faster than those in cooler states because ambient temperature directly affects heating efficiency. Wind exposure works against you by accelerating heat loss, forcing your heater to work overtime.

Pool insulation makes the difference between efficient heating and energy waste.

Properly insulated pools with quality covers hold onto heat effectively, cutting both heating time and operational costs.

What makes a pool heat up faster or slower?

Factors That Affect Pool Heating Time

Your pool's heating time isn't random—specific factors determine whether you'll be swimming tonight or waiting until next weekend. At Shasta Pool Supply, we've seen how these six critical factors make the difference between hours and days of waiting.

Your heating system choice fundamentally determines how fast your water warms up. Gas heaters work fastest, cranking up temperatures by 1-2°F per hour. Heat pumps move more slowly at 0.5-1°F hourly, while solar systems depend entirely on sunshine availability.

Gas heaters maintain desired temperatures regardless of weather conditions, making them perfect for weekend warriors or unexpected pool parties. Heat pumps, though slower, typically last 10+ years with proper maintenance—think of them as the marathon runners of pool heating.

Pool size and water volume

Bigger pools need more time and energy to heat. It's simple math, really. A small pool will warm considerably faster than one with double the water volume. Deeper pools contain more water to heat, extending the process even further.

We've learned that correctly matching your heater size to your pool's dimensions prevents the frustration of inadequate heating performance. Too small a heater for a large pool? You'll be waiting forever.

Starting water temperature

The gap between your current water temperature and your target makes all the difference. Raising water from 60°F to 80°F takes substantially longer than from 70°F to 80°F. This is why pools maintained at moderate temperatures year-round heat up faster than those starting from cold.
Think of it like warming up your car—starting from freezing takes longer than starting from cool.

Local climate and weather

Weather conditions dramatically impact how efficiently your heater works. Heat pumps function optimally above 50°F, losing effectiveness when temperatures drop. High humidity can reduce heat pump efficiency, while wind exposure accelerates heat loss, forcing longer heating times.

Here in Arizona, our customers typically experience faster heating cycles throughout most of the year. But even in the desert, those windy spring days can slow things down. 

Pool covers represent the single most effective way to reduce heating time, cutting costs by 50-70%. They minimize evaporation—the primary source of heat loss—while trapping warmth. Cover your pool whenever it's not in use and you can reduce water and chemical consumption by 30-50%.

This isn't just about saving money. It's about getting to swim sooner.

“A lot of what people experience as ‘slow heating’ isn’t always the heater itself,” Panfili explains. “If you’re not holding onto the heat you’re producing, the pool is going to take longer to warm up regardless of the system.”

Pool location and exposure to sun

South-facing pools receive maximum sunlight, naturally staying warmer. Properly positioned pools require less artificial heating, lowering operational costs. Shade from trees or buildings increases heating time—something many homeowners don't consider when planning their pool area.

Even heat pumps themselves should be installed in sunny locations with good airflow for optimal performance. Location matters more than most people realize.

Different heating systems work at completely different speeds. At Shasta Pool Supply, we help Phoenix Valley customers choose the right system based on how fast they need their pool heated and how often they plan to use it.

How fast can a gas heater warm up my swimming pool?

Gas heaters are the speed champions, cranking up water temperature by 1-2.5°F per hour. Start with a 70°F pool, and you're looking at 10-20 hours to hit comfortable swimming temperatures.

The real advantage? Weather doesn't matter. Gas heaters work just as well on a cloudy February day as they do in blazing July heat, making them perfect for spontaneous pool parties or weekend heating. The fastest gas systems can actually warm smaller pools in as little as 4 hours.

Is an electric heater fast enough to heat my pool?

Electric resistance heaters match gas models for speed. They deliver consistent performance but cost significantly more to operate, which is why most pool owners skip this option entirely.

How long does a heat pump really take to heat a swimming pool?

Heat pumps play the long game, needing 12-48 hours to warm your pool while raising temperature just 0.5-1.5°F each hour. First-time heating? Plan on running that pump for 3 straight days.

Here's how they work: heat pumps pull warmth from the air around them, which makes them incredibly efficient but also slower. Think of them as the marathon runners of pool heating—steady, efficient, but definitely not built for speed.

