Types of Pool Heaters
(Pros, Cons, And How
to Choose the Right One)

Not all pool heaters are created equal. Some types of pool heaters deliver speed. Others focus on long-term savings. A few offer convenience and comfort with minimal effort. The key is knowing which one fits your pool, your lifestyle, and your expectations.

Why choosing the right pool heater matters

Buying the wrong pool heater is like putting racing tires on a family minivan. It may function, but it’s not efficient or practical.

A poorly matched heater can leave you paying high energy bills, waiting hours for your pool to warm up, or skipping swims because the system isn’t delivering what you expected. On the other hand, the right pool heating solution can make ownership feel seamless. It works with your schedule, your climate, and your habits. You get more value from your investment and more comfort from your pool.

This guide explains how different types of pool heaters work, compares major options, and shows you how to make a smart, confidence-backed decision.

Not sure if you even need a pool heater yet?

Start here: How to Heat Your Pool

What is a pool heater, really?

A pool heater is a device that warms your water so you can swim comfortably regardless of weather or time of year. Whether you’re trying to stretch the season or enjoy a hot spa, your system directly affects how often you actually use your pool.

All pool heaters connect with your existing pool’s plumbing after the pump and filter. As water circulates, it picks up heat inside the heater unit and returns to your pool. That heat might come from gas combustion, electric resistance, solar energy, or the ambient air.

What matters most is how quickly and efficiently that energy transfers into your pool. If you have an inground pool, choosing the right type of heater becomes even more important. Heating a larger body of water takes real performance.

What are BTUs, and why do they matter?

Heater performance is measured in BTUs, or British Thermal Units. One BTU increases the temperature of one pound of water by one degree Fahrenheit. When you’re heating tens of thousands of gallons, that number becomes crucial.

Think of BTUs like horsepower in a vehicle. A four-cylinder engine can pull a trailer, but a V8 does it faster and with less strain. More BTUs means quicker warm-ups and better handling of heat loss overnight.

How does a pool heater work?

All pool heaters rely on your pump to circulate water through a heating unit and back into the pool through the return lines. This closed-loop system ensures all the water is gradually brought up to your desired temperature.

The primary difference between how each pool heater works is the method used to generate that heat.

• Gas Heaters burn natural gas or propane to create intense heat quickly (best for raw speed).
• Heat Pumps pull ambient heat from the surrounding air and transfer it to the water (best for high efficiency).
• Solar Systems circulate water through panels that absorb the sun's natural energy (best for zero operating cost).
• Heat Pump/Chiller Combos can either heat or cool the water, offering total temperature control (best for all-season flexibility).

No matter what system you choose, the quality of your pump, plumbing, and insulation plays a big role in how a pool heater works. Matching the heater type to your pool’s size and layout makes a noticeable difference.

What’s the best pool heater for your pool type?

While your personal priorities are key, the physical type of your pool provides a clear starting point for choosing a heater. Here’s a straightforward breakdown of the best-fit heaters for each setup.

For Inground Pools

The Challenge

Large water volume requires a powerful and efficient heating solution to keep seasonal costs from becoming overwhelming.

Primary Recommendation: Heat Pump Heater

An inground pool is a long-term investment, and a heat pump’s incredible energy efficiency aligns perfectly with that. For a typical swim season (Memorial Day to Labor Day), a heat pump will maintain a comfortable temperature at the lowest possible operating cost.

Best for Colder Climates (like Pennsylvania): Gas Heater

If you want to stretch your season into late April, May, or into October when evening temperatures drop below 50°F, a gas heater is your most reliable option. A heat pump will struggle or stop working in those conditions, but a gas heater can deliver powerful heat regardless of the air temperature.

The Verdict

For most of the swim season, a heat pump is the most economical choice. If you're a serious swimmer who wants to maximize every possible day in the water, a gas heater (or a hybrid system) is a necessity.

For Above-Ground Pools

The Challenge

Above-ground pools lose heat much faster through their exposed side walls, making efficiency paramount to avoid "heating the neighborhood."

Primary Recommendation: Heat Pump (specifically models for above-ground pools)

To combat the rapid heat loss, you need a heater that's cheap to run for longer periods. Heat pumps are perfect for this. Many brands offer smaller, more affordable models (typically under 75,000 BTUs) designed specifically for the water volumes of above-ground pools.

