A pool heater is the difference between a four-month swim season and a nine-month one, but the three technologies available differ enormously in how they spend your money. Gas heaters are cheap to buy and expensive to run. Heat pumps are the reverse. Solar is nearly free to operate and useless on the days you most want heat. This guide gives real 2026 installed pricing and monthly operating costs for each, explains how to size correctly, and helps you match the technology to how you actually use the pool.
A natural gas or propane pool heater runs $2,800 to $6,500 installed for a typical 250,000 to 400,000 BTU residential unit. The equipment is $1,800 to $4,200 and the rest is labor, plumbing tie-in, and gas line work. If your existing gas line cannot supply the volume — and for a 400,000 BTU heater it frequently cannot — running an upsized line adds $500 to $2,500 depending on distance and whether it is trenched.
Electric heat pump pool heaters cost $3,500 to $8,000 installed, with the equipment at $2,500 to $5,500 and a dedicated 240-volt 50-amp circuit adding $400 to $1,200 if one does not exist. Solar pool heating systems run $3,500 to $9,000 installed for enough roof-mounted collector area to cover a typical pool, and small electric resistance heaters, which are only practical for spas, are $1,500 to $3,000.
This is where the choice is decided. Heating a 20,000 gallon pool with natural gas at $1.60 per therm costs roughly $250 to $500 per month for a pool kept at 84 degrees during the shoulder season. On propane at typical 2026 pricing that same pool is $500 to $1,000 a month, which is why propane pool heating only makes sense for occasional weekend use.
A heat pump on the same pool costs $120 to $300 a month at 15 cents per kWh — roughly half to a third of gas — because it moves ambient heat rather than creating it. Solar costs essentially nothing beyond the pump energy you were already spending. The trade-off is speed and reliability: gas raises water temperature 1 to 1.5 degrees per hour regardless of weather, a heat pump manages 0.25 to 0.5 degrees per hour and only when the air is above roughly 50 degrees, and solar only works when the sun is out.
Choose gas if you use the pool intermittently and want it hot on demand — a weekend house, a pool used mostly for guests, or any spa. Gas heaters recover fast from cold and do not care about air temperature, which makes them the only real option for extending the season into genuinely cold weather. The cost of that flexibility is a fuel bill you feel every time you use it.
Choose a heat pump if you swim regularly and want to hold a temperature all season, particularly in a climate where daytime highs stay above about 55 degrees during your swim months. Choose solar if you have unshaded south-facing roof area roughly equal to 50 to 100 percent of your pool's surface area and your goal is extending the natural season by four to eight weeks rather than defeating winter. Many owners in mild climates pair solar with a small gas heater as backup, which is the lowest lifetime-cost combination.
Undersizing is the most common mistake. For gas, a workable rule is 1 BTU per gallon as a minimum, so a 20,000 gallon pool wants at least a 250,000 BTU heater, and going up a size costs only a few hundred dollars while cutting heat-up time substantially. For heat pumps, size by surface area and desired temperature rise — a 400 square foot pool typically needs 110,000 to 140,000 BTU of heat pump capacity in a warm climate and more in a cool one.
Then buy a cover. Evaporation accounts for roughly 70 percent of a heated pool's heat loss, and a $150 to $400 solar cover cuts heating costs 40 to 70 percent on any system. It is the single highest-return purchase in pool ownership, and it also reduces chemical consumption and water top-off. A $400 automatic reel makes it likely you will actually use the cover, which is the part most owners get wrong.
Gas heaters last 5 to 10 years, and shorter than that if pool chemistry runs acidic — low pH eats the copper heat exchanger, which is the most expensive component. Heat pumps last 10 to 20 years because there is no combustion and no corroding exchanger under flame. Solar collector panels last 10 to 20 years and typically fail through UV embrittlement of the headers rather than the tubes.
Common repairs: a gas heater ignition control or igniter is $200 to $500, a pressure switch is $120 to $300, and a copper heat exchanger is $700 to $1,800 which on an older unit means replacing the heater. Heat pump repairs run $250 to $900 for capacitors, fan motors, or control boards, with compressor failure at $1,200 to $2,500. Keep pH between 7.4 and 7.6 and calcium hardness in range and you will roughly double the heat exchanger's life.
Gas heaters run $2,800 to $6,500 installed, electric heat pumps $3,500 to $8,000, and solar systems $3,500 to $9,000. Add $500 to $2,500 if a gas heater needs an upsized supply line, or $400 to $1,200 for a dedicated 240-volt circuit for a heat pump. Those infrastructure items are the most common source of quote-to-quote variation.
Solar, by a wide margin — it adds essentially nothing beyond pump energy you already use. Among heaters you can run on demand, a heat pump costs roughly $120 to $300 a month versus $250 to $500 for natural gas and $500 to $1,000 for propane on a 20,000 gallon pool held at 84 degrees. A solar cover cuts any of those figures by 40 to 70 percent.
A properly sized gas heater raises water temperature 1 to 1.5 degrees per hour, so warming a 20,000 gallon pool from 70 to 84 degrees takes about 10 to 14 hours. A heat pump manages 0.25 to 0.5 degrees per hour, requiring 24 to 72 hours for the same rise. Solar depends entirely on sun and typically adds 5 to 10 degrees over several sunny days.
Only down to a point. Most pool heat pumps lose significant capacity below 50 degrees ambient and shut off entirely around 45 degrees, since they extract heat from outdoor air. That makes them excellent for holding temperature through a long mild season and unsuitable for true winter swimming. In cold climates, gas or a gas-backed hybrid is the workable choice.
It is the highest-return item in pool ownership. Evaporation causes about 70 percent of heat loss from a heated pool, and a $150 to $400 cover cuts heating costs 40 to 70 percent while reducing chemical use and water top-off. Add a $300 to $700 reel — owners who have to wrestle the cover by hand stop using it within a month.
Gas heaters last 5 to 10 years, heat pumps 10 to 20, and solar collectors 10 to 20. The main killer of gas heaters is acidic water corroding the copper heat exchanger, a $700 to $1,800 part that usually ends the unit's economic life. Holding pH between 7.4 and 7.6 with calcium hardness in range roughly doubles heat exchanger lifespan.