How long does Solar heating take to heat a pool?

Solar systems require the most patience, typically needing 3-7 days to reach comfortable swimming temperatures. Smaller pools around 10,000 gallons might warm up in 1-2 days when conditions are ideal.
The catch? "Ideal conditions" means consecutive sunny days with minimal cloud cover. One cloudy stretch can set you back to square one. 

You've been patient long enough with slow heating times. Here are the strategies that actually work to get your pool warm faster.
At Shasta Pool Supply, we've watched Phoenix Valley pool owners cut their heating time dramatically with these proven approaches. No more waiting days for warm water.

Use a thermal pool cover

This is your secret weapon. Thermal pool covers slash heating costs by 50-70% and retain up to 90% of your pool's heat. Think about it—evaporation is what's stealing most of your heat, and a good cover stops that problem cold.

Simply covering your pool when you're not swimming cuts water evaporation by over 98%. That's money staying in your pocket instead of evaporating into thin air.
Upgrade to a high-efficiency heater

Modern gas heaters are impressive machines, achieving 89-95% efficiency ratings. When you fire up one of these units, 96 cents of every dollar you spend on natural gas goes directly into heating your pool.
Look for models with titanium heat exchangers—they resist corrosion better and last longer. It's an investment that pays off in faster heating and fewer repairs.

Run heater during warmest part of the day

Your heater works harder when it's fighting cold nighttime temperatures. Run it during daylight hours instead, especially if you have a gas or solar system.

Unless you have a pool cover. Without one, nighttime heating just sends your money floating away as heat loss.

Install windbreaks or barriers

Wind makes your pool lose heat fast – kind of like taking a blanket off on a cold day. Even small fences or shrubs can help block the wind and keep the warmth in, for a longer period of time.

Strategic landscaping—a few well-placed shrubs or a privacy screen—creates natural windbreaks that keep your heat where it belongs. Since wind accelerates evaporation, even small barriers make a noticeable difference in heating efficiency.

Use smart thermostats and timers
Programmable pool heater controllers let you manage heating from your phone and typically reduce energy consumption by about 15%.

Set them to run during off-peak hours when electricity rates are lower. Smart timing means faster heating and lower bills—exactly what you want. 

When it comes to heating your pool, there’s no single timeframe that fits every backyard. First, your pool’s size determines how much water needs to be warmed. Next, your heater type controls how quickly that temperature can rise, and the weather sets the conditions everything operates within. A smaller pool with a powerful gas heater on a warm, sunny day will heat far faster than a large pool.

Understanding how these factors work together helps set realistic expectations and prevents frustration. It also helps make better decisions on the right pool heater. Now, we hope you can chose the right heater and using a pool cover to retain heat. With the right setup, you can achieve comfortable swimming temperatures.

Shasta Pool Supply helps pool owners enjoy their pools longer, smarter, and with fewer surprises. When you know what influences pool heating time, you’re taking control of your pool experience.

Pool heating doesn't have to be a waiting game. With the right strategies and equipment, you can significantly reduce heating time and enjoy your pool sooner.

• Gas heaters are fastest: Heat pools 1-2.5°F per hour, taking 8-12 hours versus 12-48 hours for heat pumps
• Pool covers cut heating time in half: Thermal covers reduce heating costs by 50-70% by preventing evaporation
• Size matters for timing: Average 15,000-20,000 gallon pools need 8-48 hours to raise temperature 10-20°F
• Smart timing saves energy: Run heaters during warmest daylight hours and use programmable controllers for 15% energy saving
• Multiple factors affect speed: Pool size, starting temperature, climate, and wind exposure all impact heating efficiency

The key to faster pool heating lies in combining the right equipment with smart operational strategies—invest in a quality thermal cover and match your heater type to your usage patterns for optimal results. 

Gas Pool Heaters - https://www.energy.gov/energysaver/gas-pool-heaters

Swimming Pool Covers - https://www.energy.gov/energysaver/swimming-pool-covers

Heat Pump Swimming Pool Heaters - https://www.energy.gov/energysaver/heat-pump-swimming-pool-heaters