Budget-Friendly Alternative: Solar Heater

For owners in very sunny locations, a simple solar heating system can effectively raise the water temperature by 5-10 degrees with zero operating cost. It won't work on cloudy days, but it's a fantastic, low-cost way to make the water more comfortable.

The Verdict

Efficiency is king. A right-sized heat pump provides the most consistent and reliable comfort.

For Pool & Spa Combinations

The Challenge

You have two completely different needs: slow and efficient heating for the large pool, and rapid, high-temperature heating for the small spa.

Primary Recommendation: Hybrid System (Heat Pump + Gas Heater)

This is the no-compromise solution. You use the heat pump as your primary workhorse, efficiently keeping the pool warm all season. When you want to use the spa, you fire up the gas heater, which can take it from pool temperature to a hot 104°F in under an hour. You get the best of both worlds: efficiency and on-demand power.

Alternative: Large Gas Heater

A single, powerful gas heater (400k BTU) can handle both the pool and spa. While simpler to install, be prepared for significantly higher monthly fuel bills when using it to maintain the pool's temperature over the entire season.

The Verdict

A hybrid system perfectly matches the dual demands of a pool/spa combo and is the most cost-effective solution long-term.

For Indoor Pools, Spas, or Small Plunge Pools

The Challenge

Small water volume and a controlled indoor environment mean heat loss is minimal.

Primary Recommendation: Electric Resistance Heater

This is where electric resistance heaters shine. Their biggest drawback—high operating cost—is minimized because they only need to run for short periods to heat the small, well-insulated body of water. Their compact size, low upfront cost, and simple installation make them the most practical choic

The Verdict

For small, indoor, or specialty applications, the simplicity and low purchase price of an electric resistance heater make it the clear winner.

Choosing the best way to heat your pool isn’t just about BTUs or efficiency charts. It’s about knowing how you actually use your pool and what kind of experience you want every time you step in.

Explore All Pool Heater Options

Modern Pool Heaters: Smarter, Stronger, and More Efficient

Today's pool heaters are designed to be more intuitive, durable, and efficient than ever before, giving you precise control with less guesswork. If you’ve ever wished your pool could “just be ready,” these modern features are designed to make that a reality.

Control Your Pool Heater Remotely

Modern pool heaters put total control at your fingertips. With smartphone apps and remote controls, you can adjust the temperature, set schedules, and monitor energy usage from anywhere. This works hand-in-hand with digital thermostats that hold the water at a precise temperature, eliminating the need for daily manual tweaks. You can even set timers to align heating cycles with your swimming habits or off-peak energy rates, ensuring the pool is perfect when you need it and saving money when you don't.

Durability and Safety

A quality heater is built to last and operate safely. For pools with saltwater systems, a titanium heat exchanger is essential to prevent corrosion and extend the unit's lifespan. Furthermore, critical safety features like built-in flow switches and automatic shut-offs protect your investment by preventing the heater from running when water isn't circulating properly, which could otherwise cause serious damage.

Quiet, Ultra-Efficient Performance

Beyond smart controls, modern heaters are engineered for quiet comfort and peak efficiency. Heat pumps, in particular, feature insulated compressor compartments that make them neighbor-friendly.

To truly maximize performance, the ultimate pairing is a heater with a variable-speed pump (VSP). Heat pumps deliver their best results with long, steady periods of water circulation. A VSP is the perfect partner because it can run for many hours at a low, energy-sipping speed. This gives your heater the consistent flow it needs to work its magic without sending your electricity bill soaring, making it the key to unlocking maximum efficiency and comfort.

Are pool heaters worth it?

In short, the answer is yes. But deciding if a pool heater is worth it comes down to how you view the investment. In order for a pool heater to be worth it, you have to believe this isn't just about the equipment; it's about transforming your pool from a part-time attraction into the consistent centerpiece of your backyard.

A heater means extending your swim season by months, enjoying spontaneous evening dips without a shiver, and knowing your pool is always ready for family and friends. To truly determine if a pool heater is worth it for you, you have to look beyond the initial price tag.

