How to Heat an Above-Ground Pool: Cheapest & Most Efficient Options
Updated: Sep 30
Cold pool water does not always mean you need a bigger heater.
Sometimes the cheapest improvement is simply stopping the heat you already have from escaping overnight.
That distinction matters with above-ground pools because the water is exposed to changing air temperatures, wind and evaporation. You can spend money heating the water during the day, then lose a surprising amount of that warmth once the sun goes down.
So before choosing a heater, ask yourself what you actually need:
Do you need to add more heat, retain more heat, or both?
For many above-ground pool owners, the best setup is not one heating product. It is a heater or solar system paired with a good pool cover.
Quick Answer: What Is the Best Way to Heat an Above-Ground Pool?
There is no single best heating method for every pool.
Use this as a starting point.
In short, a solar cover is the cheapest place to start, a heat pump is usually the stronger choice for efficient season-long heating, and gas or propane makes more sense when heating speed matters most. Pool size, climate and overnight heat loss determine how well any of them will actually perform.
Before Buying a Heater, Work Out Where the Heat Is Going
Imagine your pool reaches 82°F on a sunny afternoon but drops to 74°F after a cold, windy night.
You can install a larger heater and put those eight degrees back every morning.
Or you can first reduce how much heat disappears overnight.
Those are very different solutions.
Evaporation from the water surface is one of the biggest sources of heat loss from a swimming pool. Wind makes that worse because it continually moves warm, humid air away from the water surface.
That is why a cover can make such a large difference even though it contains no heater.
If your pool already warms reasonably well during the day but loses that warmth overnight, focus on heat retention before spending more money on heat generation.
1. Start With a Solar Pool Cover
For most above-ground pools, this is the cheapest heating-related upgrade we'd make.
A solar cover floats directly on the water surface and reduces exposure to the surrounding air.
Its main advantage is not that it magically generates large amounts of heat.
It helps reduce evaporation and slow heat loss.
That becomes particularly valuable overnight, during cooler weather and in windy yards.
If you're already running a heat pump or gas heater, a cover can also reduce how much work the heater has to do to maintain the temperature you've already paid to reach.
A Solar Cover Works Even Better With a Heater
Think about the two jobs separately:
Heater: puts BTUs into the water.
Cover: helps stop those BTUs escaping again.
That is why a solar cover makes sense with almost every powered pool-heating system.
For a lightweight option for common round frame pools, see our Intex Solar Pool Cover guide.
If you want a thicker cover with more size and insulation choices, our VEVOR Round Solar Pool Covers guide compares 8mm, 12mm and 16mm options.
Rectangular pool owners can use our VEVOR Rectangle Solar Pool Covers guide instead.
Can a Solar Cover Heat a Pool by Itself?
Sometimes it can make the pool noticeably warmer, but we would not expect one fixed temperature increase from every pool.
Results depend on:
sunlight;
daytime temperature;
nighttime temperature;
wind;
pool surface area;
pool depth;
cover design;
and how consistently you use it.
A small shallow pool in full sun can respond very differently from a large deep pool in a windy yard.
A solar cover is best thought of as a heat-retention tool that can also support solar warming. The actual temperature increase will vary with sunlight, weather, wind, pool size and how consistently the cover is used.
If you want active, controllable heating rather than relying mainly on sunlight and heat retention, a powered pool heater is the better option.
What About Liquid Solar Covers?
If you dislike handling a physical solar blanket, a liquid solar cover is another option.
These products create a very thin layer at the water surface intended to reduce evaporation.
Their biggest advantage is convenience. There is no heavy cover to remove before swimming or roll back onto a reel afterward.
The trade-off is that a liquid cover generally does not provide the same level of heat retention as a properly fitted physical pool cover.
We would treat a liquid solar cover as a compromise for someone who knows they are unlikely to use a traditional cover consistently.
A physical solar cover remains the stronger option when maximum heat retention is the priority.
2. Solar Heating Mats: Cheap Heat When the Sun Cooperates
A solar heating mat is different from a solar cover.
Instead of sitting on the pool water, a solar mat connects to the circulation system. Pool water flows through dark channels where sunlight warms it before the water returns to the pool.
