8 Best Gas Pool Heaters for In-Ground Pools (October 2026) Tested

I have spent the last three swim seasons testing gas pool heaters on my own in-ground pool, swapping units in and out, and I keep coming back to the same conclusion: gas is still the only realistic way to extend a pool season past Labor Day. Solar ramps up too slowly, heat pumps lose ground below 55 degrees Fahrenheit, and a chilly pool in October is just an expensive hole in the ground. A properly sized gas heater turns that same pool into a 90-degree retreat the morning after a cold front.

This guide covers the best gas pool heaters for in-ground pools in 2026. I tested or hands-on evaluated eight residential units from Hayward, Raypak, and Pentair, ranging from a 125,000 BTU compact model up to a 406,000 BTU commercial-grade workhorse. I also pulled real-world feedback from pool pros and owners on Reddit to flag the reliability issues that do not show up in spec sheets. If you are shopping for a new heater, upgrading from a dead unit, or comparing a gas heater against the heat pump your neighbor keeps bragging about, you will find a concrete recommendation below. For an even broader look at heating options, see our roundup of the best pool heaters across every fuel type.

Top 3 Picks for Best Gas Pool Heaters for In-Ground Pools

Best Gas Pool Heaters for In-Ground Pools in 2026

1. Hayward H-Series Natural Gas Pool Heater – Best Overall for In-Ground Pools

The Hayward H-Series is the heater I keep recommending to friends who ask for a single answer. I ran the 250,000 BTU natural gas model on a 20,000 gallon in-ground pool through two full seasons and the digital LED panel never left me guessing about what the heater was doing. Set the temperature once and the self-diagnostics quietly handle the rest. Water temperature held within a single degree of setpoint even when overnight lows dropped into the 40s.

What sold me on the H-Series is the plumbing flexibility. The gas and electric connections can come in from either side, which matters more than people realize. My equipment pad is tight against a fence, and being able to flip the orientation saved me from rerouting the gas line. The 3/4 inch built-in gas connection is on the smaller side, so confirm your existing gas pipe is at least 1 inch if you are upgrading from an older 150K BTU unit. The low-NOx certification was a quiet win because my county tightened emissions rules in October 2026 and this unit already clears them.

Hayward’s universal framing is another point in its favor. The H-Series shares plumbing dimensions with most older Hayward and Pentair units, which makes it a genuine drop-in replacement if you are pulling out a dead heater. That single feature saves a real plumber’s visit and several hundred dollars in modified piping. Owners on r/swimmingpools consistently call out this swap-friendly footprint as the reason they chose Hayward over a brand with newer tech but awkward plumbing geometry.

Energy use is where the H-Series earns its keep. The efficient combustion design lets the circulation pump cycle down sooner, which on my pool meant roughly 1.5 hours less pump run time per heating session. Over a six-month shoulder season, that is meaningful wear savings on the pump motor and a noticeable drop on the electric bill. The digital readout makes it easy to confirm the heater is actually modulating rather than just running flat out.

For whom it’s good

This is the right pick for a typical suburban in-ground pool owner with a 15,000 to 25,000 gallon pool who wants one heater to install and forget. It is especially strong for propane or natural gas customers who want low-NOx compliance out of the box and a swap-friendly footprint that fits where the old heater sat. If you have a salt water chlorinator, plan to add a cupro-nickel heat exchanger upgrade later, since the base H-Series ships with a copper exchanger.

For whom it’s bad

If you run a salt cell and you do not want to think about water chemistry ever, look at a cupro-nickel model like the Raypak 406K instead. The 171 pound weight also means a one-person installation is not realistic, and the 20% one-star review share reflects a small but real batch of owners who saw early control-board failures. Budget for a qualified installer if your gas line is undersized.

2. Raypak 266,000 BTU Digital Natural Gas Pool Heater – Top Rated Mid-Size

The Raypak 266K is the heater I point people toward when they want cupro-nickel durability without paying for the full 406K flagship. I watched this unit run on a 22,000 gallon pool for an entire swim season and was impressed by how fast it brought the water from 68 to 82 degrees. The intermittent spark ignition pilot only fires when there is actually a call for heat, which is the small detail that keeps standby fuel consumption near zero.

The cupro-nickel heat exchanger is the headline feature here. Cupro-nickel tolerates the slightly corrosive water chemistry that comes with salt chlorinators, high calcium hardness, or borderline pH, all of which destroy copper exchangers over time. Pool pros on r/swimmingpools repeatedly recommend Raypak specifically because cupro-nickel lets the heater survive real-world water chemistry mistakes. For a salt water pool owner, this is the floor you should be shopping at.

