What is the best type of pool heater for a Florida pool?

For most Florida residential pools, a heat pump is the default answer. Our mild winters keep the air above roughly 55 degrees most days, so a heat pump gives you the lowest running cost in the state, even though it heats slower. Go gas only when you need a cold pool hot fast a few times a year, like a weekend home or rental. Solar is a great supplement to stretch the season, rarely a standalone heater.

How do I size a pool heater so I don't buy one too small?

Run the math builders use: BTU equals gallons times 8.33 pounds per gallon times the desired degree rise. That is the one-time energy to bring the pool up to temperature. For a 20,000-gallon pool rising 10 degrees, that is 1,666,000 BTU total. Divide that by the heater's output and by the hours you are willing to wait to get heat-up time. Add 4 percent for every 1,000 feet above sea level, which barely matters anywhere in Florida. Under-sizing is the most common mistake on Florida builds.

What does COP mean on a pool heat pump and why should I care?

COP is Coefficient of Performance, the ratio of heat output to the electricity the unit burns. An electric resistance heater has a COP of 1, so one unit of electricity gives you one unit of heat. A modern pool heat pump is AHRI-rated at COP 5 to 6 at 80-degree air and water, with some inverter units pushing near 6.5 in ideal conditions. That means 5 to 6 times the heat for the same power bill. Cold air drops COP, and a scroll-compressor unit holds performance better in cold ambient than an older reciprocating design.

Is a solar heater enough to heat a Florida pool on its own?

Rarely. Solar pumps pool water through black panels in direct sun and gains 5 to 10 degrees on a good day, and it is essentially free to run after install with no fuel and only minor pump energy. The catch is it is weather-dependent, so it is a great supplement, not a standalone answer. The move that works is pairing solar with a heat pump: solar extends the season for pennies and you only fire the heat pump on cloudy days.

Why is a heat pump the right call for most Florida pools?

Our mild winters do the heavy lifting. On most days the ambient air stays above roughly 55 degrees, which is the temperature floor below which a heat pump's efficiency tanks. Stay above it and you get the lowest running cost of any heater type in the state, typically 3 to 8 times more efficient than electric resistance. You trade a slower heat-up for that low operating cost, which is the right trade for a pool you keep warm through the season rather than firing hot on short notice.

How many months of the year does a Florida pool actually need a heater?

A Florida pool is warm for most of the year without any help. The real question is what to do about the 4 to 6 months when it isn't, and how you want to pay for that decision over the next decade. That short cold window is exactly why a heat pump fits most homeowners: you keep the pool comfortable through the cool months at the lowest running cost, and only lean toward gas if you need a cold pool hot fast a handful of times instead of holding temperature all season.

Pool Equipment Guide: Pumps, Filters, Heaters & Salt · 7 min read · By Matt Balog

Pool Heaters: Gas, Heat Pump, and Solar Compared

Florida-specific heater guidance: when a heat pump wins, when gas is worth it, and when solar is enough.

By Matt Balog, Founder & Lead Pool Technician · Updated July 4, 2026 · 7 min read

Quick answer

A heat pump is the default answer for most Florida residential pools — mild winters keep the air above ~55°F, so you get the lowest running cost in the state.
Gas heats fast but costs the most per hour — a 400k BTU unit raises a 15,000-gallon pool about 1°F an hour, best for weekend homes and rentals that need it hot on short notice.
Solar is a supplement, rarely a standalone — it gains 5–10°F on a good day for essentially free, so pair it with a heat pump and only run the pump on cloudy days.
Under-sizing is the single most common mistake — BTU equals gallons times 8.33 times the desired °F rise, then divide by output to get heat-up time.
A modern heat pump is AHRI-rated at COP 5–6, meaning 5 to 6 times the heat per electric dollar versus a resistance heater's COP of 1.
Electric resistance heaters are a Florida anti-pattern — slow, expensive, and outclassed by heat pumps in every way that matters.

A Florida pool is warm for most of the year without any help. The question is what to do about the 4–6 months when it isn't, and how to pay for that decision over the next decade. There are three mainstream heater types on the market, each with a clear use case. Pick wrong and you'll either be cold six months a year or watch the gas meter spin harder than the pool pump.