There is no fuel bill for the heat itself.
That's the attraction.
The limitation is equally straightforward:
No strong sun means very little useful heat.
Solar mats also become less convincing as pool volume increases.
Heating 2,500 gallons with a sunny mat is a very different job from trying to warm 12,000 gallons.
You Can Connect Multiple Solar Mats Together
One advantage of the Intex Solar Heater Mat is that you are not limited to using a single collector.
Multiple mats can be connected in series, so the pool water flows through one solar mat and then into the next before returning to the pool. This increases the total collector area exposed to sunlight and can increase the amount of solar heat transferred to the circulating water.
That can make a multi-mat setup much more useful than expecting one small collector to heat a larger pool by itself.
The number of mats you can connect depends on the filter-pump flow and the manufacturer's instructions, so don't simply keep adding mats without checking the recommended setup. Every additional mat also adds some resistance to the circulation system.
For a smaller pool, one or two mats may be enough to provide a useful boost. For larger pools, several collectors can make more sense, but there is a point where the cost, space and extra plumbing make a proper heat pump worth comparing instead.
If you have a smaller pool, plenty of direct sun and modest expectations, our Intex Solar Heater Mat review looks at one of the simplest low-cost options and explains how it fits into a typical above-ground pool circulation system.
For best results, we'd still pair the mats with a solar cover so the warmth collected during the day isn't quickly lost again overnight.
Solar Cover vs Solar Heating Mat
These products are often grouped together, but they do different jobs.
A solar cover mainly reduces heat loss from the water surface.
A solar heating mat actively transfers solar heat into circulating pool water.
If the budget allows, they can work well together.
If you can buy only one, we'd normally start with the cover, because retaining existing heat helps regardless of whether that warmth came from sunlight, a heat pump or a gas heater.
DIY Black-Hose Solar Pool Heater
If you are happy doing a little DIY, one of the cheapest ways to add solar heat is to circulate pool water through a long length of black hose or black irrigation tubing positioned in direct sunlight.
The principle is essentially the same as a commercial solar heating mat.
Sunlight heats the dark tubing, and some of that heat transfers into the water flowing through it before the water returns to the pool.
The important part is not simply making the return water feel hot.
It is creating enough solar collector area to transfer a useful amount of heat into the whole pool.
A short black hose may produce very warm water at the outlet, but if only a small amount of water is flowing through it, the effect on several thousand gallons of pool water may be limited.
For a more useful DIY setup, the tubing can be spread over a larger sunny area or arranged in several coils.
Improve the Collector With a Dark Backing
A basic black-hose collector can be made more effective by mounting the tubing on a dark surface.
For example, the tubing can be fixed to a board painted black or positioned over another dark backing material.
The dark surface absorbs additional solar energy and helps warm the area around the tubing.
The collector should be positioned where it receives strong direct sunlight for as much of the day as practical.
What About Putting Clear Plastic or Perspex Over It?
A more developed DIY collector can place a clear polycarbonate, acrylic or similar weather-resistant sheet over the black tubing.
This allows sunlight into the collector while reducing the amount of heat carried away by moving air, creating a simple greenhouse effect around the tubing.
This can be particularly useful in cooler or windy conditions.
However, an enclosed solar collector can become very hot when exposed to strong sun without water circulating through it. Make sure the tubing, fittings and cover materials are suitable for the temperatures they may reach, and do not create a sealed section of trapped water that can heat up under pressure.
For most pool owners, an open black-hose collector is the simpler starting point.
Hotter Return Water Does Not Always Mean More Pool Heating
It is easy to judge a solar heater by putting your hand under the return and seeing how warm the water feels.
But hotter return water does not automatically mean the pool is receiving more total heat.
A very slow flow returning water 15°F warmer may transfer less heat overall than a much larger flow returning water only 3°F warmer.
What matters is both:
the temperature increase and the amount of water moving through the collector.
That is why commercial solar pool heaters use a relatively large collector area and move a useful volume of water through it rather than simply restricting the flow until the outlet becomes extremely hot.
For the whole pool, total heat transferred matters more than an impressive outlet temperature.