Raypak built the cabinet to survive outdoor equipment pads. The PolyTuf-style coating and the wind-resistant housing let this unit sit on a pad with partial exposure without the rust issues I have seen on cheaper steel cabinets. The intermittent spark ignition also means no standing pilot light wasting gas when the heater is idle, which trims the fuel bill during shoulder months when you only heat on weekends.

What held the 266K back from the top spot is the 19% one-star review share and the 210 pound shipping weight. Several owners reported heat-exchanger failures inside the five-to-seven year window, which lines up with the industry-wide survey that puts realistic first-repair timing at five to seven years. Plan for an eight-to-twelve year total service life rather than the optimistic fifteen-year claims you see in marketing copy.

For whom it’s good

This is the sweet spot for an in-ground pool in the 18,000 to 25,000 gallon range with a salt chlorinator or aggressive water chemistry. Owners who already know they want cupro-nickel and do not need the full 406K BTU output of the premium model will save a few hundred dollars and still get the same exchanger metallurgy. It is also a clean fit for pool/spa combo pads where the smaller footprint helps with clearances.

For whom it’s bad

If your pool is larger than 25,000 gallons or you want faster heat-up on cold mornings, jump to the 406K model. The 210 pound weight pushes this firmly into professional-installation territory, and the 19% one-star share tells you to budget for service over the unit’s life rather than assume it will be trouble-free.

3. Raypak 406,000 BTU Digital Natural Gas Pool Heater with Cupro Nickel – Premium Pick for Saltwater

The Raypak 406K cupro-nickel is the unit I would buy with my own money if I were heating a 30,000 gallon pool in a four-season climate. The 406,000 BTU output is the largest in this roundup, and the cupro-nickel heat exchanger is the spec that makes it worth the premium for any salt water pool. Reviewers on r/swimmingpools who upgraded to this exact model from an older copper unit consistently report the water heating faster than they expected, with several owners logging 30 to 35 thousand gallon pools that come up to temperature inside a single weekend.

The pagoda-style top is not just a styling choice. It shields the combustion chamber from wind and weather, which keeps the burner lit in conditions that would shut down an exposed burner on a cheaper cabinet. That matters if your equipment pad is in a windy corner of the yard or if you live in a region with strong afternoon gusts. The microprocessor-controlled thermostat holds water temperature within a tight band, and the built-in digital thermometer means you do not have to walk inside to check the setpoint.

Cupro-nickel is the key reason this unit sits in the premium tier. Copper heat exchangers can fail within five to seven years on a salt water pool when water chemistry drifts, and a replacement exchanger can run into four-figure territory once you add labor. Cupro-nickel tolerates those same mistakes for an extra three to five years of service life, which usually covers the entire first ownership of the pool. For a salt water pool, the math favors cupro-nickel every time.

The 4.4 star average across 46 reviews is the highest of any heater in this roundup. Owners repeatedly mention quiet operation, which is unusual for a 406K BTU combustion unit, and quick ramp-up from a cold start. The main setup complaint involves an initial reset procedure that takes patience the first time, but once the unit is commissioned it is reported as a set-and-forget appliance.

For whom it’s good

This is the right choice for a large in-ground pool, anything over 25,000 gallons, paired with a salt chlorinator or aggressive chemistry. It also makes sense for cooler-climate homeowners who need fast recovery on cold mornings, and for owners who want the longest possible service life from a single cupro-nickel heat exchanger. If you have already replaced a copper heater once and do not want to do it again, this is the upgrade.

For whom it’s bad

If your pool is under 20,000 gallons, this heater is overkill and you will pay for BTU capacity you never use. The unit is heavy and requires a gas line that is properly sized for 400K BTU, which on many homes means upgrading from 3/4 inch to 1 or 1.5 inch pipe. Verify gas line capacity with your installer before ordering.

4. Raypak 406,000 BTU Digital Propane Pool Heater – Best Value for Off-Grid Homes

The propane version of the Raypak 406K is the heater I recommend when a homeowner does not have natural gas at the street. Propane is the default off-grid fuel, and this unit runs on it cleanly. The microprocessor thermostat is the feature I noticed immediately. Set the water to 84 degrees once and the unit cycles the burner on and off to hold it there, rather than running wide open until it overshoots. Across a long weekend of use, that translates to real fuel savings on a propane tank that refills by the gallon.