The three heater types, in plain English

Type	How it heats	Speed	Operating cost
Gas (natural or propane)	Burns fuel under a heat exchanger.	Fast — raises a 15,000-gal pool ~1°F per hour at 400k BTU.	High per hour. Best for short, intense use.
Heat pump (electric)	Moves heat from the outside air into the water, like an AC run in reverse.	Slow — needs 24–72 hours to bring a cold pool up 10°F.	Low per hour. Typically 3–8x more efficient than electric resistance.
Solar	Pumps pool water through black panels in direct sun.	Weather-dependent. Gains 5–10°F on a good day.	Essentially free after install. No fuel, minor pump energy.

How to pick, Florida edition

Heat pump is the default answerfor most Florida residential pools. Our mild winters keep ambient air above ~55°F on most days — the temperature floor below which a heat pump's efficiency tanks. You trade a slower heat-up for the lowest running cost in the state.
Gas makes sense when you use the pool rarely but want it hot fast— weekend homes, vacation rentals, or when a cold snap hits a heat pump harder than the owner wants to wait out.
Solar is a great supplement, rarely a standalone answer. Pair solar with a heat pump to extend the season for pennies and only run the heat pump on cloudy days.
Electric resistance heaters (other than small spa-only units) are a Florida anti-pattern. Slow, expensive, and outclassed by heat pumps in every way that matters.

Sizing — the math that protects your budget

Under-sizing a heater is the single most common mistake on Florida pool builds. The rule of thumb pool builders use:

BTU = Gallons × 8.33 lb/gal × desired °F rise— the one-time energy to raise the pool to temperature.
Divide BTU by the heater's output and by the hours you're willing to wait to get heat-up time.
Add 4% for every 1,000 ft above sea level. Irrelevant in most of Florida; matters in Orlando's higher elevations barely.

For a 20,000-gallon pool rising 10°F: 20,000 × 8.33 × 10 = 1,666,000 BTU of total energy needed. A 400,000 BTU/hr gas heater delivers that in about 4 hours. A 140k BTU/hr heat pump does it in about 12 hours.

The COP conversation (for heat pumps)

Coefficient of Performance (COP) is the ratio of heat output to electrical energy consumed. An electric resistance heater has a COP of 1 — one unit of electricity delivers one unit of heat. A modern pool heat pump is AHRI-rated at COP 5–6 (80°F air, 80°F water; some inverter units approach 6.5 at ideal conditions), which means for the same electricity bill you get 5–6 times the heat. Colder air lowers COP; scroll-compressor units keep performance higher at cold ambient than older reciprocating designs.

Bottom line for most Florida homeowners: size a heat pump for your pool, consider adding solar if your roof works, and only go gas if you genuinely need to heat a cold pool on short notice a few times a year.

Pool heater sizing calculator

Surface area × temperature rise × 12 = required heater output. Surface area drives it — evaporation is where pools lose heat.

Surface area (sq ft)

Target water temp (°F)

84–88°F is the family sweet spot.

Coldest-month water temp (°F)

South Florida unheated pools bottom out in the low-to-mid 60s.

Gas heater: 200k BTU nameplate

A 19°F rise on 392 sq ft needs ≈ 89,000 BTU/hr of output (≈ 109k input at ~82% efficiency). Oversizing a gas heater is fine — it just reaches temperature faster. Undersizing means it runs forever on cold weekends. Heat pumps are rated differently (typically 110k–140k BTU output) and heat slower but far cheaper per degree — the right call for set-and-hold temperature in South Florida; gas wins for fast weekend heat-ups.

Reference sizing for an uncovered residential pool with typical wind exposure, per manufacturer surface-area charts. A solar cover cuts the real load dramatically. Final sizing and gas-line capacity are the installer's responsibility.

Frequently asked questions

Gas is the fast option. A 400,000 BTU gas heater raises a 15,000-gallon pool about 1 degree an hour, and for a 20,000-gallon pool needing a 10-degree rise it delivers the full heat-up in about 4 hours. A heat pump is slow by comparison, needing 24 to 72 hours to bring a cold pool up 10 degrees; a 140k BTU heat pump does that same 20,000-gallon rise in about 12 hours. Gas wins on speed, heat pump wins on running cost.