Several Shorter Loops Can Be Better Than One Very Long Coil
An extremely long length of narrow tubing creates more resistance to water flow.
That means there is a point where adding more hose to one continuous coil can actually make the system less useful because the flow becomes too restricted.
For a larger DIY collector, several shorter loops sharing the water flow can be more practical than forcing everything through one very long narrow hose.
The goal is to create plenty of collector area without unnecessarily choking the circulation.
Don't Run a Solar Collector When It Is Colder Than the Pool
A solar mat or DIY black-hose collector can work in reverse.
If the collector is colder than the pool water, circulating warm pool water through it can actually remove heat instead of adding it.
That can happen:
after sunset;
early in the morning;
during cold cloudy weather;
or when the collector is heavily shaded.
For a simple manual setup, only send water through the solar collector when it is warm enough to add useful heat.
If the water returning from the collector is cooler than the pool water, bypass the solar loop until conditions improve.
More advanced solar-heating systems can use temperature sensors and automatic valves to do this for you.
What About a DIY Firepit or Copper-Coil Pool Heater?
You may have seen homemade pool heaters that circulate water through copper tubing positioned over a wood fire, propane burner or enclosed firepit.
The basic idea works because the hot metal transfers heat into the water flowing through the coil.
It can also produce much more concentrated heat than a solar collector.
The problem is that an improvised fire-based pool heater introduces risks that a purpose-built pool heater is designed to control.
If water circulation stops while the coil is still being heated, trapped water can become extremely hot. You also need to consider hot metal, combustible materials, hose and fitting temperature limits, ventilation, water-temperature control and the effect of chemically treated pool water on the heat exchanger.
An enclosed burner may reduce problems such as ash blowing toward the pool, but it does not remove the temperature, pressure, combustion or material-compatibility issues.
For that reason, we would not recommend circulating pool water through an improvised copper coil sitting in an open fire.
If you want to use wood, propane or another combustion heat source, a purpose-built pool heater or properly rated heat-exchanger system is the safer route.
3. Heat Pumps: Best for Efficient Season Extension
For many above-ground pool owners who want dependable powered heating, a pool heat pump is the option we'd look at first.
A heat pump doesn't create heat in the same way as an electric resistance element.
It moves heat from the surrounding air into the pool water.
That allows it to deliver more heat energy to the pool than the electrical energy it consumes.
This makes heat pumps particularly useful when you want to gradually raise the water temperature and then maintain it over days or weeks.
The trade-off is speed.
A heat pump is generally better at:
gradually raising and maintaining temperature
than:
turning a cold pool into a warm pool in two hours.
Heat Pump Efficiency Changes With the Weather
Heat pumps rely on heat available in the outside air.
When the air is warm, the unit has more heat available to move into the pool.
As ambient temperature falls, heating output and efficiency can also fall.
So don't choose a heat pump based only on a headline maximum COP or maximum pool-gallon rating.
Look at:
BTU heating capacity;
pool volume;
minimum operating temperature;
your typical outdoor temperature;
desired water temperature;
wind exposure;
whether you use a cover;
electrical requirements;
and how quickly you expect the pool to heat.
The manufacturer's maximum pool size tells you what the unit is designed to serve under its expected conditions.
It does not tell you how quickly it will heat that pool in your backyard.
Above-Ground Pool Heat Pump Options by Heating Capacity
These three AquaStrong heat pumps cover a useful range of heating capacities for above-ground pools:
The important point is not to choose the largest gallon rating your pool barely fits under. A heat pump near its maximum pool rating may still warm the water more slowly than you expect, particularly in cooler or windy conditions.
For a closer look at performance, installation requirements and practical pool sizing, see our individual reviews of the AquaStrong HEX018, AquaStrong 35,000 BTU HEX035 and AquaStrong 55,000 BTU HEX055.
4. Gas and Propane Heaters: Best When Speed Matters
Gas heaters solve a different problem.
If you use the pool occasionally and want to warm it quickly before swimming, high-output gas heating can make more sense than running a smaller heat pump gradually for a long time.
A 150,000 BTU gas heater has far more nominal heating capacity than an 18,000 or 35,000 BTU heat pump.