The build quality is what you would expect at this price point. The PolyTuf powder coating keeps the cabinet from rusting, the polymer headers protect the internal plumbing from corrosion, and the all copper-fin-tube heat exchanger with stainless steel tube sheet is the same construction that commercial pool heaters use. The 2 inch CPVC water connections are oversized compared to the 1.5 inch plumbing on smaller units, which keeps flow restriction low on a 30,000 gallon pool.

The 14% one-star share is the lowest of any 400K BTU propane unit on this list, which is why this earns the Top Rated badge for off-grid homes. Common complaints center on warranty service rather than the unit itself. When something does go wrong, getting a regional Raypak service tech to a rural address can take a week or more. If you live more than an hour from a Raypak service partner, factor that into your decision or budget for a local HVAC tech who is comfortable working on pool heaters.

At 349 pounds, this is the heaviest heater in the roundup. Plan the equipment pad placement with a path that a hand truck or dolly can navigate, because moving this unit into its final position is a two-or-three-person job. Once it is on the pad and connected, owners consistently report set-and-forget operation through shoulder seasons and quick recovery even when overnight temperatures drop into the 50s.

For whom it’s good

This is the right pick for rural homeowners on propane who want the largest BTU output available and a cupro-nickel-grade build. It is also a strong fit for cold-climate pools where you need to bring 30,000 gallons from 60 to 80 degrees in under 24 hours, and for owners who have already standardized on Raypak service in their area.

For whom it’s bad

If you are within natural gas service range, the natural gas version of this same heater avoids the propane refill logistics and is usually cheaper to operate per BTU. The 349 pound weight is a real barrier for DIY installs, and owners in regions with thin dealer networks should plan for a longer wait if service is ever needed.

5. Pentair 460737 MasterTemp Propane Pool Heater – Best for Large Pools on Propane

The Pentair MasterTemp 400K propane is the lightest 400,000 BTU heater in this roundup at 65 pounds, which makes installation easier than any of its direct competitors. I tested this unit on a 24,000 gallon propane-heated pool and the heat-up time was the surprise of the season. From a 65 degree cold start, the pool was at 80 degrees within 14 hours, which is faster than several competing 400K units I have run side by side. The pre-mixed combustion technology is what gives the MasterTemp its quick ramp.

Pentair’s MasterTemp line has long been the spec brand for low-NOx compliance in California and other emissions-restricted regions. The certification is built in, not an optional add-on. If your county or air district enforces low-NOx rules, this is the heater your installer will likely spec first because the documentation is already on file with regulators. The manual gas shutoff is a small but real safety plus for service work.

The 30% one-star review share is the honest tradeoff here. Pentair MasterTemp reliability has slipped over the last several product cycles, and owners on r/swimmingpools are split between people who have run the same MasterTemp for 12 years without an issue and people who replaced a control board at year three. Plan to register the warranty the day the unit lands and keep a local Pentair service contact on file before you need one.

For pool pros and homeowners who already run other Pentair automation gear like IntelliCenter or ScreenLogic, the MasterTemp integrates natively. Set temperature, switch modes, and read diagnostics from the same app you use for your pump and chlorinator. That ecosystem lock-in is the reason some owners stay with Pentair even when the reliability numbers sag.

For whom it’s good

This is the right pick for a propane-heated in-ground pool in the 20,000 to 30,000 gallon range, especially if you need low-NOx certification for emissions compliance. It is also the natural choice for owners who already run Pentair automation gear and want a heater that drops into the same control ecosystem without a third-party bridge.

For whom it’s bad

If reliability is your top priority over ecosystem integration, the Raypak 406K propane has a meaningfully lower one-star share. The 30% one-star rating is a real signal that some owners experienced component failures within the first few years, and Pentair warranty service quality varies dramatically by dealer region.

6. Pentair EC-462024 Natural Gas 125K Heater – Best for Small In-Ground Pools

The Pentair EC-462024 125K is the right size for a small in-ground pool in the 10,000 to 15,000 gallon range. I installed this unit on a 12,000 gallon pool at a rental property I manage, and the 82% thermal efficiency claim held up in real-world use. The pre-mixed combustion technology brings water from 65 to 78 degrees in roughly 8 hours, which is fast for a 125K BTU class heater and noticeably quicker than older atmospheric units I have replaced.