Understanding the Total Cost of Ownership

The initial sticker price is only part of the story. A gas heater is often less expensive to buy, but its higher monthly running costs can add up quickly. On the other hand, heat pumps and solar heaters typically have a higher upfront cost but deliver significant long-term savings on your energy bills, often paying for themselves in just a few seasons. Ultimately, a well-chosen heater should feel like a seamless upgrade, quietly keeping the water perfect without adding stress to your budget.

Who Benefits Most from a Heater?

A pool heater is a game-changer for certain lifestyles. It's almost always a worthwhile investment for people who:

• Want to extend their swim season into the cooler months of spring and fall.
• Have an attached spa that needs to get hot on demand.
• Are families with kids or older adults who are more sensitive to colder water.
• Simply want the comfort and convenience of a consistently warm and ready-to-use pool.

Pro Tip: Protect Your Investment with a Pool Cover

The single biggest cause of heat loss in a pool is evaporation. Leaving your pool uncovered is like leaving a window open in winter while the heat is on. To get the most out of any heater and dramatically cut down on energy waste, use a pool cover. Whether it’s a physical solar blanket you roll out or a simple-to-use liquid pool cover, preventing evaporation will keep the warmth in the water, reduce your heater’s runtime, and save you money.

How to choose the right pool heater for you

Choosing the right pool heater isn’t just about buying a piece of equipment; it’s about defining how you want to use your pool. Now that you understand the technology, let’s walk through the final steps to find the perfect match for your backyard.

Step 1: Define Your Primary Goal

First, answer this one critical question: What is the single most important outcome you want from a heater? Your answer will point you directly to your best option.

I want my pool or spa hot right now.

Your priority is speed. You use your pool or spa intermittently and want on-demand heat for weekend parties or spontaneous evening soaks.

• Your Best Match: A Gas Pool Heater. Nothing beats its raw heating power, especially for spas.

I want to keep my pool comfortably warm all season long without a shocking energy bill.

Your priority is efficiency and low running cost. You are a daily or frequent swimmer and want to maintain a consistent temperature for months.

• Your Best Match: A Heat Pump Pool Heater. Its incredible efficiency makes it the champion of long-term, consistent heating in climates where temperatures stay above 50°F.

I want the lowest possible operating cost and have an environmental focus.

Your priority is sustainability. You live in a very sunny climate and want to supplement your pool's temperature during the warmest parts of the day and season.

• Your Best Match: A Solar Heating System. The upfront cost is offset by years of free energy from the sun.

Step 2: Consider Your Climate and Pool Setup

Your environment plays a huge role. An inground pool in Maine has very different needs than an above-ground pool in Arizona.

For Colder Climates or Year-Round Spa Use

A gas heater is the only option that works reliably when air temperatures drop near freezing.

For Mild to Hot Climates

A heat pump is the most economical and popular choice. If your pool gets too warm in the summer, a Heat Pump/Chiller Combo offers ultimate year-round temperature control.

For Pools with an Attached Spa

You have two distinct needs: slow, efficient heating for the pool and rapid, high-temperature heating for the spa. This is the perfect scenario for a hybrid heating setup. Use a heat pump for day-to-day pool maintenance and a gas heater to get the spa bubbling in minutes. It’s the ultimate combination of efficiency and on-demand power.

Step 3: Calculate the Correct Size (BTUs)

Don't guess your BTU needs. An undersized heater will run constantly without ever reaching your target temperature, while an oversized one is an unnecessary expense. Sizing depends on:

Pool Surface Area

The bigger the pool, the more heat it loses.

Desired Temperature Rise

The difference between your unheated pool water and your dream temperature.

Climate

The coldest average temperature during your swim season.

Environmental Factors

Wind exposure, humidity, and cool nights.

Recommendation

Use an online sizing calculator as a starting point, but always consult with a pool professional. They can perform an accurate heat-loss analysis to ensure you invest in a heater that performs perfectly without wasting energy.

Final thoughts

A pool heater shouldn’t be an afterthought. It should be a tool that helps you use your pool more often and more comfortably.

From gas to solar to smart-enabled heat pumps, the best heater is the one that aligns with your goals, your habits, and your climate. When you choose the right system, it’s like upgrading your pool from something you use occasionally to something that’s always ready.

Read next: How to Heat a Pool