That makes gas particularly useful for:
quick warm-ups;
recovering after a cold night;
occasional weekend use;
and pools where waiting a day for gradual heating isn't practical.
The trade-off is operating cost and installation.
Natural gas and propane prices vary too much by location and time for one universal cost-per-hour figure to be useful.
You also need the correct fuel supply, plumbing, clearances and code-compliant installation.
For natural gas, see our Hayward H150 150,000 BTU Gas Pool Heater review.
If your setup uses propane instead, see our Hayward 150K Propane Pool Heater review.
A gas heater still benefits from a solar cover. Fast heating doesn't make heat loss disappear.
Heat Pump vs Gas Heater
The simplest distinction is:
Heat pump: better when you want efficient temperature maintenance over the season.
Gas or propane: better when you want a lot of heat quickly.
Neither is universally better.
If you swim almost every day and want to hold the pool around a comfortable temperature for weeks, a heat pump is usually the more natural fit.
If you use the pool mainly at weekends and want to warm it quickly when needed, gas becomes more attractive.
Your local electricity and gas prices can change the economics, so avoid assuming one technology will always cost a fixed amount less than another.
5. What About Electric Resistance Pool Heaters?
Electric resistance heaters turn electrical energy directly into heat.
That sounds simple, but for a swimming pool the amount of energy required can become substantial.
For a very small pool or spa-sized volume, resistance heating may be practical.
For a larger above-ground pool, a heat pump usually makes more sense when electrical heating is the goal because the heat pump moves existing heat from the air rather than relying entirely on resistance heating.
We would not choose a basic resistance heater for a large pool simply because the purchase price looks cheap.
Running cost matters too.
How Much Energy Does It Actually Take to Heat Your Pool?
This is where heater sizes start making much more sense.
One gallon of water weighs about 8.34 pounds, and one BTU raises one pound of water by approximately 1°F.
So the theoretical heat required is:
Pool gallons × 8.34 × desired temperature rise = BTUs required
For example, suppose you have a 5,000-gallon pool at 72°F and want it at 82°F.
That's a 10°F increase.
5,000 × 8.34 × 10 = 417,000 BTU
The water itself therefore needs roughly 417,000 BTU of heat for that 10°F rise.
That is before accounting for heat being lost to the air, evaporation, wind and cooler surroundings while you're heating.
What That Means for Heater Size
Using the same 5,000-gallon pool and ignoring heat loss for a moment:
These are theoretical best-case figures, not heating-time promises. Real heating normally takes longer because the pool is losing heat at the same time, and a heat pump's actual output can vary with outdoor conditions.
This calculation explains why an 18,000 BTU heater can be perfectly sensible for a smaller pool but feel very slow on a larger one.
Pool Heating Time Calculator
This calculator shows the theoretical minimum heating time based on pool volume, temperature increase and the heater's rated BTU output. Real heating usually takes longer because heat is being lost while the pool warms, and heat-pump output can vary with outdoor conditions.
Want to estimate what the heat pump could cost to run? Use our Heat Pump Running Cost Calculator to enter the heater's BTU output, COP, daily run time and your local electricity rate.
Work Out Your Pool Volume Before Choosing a Heater
Don't size a heater by pool diameter alone.
A 15-foot round pool filled to 36 inches contains far less water than another 15-foot pool filled much deeper.
Actual water volume matters because that is the amount of water you're trying to heat.
If you're not sure how many gallons your pool holds, use our Pool Volume Calculator for Above-Ground Pools before comparing heater sizes.
Then consider the temperature rise you actually want.
Taking a pool from 77°F to 82°F is a much easier job than taking it from 60°F to 82°F.
Don't Confuse Maximum Pool Size With Fast Heating
A manufacturer's maximum pool-size rating is not the same thing as a promise of fast heating.
If a manufacturer says:
“For pools up to 9,000 gallons”
that does not mean:
“This will heat a 9,000-gallon pool quickly.”
It means the manufacturer considers that pool volume within the unit's intended operating range.
Heating speed still depends on:
BTU output;
air temperature;
starting water temperature;
desired water temperature;
wind;
cover use;
and heat loss while the unit is running.