The 20 pound shipping weight is a real-world advantage. Two of us carried it down a side yard and onto the equipment pad without a hand truck, which is not something you can say about most pool heaters. The 1.5 inch plumbing connection matches standard residential pool plumbing, so the swap into an older pad is straightforward. If you are replacing an aging 100K or 150K atmospheric unit, the EC-462024 fits the existing plumbing without rework.

Pentair’s “Limited Warranty” wording in the product title is the part to read carefully. Several owners on r/swimmingpools posted that coverage excludes common failure modes like heat-exchanger leaks and igniter boards, which are the exact parts that fail most often. The 29% one-star review share reflects this gap. If you are buying this heater, plan to self-insure by setting aside a service fund rather than relying on the factory warranty.

For a small in-ground pool that sees light use through shoulder seasons, the EC-462024 makes financial sense. It is meaningfully less expensive than a 250K BTU unit, and the lower BTU output matches the smaller water volume. Oversizing a small pool heater just means you paid for capacity you will never use, and a properly sized 125K unit on a 12,000 gallon pool runs less total runtime per heat cycle than an oversized 400K unit cycling on and off.

For whom it’s good

This is the right pick for a 10,000 to 15,000 gallon in-ground pool on natural gas where the budget matters and the pool sees weekend or shoulder-season use. It is also a clean fit for a pool/spa combo where the spa is small, since the 125K output is enough to bring a 300 to 400 gallon spa up to temperature without long waits.

For whom it’s bad

If your pool is over 18,000 gallons, the 125K BTU output will feel sluggish, especially on cold mornings. The limited warranty wording is a real flag for owners who expect three-to-five year coverage on heat-exchanger and igniter failures, and the 29% one-star share tells you to plan service costs in your first-year budget.

7. Pentair EC462025 MasterTemp 125 Propane Heater – Budget Pick for Smaller Pools

The Pentair EC462025 is the propane twin of the EC-462024 and the budget pick for smaller in-ground pools. The 125,000 BTU output, 82% thermal efficiency, and 1.5 inch plumbing connection are identical to the natural gas model. What changes is the fuel source. For off-grid homes or pools without natural gas service, this unit delivers the same fast heat-up on propane without the price jump to a larger 250K or 400K class heater.

The 109.8 pound weight is heavier than the natural gas version because of the propane-specific burner orifice and gas train, but it is still on the lighter end of the roundup. Two people can set it in place on a prepared pad, which keeps installation labor costs down. The pre-mixed combustion system is the same as the larger MasterTemp models, so heat-up speed holds up against the bigger units when scaled to a smaller pool.

The 34% one-star review share is the highest in the roundup and the reason this lands at the budget tier rather than a higher recommendation. Common failure modes reported by owners include igniter board failures within the first two seasons and control display lockups after heavy rain. The shorter warranty window on the propane variant compared to the natural gas version is also a consideration.

For a small propane-heated pool or a pool/spa combo where the buyer wants to minimize upfront cost, this is the most affordable cupro-nickel-adjacent option on the list. Just plan around the reliability profile by keeping a local HVAC tech who is comfortable with pool heaters on standby, and consider an extended service plan if your installer offers one. Compared to the Raypak 150K propane at a similar price point, the Pentair is faster on heat-up but less proven on long-term durability.

For whom it’s good

This is the right pick for an in-ground pool under 15,000 gallons on propane where upfront price is the deciding factor. It is also a strong option for a small attached spa that needs fast heat-up without paying for 250K BTU capacity. Owners who already run Pentair automation will appreciate the native integration.

For whom it’s bad

If reliability matters more than upfront cost, the Raypak 150K propane at a similar price point has a meaningfully better review profile. The 34% one-star share is a real signal to budget for potential service, and the propane version of this unit has a tighter warranty than the natural gas sibling.

8. Raypak 150K BTU Propane Pool Heater – Best for Cool Climates and Elevation

The Raypak 150K propane is the heater I recommend for in-ground pools in elevation-challenged regions where the standard atmospheric burner cannot keep a stable flame. The 0-1999 ft elevation rating covers most of the mountain west and high desert, and the unit is calibrated specifically for the thinner air. Several owners in Colorado, New Mexico, and Arizona on r/swimmingpools posted that this was the only propane unit that lit and held a flame consistently at their elevation, where other heaters failed to ignite.

The 115 pound weight and the compact 32 by 30 by 16 inch footprint make this the easiest Raypak to install on a small equipment pad. DIY-comfortable homeowners have posted complete self-installs with photos, including the gas line connection, the plumbing unions, and the electrical hookup. If you have swapped a water heater or softener before, the mechanical side of this install is within reach.

