So you’ve decided to heat your pool. The next question comes up on almost every quote call I take: “Do I get a regular heater or a heat pump?”
Most people don’t expect how much rides on that answer. In Hawaii, the wrong choice can cost you an extra $2,000 a year. The right one can pay for itself in comfort and lower bills within a few seasons.
I’m Paul Costello. My father Jim started Koko Head Pool Service in 1995, and I’ve been servicing pools across East Honolulu since 2000. Between us, we’ve installed and repaired just about every type of heater in homes from Portlock to Hawaii Loa Ridge. Here’s how I’d explain the choice if we were standing at your equipment pad.
First, Let’s Clear Up the Confusion
A heat pump is a pool heater. Technically, they’re all heaters. But when a homeowner says “heater,” they almost always mean a gas heater: the unit that burns propane to heat your water. And when they say “heat pump,” they mean the electric unit that pulls warmth out of the air.
So the real decision is gas versus an electric heat pump.
There’s a third option, solar, and in Hawaii it’s a serious one. But solar is its own conversation, and I cover the full three-way breakdown in my guide on whether a pool heater is worth it in Hawaii. This post is the head-to-head most people are actually stuck on: gas heater or heat pump.
How Each One Actually Works
Start with what each one does, because the way they work drives everything else.
Gas Heater (Propane)
Burns propane in a combustion chamber and pushes that heat into your water through a heat exchanger. It works like a big gas burner for your pool, making heat on demand, fast, no matter how cold the air is. In most East Honolulu neighborhoods there's no natural gas line, so you're running a propane tank that needs refills.
Heat Pump (Electric)
A heat pump moves heat instead of making it. It pulls warmth out of the surrounding air and transfers it into your water, basically an air conditioner running backwards. Because it isn't burning fuel, it uses roughly one-fifth the energy of a gas heater per degree. It's slower, though, and it needs warm air to pull from.
That last line about heat pumps needing warm air? On the mainland it’s a real weakness. Heat pump efficiency starts dropping once air falls below about 50°F. East Honolulu almost never gets that cold. Our air rarely dips below 60°F, even on a winter morning in Hawaii Loa Ridge. The one thing that holds heat pumps back everywhere else barely exists here, and that ends up deciding this comparison.
Round 1: Heating Speed
Gas wins this round easily.
A gas heater can raise a typical residential pool 1 to 2 degrees per hour. Fire it up in the morning, and your pool is warm by afternoon. A heat pump adds heat gradually and often takes 24 to 48 hours to bring a cool pool up to temperature from scratch.
A lot of homeowners stop reading there, and that’s a mistake.
You only feel the speed difference on the first heat-up. Once the pool is at temperature, a heat pump holds it there easily and cheaply. So think about how you use your pool. If you swim regularly, you’re holding a temperature, not heating from cold every time, and holding temperature is what a heat pump does best.
In practice: Gas only wins on speed if you let the pool go cold between uses. If you keep it warm and just swim, you'll never notice that a heat pump heats slower.
Round 2: Upfront Cost
Gas takes this round, but by less than you’d think.
Gas Heater
Heat Pump
A heat pump runs maybe $1,000 to $1,500 more out the door. That gap feels real when you’re writing the check. But you pay the sticker price once. The running cost shows up on every bill for the next decade, which is the next round.
Round 3: Running Cost (This Is the One That Matters)
This is where Hawaii changes the answer.
We pay the highest electricity rates in the country, roughly 42¢ per kilowatt-hour, more than double the mainland average. It’s the same math I broke down in my variable speed pump guide. Propane isn’t cheap here either, running $4 to $6 a gallon once it’s shipped across the Pacific.
Both fuels are expensive here. What matters is how much of each you burn, and a heat pump burns far less.
Now run that gap forward.
That higher upfront cost on the heat pump? For a regular swimmer, it disappears inside the first year of fuel savings. After that, the heat pump keeps saving you money every month. Over five years, the gap is wide.
Want your actual numbers, not a range?
Tell me your pool size and how you use it, and I'll work out what each option would cost you to run.
Call 808-399-4388Round 4: Lifespan and Salt Air
Living near the ocean is hard on all pool equipment, heaters included. Salt air corrodes metal, and the part it attacks is different in each unit.
Gas Heater Lifespan
Heat Pump Lifespan
The heat pump wins this round too. It lasts longer and costs less to maintain. Either way, salt air is the enemy, and I explain exactly how it eats equipment in my post on Hawaii’s salt air and volcanic water damage. A freshwater rinse and an annual inspection through our equipment service buys you years on either unit. When a heater does fail, our pool heater repair service handles both gas and heat pump units on-site.