If you live in a cooler climate or want faster recovery, giving yourself more heating capacity can be useful.
The Cheapest Way to Heat an Above-Ground Pool
If your goal is spending as little as possible, we'd approach it in this order.
First, use a solar cover consistently.
Second, reduce avoidable heat loss from wind where practical.
Wind moving across the pool surface increases evaporation and carries heat away from the water. If your pool sits in an exposed yard, a suitable fence, privacy screen, hedge or other windbreak can help reduce that constant airflow.
Keep any barrier positioned so it does not interfere with safe access, visibility around the pool or required equipment clearances.
A solar cover combined with reduced wind exposure can make a noticeable difference to how much warmth the pool keeps overnight.
Third, take advantage of solar heating if your yard gets good direct sunlight.
Fourth, add powered heating when the passive options cannot deliver the water temperature or season length you want.
This is much more efficient than buying a heater first and then leaving the pool uncovered every night.
The Cheapest Setup Is Not Always the Cheapest Heater
An inexpensive heater that has to run constantly can cost more over time than a more efficient system.
Likewise, an expensive heat pump can be unnecessary if you have a small seasonal pool that only needs a few extra degrees during sunny weather.
Think in terms of:
purchase price + installation + running cost + how often you'll actually use it
rather than purchase price alone.
That's especially important with above-ground pools because the heater can sometimes cost as much as, or more than, the pool itself.
How to Keep an Above-Ground Pool Warm Overnight
If your pool feels good at 5 PM and cold the next morning, overnight heat retention should be your priority.
We would:
cover the water as soon as swimming is finished;
minimize unnecessary water features or aeration while trying to retain heat;
reduce wind exposure where practical;
keep the pool properly filled so circulation works normally;
and avoid unnecessarily reheating from a much lower temperature every morning.
A fountain may look great, but spraying warm pool water into cool evening air increases surface exposure and can accelerate heat loss.
The goal overnight is to keep as much stored heat in the water as possible.
Should You Leave a Solar Cover on During the Day?
If the pool isn't being used, a solar cover can often stay on during the day.
Direct sunlight can contribute useful warmth while the cover also reduces evaporation.
If you use solar heating mats, operate the circulation and solar system according to the manufacturer's instructions.
And remember that a solar cover is not a safety cover.
Never treat it as something that can support a person, child or pet.
Can You Heat an Intex or Bestway Above-Ground Pool?
Yes, many Intex, Bestway and similar frame pools can be heated.
The important question isn't simply the brand.
Check:
actual pool volume;
heater compatibility;
plumbing and hose size;
required water flow;
electrical supply;
maximum water-temperature guidance;
and manufacturer instructions.
Small plug-in heat pumps and solar mats can be convenient for common frame pools because many are designed around standard above-ground-pool connections.
Larger heaters may require adapters, larger plumbing, dedicated electrical circuits or a more involved installation.
What Is the Most Efficient Way to Heat an Above-Ground Pool?
For regular powered heating, we'd generally look at a correctly sized heat pump paired with a solar cover.
The heat pump moves heat from the air rather than producing all of it through electrical resistance, while the cover helps reduce avoidable heat loss at the water surface.
But “most efficient” does not automatically mean “best.”
If you want to swim tomorrow morning and the pool is 20°F too cold, a small efficient heat pump may not meet your timing.
In that situation, heating capacity and speed matter more.
Efficiency only helps if the system actually fits how you use the pool.
What Is the Fastest Way to Heat an Above-Ground Pool?
A properly sized gas or propane heater will generally provide much faster heating than a small above-ground-pool heat pump or solar mat.
That makes gas attractive for occasional heating and rapid recovery.
But don't buy based on BTU alone.
Gas supply, installation cost, local fuel price, plumbing and heater compatibility all need to work for your setup.
A fast heater also wastes money quickly if the pool remains uncovered.
What Is the Best Setup for Extending the Swimming Season?
If the goal is swimming earlier in spring and later into fall, we'd normally prefer:
a properly sized heat pump + solar cover
rather than relying on solar heating alone.
The solar cover reduces heat loss while the heat pump gives you a controllable source of heat when sunlight isn't enough.
For a small pool, the AquaStrong HEX018 may be sufficient.