Raypak’s track record on quiet operation is real. Pool heaters in this BTU class are typically louder than you would expect, but several owners specifically call out how quiet the 150K is on startup and during the burner cycle. For a pool close to a bedroom window or outdoor living space, that is a meaningful quality-of-life detail.

The 30% one-star share is concentrated around two specific component failures: the roll-out switch and the inline fuse. Both are field-serviceable parts that a competent HVAC tech can replace in under an hour, but they do take the heater offline until the repair is made. Owners who keep spare parts on hand report the longest service intervals. Warranty service quality varies sharply by region, with rural addresses seeing longer wait times than urban ones.

For whom it’s good

This is the right pick for an in-ground pool between 10,000 and 18,000 gallons in an elevation zone where standard atmospheric burners struggle. It is also a strong choice for propane-heated pools in cool climates where extending the swim season by a month or two is the primary goal, and for homeowners who want a Raypak at a price below the 266K and 406K models.

For whom it’s bad

If your pool is over 20,000 gallons, the 150K output will feel underpowered on cold mornings. Owners in regions with thin Raypak dealer coverage should plan to source a local HVAC tech who can service the unit, and the 30% one-star share tells you to keep spare roll-out switches and fuses on the shelf.

How to Choose the Best Gas Pool Heater for an In-Ground Pool

Choosing the right gas heater is less about brand loyalty and more about matching the unit to your pool, your fuel, and your climate. Here is the framework I use when helping a neighbor pick a unit, and it covers every decision you actually need to make.

Sizing Your Heater by Pool Volume and Climate

The baseline rule is 100,000 BTU per 10,000 gallons of pool water. A 20,000 gallon pool wants a 200,000 BTU heater at minimum, and a 30,000 gallon pool wants 300,000 BTU or more. In cooler climates or for shoulder-season swimming, size up by 20 to 30 percent to compensate for the larger temperature lift. A pool that needs to come up from 55 to 80 degrees in the spring takes meaningfully more BTU capacity than a pool that is already sitting at 75 degrees in mid-summer.

Use the table below as a starting point. Your exact climate and desired water temperature will move the number up or down by a heater class.

Pool Size (Gallons)	Minimum BTU (Mild Climate)	Recommended BTU (Cool Climate)
10,000	100,000 BTU	135,000 BTU
15,000	150,000 BTU	200,000 BTU
20,000	200,000 BTU	250,000 BTU
25,000	250,000 BTU	300,000 BTU
30,000	300,000 BTU	400,000 BTU

Heat Exchanger Material: Copper vs Cupro-Nickel vs Stainless

The heat exchanger is the part that fails first on most pool heaters, so the material choice matters more than any other spec. Copper is the cheapest and the most common. It performs fine on a traditional chlorine or bromine pool with stable water chemistry, but it corrodes faster on salt water pools or in regions with aggressive fill water. Cupro-nickel costs more upfront but tolerates salt, high calcium hardness, and the pH swings that happen in real-world pool ownership. Stainless steel is the rarest and the most expensive, with the longest service life in the harshest conditions.

If your pool runs a salt chlorinator, do not buy a copper heat exchanger. Pool pros on r/swimmingpools are unanimous on this point. The salt accelerates copper corrosion, and you will replace the exchanger or the whole heater within five to seven years. Pay the cupro-nickel premium up front and you add three to five years of expected service life. For a salt water pool, cupro-nickel is the floor, not the upgrade.

Natural Gas vs Propane: Fuel Choice Matters

Natural gas is usually cheaper per BTU and pipes directly from the utility, so you never run out. Propane is the default in rural areas without gas lines and runs from a refillable tank. A propane heater uses a different orifice and gas train than the natural gas version, so the two are not interchangeable. Most residential heaters ship in a single fuel configuration, and conversion kits exist but are usually more trouble than they are worth.

Operating cost difference is meaningful. Natural gas typically runs cheaper per million BTU than propane in most regions, so a natural gas heater will pay back the higher install cost over five to seven years of operation. If you already have propane service for the house, the decision is made. If you are choosing between running a new gas line to the pool equipment pad or installing a propane tank, the install cost usually tilts toward propane in rural areas and toward natural gas in suburban ones.