Which One Is Right for You?
One answer doesn’t fit everyone. This is how I size it up on a quote call.
This is most of my clients in Hawaii Kai, Kahala, and Aina Haina. If the pool is part of your routine, the low running cost settles it. Our warm air makes heat pumps perform better here than almost anywhere in the country. It's the unit I install most.
Weekend gatherings, the holidays, a pool you let go cool most of the time and want hot fast for a party. Gas heats in hours, not days, and the high fuel cost matters less when you're barely running it. This is also the right call for many vacation rentals where guests want heat on demand.
If your home has photovoltaic panels making electricity, a heat pump becomes almost free to run. You're heating your pool with your own solar power, just indirectly. A gas heater can't tap into that at all.
A $50 to $150 solar cover cuts heating costs by 50 to 70% by stopping evaporation, and in our trade winds evaporation is where most of your heat escapes. I tell every heater client to buy the cover right after the heater.
My Honest Recommendation
For most East Honolulu homeowners, the heat pump is the right call. It costs a little more upfront, then saves you $100 to $280 a month, lasts longer, and our climate suits it. The only strong case for gas is occasional, on-demand heating where speed beats efficiency. If you're going to swim in this pool regularly, get the heat pump.
The mistake I hate watching is someone buying a gas heater because the sticker price was lower, then getting their first few propane bills and realizing they’ll pay that difference back many times over. For more ways to keep your pool affordable, see my guide on saving money on your pool, and for the full cost of pool ownership here, my Hawaii pool service cost guide.
Not sure which one fits your pool?
I'll look at your setup, how you actually use your pool, and your budget, then give you a straight recommendation without pushing you toward the pricier unit. That's how we've done it since 1995.
Get a Free QuoteKoko Head Pool Service installs and repairs pool heaters and heat pumps throughout East Honolulu:
Hawaii Kai · Portlock · Kahala · Diamond Head · Aina Haina · Hawaii Loa Ridge · Waialae Iki · Kalama Valley · Kuliouou · Hahaione
Call 808-399-4388 or get a free quote.
Frequently Asked Questions
Is a heat pump better than a gas heater in Hawaii?
For most East Honolulu homeowners, yes. A heat pump costs more upfront ($3,000 to $6,500 vs. $2,000 to $5,000 for gas) but runs on roughly one-fifth the energy, costing $40 to $120 a month compared to $150 to $400 for a gas heater. It also lasts longer and our warm air makes it especially efficient here. The main exception is occasional, on-demand heating, where a gas heater's faster warm-up is the better fit.
Why is a heat pump cheaper to run than a gas heater?
A gas heater creates heat by burning propane, which takes a lot of fuel. A heat pump moves existing heat from the air into your water instead of creating it, so it uses far less energy for the same result, about one-fifth as much per degree. With Hawaii's high electricity and propane prices, that efficiency gap turns into hundreds of dollars in savings every month for a regularly used pool.
How long does it take a heat pump to heat a pool in Hawaii?
From cold, a heat pump typically takes 24 to 48 hours to bring a 15,000-gallon pool up to temperature. A gas heater does it in 8 to 12 hours. But that speed only matters on the initial heat-up. Once your pool is warm, a heat pump holds the temperature easily and cheaply, which is why it's the better choice if you swim regularly rather than heating from cold each time. A solar cover speeds up both options significantly.
Do heat pumps work well in Hawaii's climate?
Better than almost anywhere in the country. Heat pumps lose efficiency when air temperatures drop below about 50°F, which is a real problem on the mainland in winter. East Honolulu's air rarely falls below 60°F, even on cool winter mornings, so a heat pump stays in its efficient operating range year-round. The weakness that holds heat pumps back elsewhere barely applies here.
Should I get gas or a heat pump for a vacation rental pool?
For a vacation rental, a gas heater often makes more sense. Guests typically want the pool hot quickly for their stay, and a gas heater can deliver a fast warm-up on demand. Since the pool isn't running a heater every day, the higher fuel cost matters less. For an owner-occupied home where the family swims regularly, the heat pump's low running cost usually wins.
Can I switch from a gas heater to a heat pump?
Yes. A heat pump plumbs into the same return line after your filter, so swapping from gas to a heat pump is straightforward in most setups. The main considerations are space on your equipment pad and adequate electrical capacity, usually 220V. If your gas heater is aging or failing, switching to a heat pump at replacement time is often the smartest long-term move. We can look at your current setup when we come out to quote it.