For more heating capacity while retaining a 120V setup, the AquaStrong 35,000 BTU HEX035 provides a useful middle ground.
For a larger pool or stronger recovery, the AquaStrong 55,000 BTU HEX055 steps up to 220V and substantially more heating capacity.
If you're still comparing heater types rather than individual models, visit our Heat Pumps & Solar Covers guide.
A Simple Heating Strategy That Works for Most Above-Ground Pools
If we were trying to warm an above-ground pool without wasting money, we'd do it in this order:
1. Work out the actual pool volume.
2. Start retaining heat with a solar cover.
3. Decide how much warmer you actually want the water.
4. Decide whether you care more about lower running costs or fast heating.
5. Choose a heater with enough output for that pool and temperature rise.
6. Continue using the cover after the heater is installed.
That sequence prevents the common mistake of buying heating equipment before understanding the actual heating problem.
Our Final Take
There is no single cheapest or best way to heat every above-ground pool.
If you want the lowest-cost starting point, buy and consistently use a solar cover.
If you have a small sunny pool, a solar cover and solar heating mat may be enough.
If you want efficient powered heating and a longer swim season, a properly sized heat pump paired with a cover is the setup we'd look at first.
If you want fast heat on demand, gas or propane has the advantage in heating capacity, but installation and fuel costs matter.
Whatever heater you choose, don't ignore heat retention.
Putting thousands of BTUs into the pool while allowing evaporation and cool overnight air to remove them again is an expensive way to stay warm.
Start by understanding your pool volume, the temperature increase you actually want and how quickly you need it.
Then choose the heating method that fits those three things.
For specific heater and solar-cover recommendations, visit our Heat Pumps & Solar Covers section.
Frequently Asked Questions
What is the cheapest way to heat an above-ground pool?
A solar pool cover is usually the cheapest place to start because it reduces heat loss and evaporation without using fuel or electricity. For a small sunny pool, adding a solar heating mat can provide additional warmth without the running cost of a powered heater.
What is the most efficient way to heat an above-ground pool?
For regular powered heating, a correctly sized pool heat pump paired with a solar cover is usually one of the most efficient setups. The heat pump transfers heat from the air into the water, while the cover helps reduce heat loss from evaporation.
What is the fastest way to heat an above-ground pool?
A properly sized gas or propane pool heater will generally heat water faster than a small heat pump or solar heater because it can provide much higher BTU output. The trade-off is fuel cost and a more involved installation.
How long does it take to heat an above-ground pool?
Heating time depends on the pool's water volume, heater output, starting temperature, desired temperature, outdoor conditions and heat loss. As a theoretical example, raising 5,000 gallons by 10°F requires about 417,000 BTU before accounting for heat loss.
Does a solar cover actually heat an above-ground pool?
A solar cover can support warming from sunlight, but its biggest benefit is reducing evaporation and slowing heat loss. It is better thought of as a heat-retention tool than a replacement for a powered heater.
Can I use a heat pump on an above-ground pool?
Yes. Many heat pumps are specifically suitable for above-ground pools. Check the heater's pool-volume rating, BTU output, required water flow, hose or plumbing connections, electrical supply and operating-temperature range before choosing one.
Can you heat an Intex or Bestway pool?
Many Intex, Bestway and similar frame pools can be heated with compatible solar or powered heating systems. Check the pool manufacturer's instructions, actual water volume, plumbing size, required flow and the heater manufacturer's installation requirements.
Is a heat pump better than a gas pool heater?
A heat pump is generally better for efficient long-term temperature maintenance, while gas or propane is generally better when fast heat-up and quick recovery matter more. The better option depends on how often you heat the pool and how quickly you need the temperature to rise.
Should I use a solar cover with a pool heater?
Yes. A solar cover can reduce evaporation and slow overnight heat loss, which means your heater has less lost heat to replace. It is useful with heat pumps, gas heaters and solar heating systems.
What size pool heater do I need?
Start with your actual pool volume, desired temperature rise and climate rather than choosing only from a manufacturer's maximum gallon rating. Larger pools, colder conditions, windy locations and faster heat-up expectations generally require more heating capacity.
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