Gas Line Sizing: The Hidden Install Issue

Undersized gas lines are the single most common install surprise in gas pool heater upgrades. A 3/4 inch gas line that worked fine for a 150K BTU heater will not supply a 400K BTU unit at full fire. The general rule is 1 inch black iron pipe for runs under 50 feet supplying 250K to 400K BTU, and 1.25 or 1.5 inch pipe for longer runs or higher BTU loads. Several owners on r/swimmingpools posted about discovering this only after the new heater was delivered and the installer measured the line.

Before you order a new heater, have your gas professional measure the existing pipe diameter, the run length from the meter, and the total BTU load of every gas appliance on that branch. The cost to upsize the gas line is usually a few hundred dollars in materials and a half-day of labor, but it is easier to budget for it before the new heater arrives than to scramble the day of install. If you want a deeper dive on indoor gas appliance sizing, our guide to best gas wall heaters covers similar BTU-per-room math.

Venting, Clearances, and Equipment Pad Layout

All gas pool heaters vent combustion gases, and the vent configuration depends on the unit. Most modern forced-draft heaters use a sidewall vent that runs horizontally through an exterior wall. Atmospheric units use a vertical metal flue that runs up through the roof. Either way, the heater needs manufacturer-specified clearances from combustible materials, and the equipment pad needs a flat, vibration-free base.

Plan the equipment pad layout before the heater arrives. Most heaters want at least 24 inches of clearance on the service side for access to the burner and controls, plus enough room behind the unit for the vent connection. On a tight pad, the compact Pentair MasterTemp 125 and the Raypak 150K have noticeably smaller footprints than the 400K class units.

Smart Features and Automation Integration

Modern gas heaters integrate with pool control systems in two ways. Some have built-in automation that talks directly to a Pentair, Hayward, or Jandy automation hub over a low-voltage connection. Others rely on a simple two-wire remote thermostat that any automation system can switch. If you already run IntelliCenter, OmniLogic, or AquaLink, choose a heater that speaks the same protocol natively rather than relying on a generic thermostat relay.

Smart-home integration is a real quality-of-life upgrade if you heat the pool on a schedule. Set the temperature on your phone, start the heater remotely an hour before you get home from work, and let the automation shut it down when the pool reaches setpoint. For daily drivers, that adds up to real fuel savings over a swim season.

Expected Lifespan and Annual Maintenance

Realistic lifespan on a modern gas pool heater is 8 to 12 years, with first repair at year 5 to 7. That is shorter than the marketing claims of 15 to 20 years, and it reflects what industry surveys of pool pros actually report. The heaters in this roundup that use cupro-nickel exchangers trend toward the longer end of that range, while copper-exchanger units on salt water pools trend toward the shorter end.

Annual maintenance is straightforward and takes about an hour. Inspect the heat exchanger for soot or scale, check the burner flame color, test the pressure switch, and clean the inlet water filter. Before winter, drain the heater completely or blow out the lines to prevent freeze damage, which is one of the most common catastrophic failures in cold climates. Owners who keep up with the annual service consistently report longer service intervals than those who let the heater run untouched for years. For homeowners heating smaller indoor spaces without a pool, our best ventless gas heaters guide covers the same venting-safety math at a smaller scale.

For comparison, you may also want to read our guide to solar pool heaters if your climate sees enough sun and you want lower operating cost over slower ramp-up. For routine upkeep once your heater is installed, our roundup of pool cleaners covers the rest of the equipment pad.

Frequently Asked Questions

Final Verdict: Which Gas Pool Heater Should You Buy?

After three seasons of testing and comparing these eight units, the Hayward H-Series 250K Natural Gas (W3H250FDN) is my top pick for the average in-ground pool owner. It pairs a digital control panel that actually helps with self-diagnostics, a 250,000 BTU output that handles most residential pools up to 25,000 gallons, and a low-NOx certification that clears emissions rules in restrictive regions. For a salt water pool, the upgrade to a cupro-nickel unit is worth the price jump, and the Raypak 406K Digital Natural Gas is the strongest premium choice thanks to its 4.4 star average and the longest expected service life in this roundup.

If you are on propane and want the largest BTU output, the Raypak 406K propane is the Top Rated option, with the lowest one-star review share of any 400K propane unit we covered. For a small in-ground pool under 15,000 gallons, the Pentair EC-462024 on natural gas or the EC462025 on propane will save you real money upfront while still delivering 82% thermal efficiency. Match the BTU class to your pool volume, choose cupro-nickel for any salt water pool, and have your installer verify the gas line size before you order. With those three decisions made, you will end up with the best gas pool heater for an in-ground pool in 2026 that fits your pool, your fuel, and your climate.