You’ve decided to heat your pool. Good. The hard part is over. Now comes the question I get on almost every quote call: “Do I get a regular heater or a heat pump?”
Here’s the honest answer most people don’t expect. In Hawaii, the wrong choice can cost you an extra $2,000 a year. The right one can pay for itself in comfort and HECO savings within a few seasons. Same goal, very different math.
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 every type of heater in every kind of home from Portlock to Hawaii Loa Ridge. So let me settle the gas-heater-versus-heat-pump question the way I’d explain it to you standing next to 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 in front of you is gas versus electric heat pump. Those are the two contenders.
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
You can’t pick the right tool until you know what each one does. The difference is everything.
Gas Heater (Propane)
Burns propane in a combustion chamber and pushes that heat into your water through a heat exchanger. Think of it like a giant gas stove for your pool. It makes 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)
Doesn't make heat. It moves it. A heat pump grabs warmth out of the surrounding air and transfers it into your water, basically an air conditioner running backwards. Because it's moving heat instead of burning fuel, it uses roughly one-fifth the energy of a gas heater per degree. The catch: it works slower, 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. Here’s the thing: 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 hobbles heat pumps everywhere else doesn’t exist where you live. Hold onto that. It decides this whole comparison.
Round 1: Heating Speed
Gas wins this round, and it isn’t close.
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 is the tortoise: it adds heat gradually, often taking 24 to 48 hours to bring a cool pool up to temperature from scratch.
But read that carefully, because it’s a trap most homeowners fall into.
You only feel that speed difference on the initial heat-up. Once your pool is at temperature, a heat pump holds it there easily and cheaply. The question isn’t “which heats faster from cold.” It’s “how do you actually use your pool?” If you swim regularly, you’re maintaining a temperature, not racing to heat from cold every time. And maintaining is exactly what a heat pump does best.
The honest version: Gas wins on speed only if you let your pool go cold between uses. If you keep it warm and just swim, a heat pump's slower heating never even shows up in your day.
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 it’s the wrong number to fixate on, and the next round shows you why. The sticker price is a one-time event. The running cost shows up on every single HECO bill for the next decade.
Round 3: Running Cost (This Is the One That Matters)
Here’s where Hawaii flips the whole script.
We pay the highest electricity rates in the country, roughly 42¢ per kilowatt-hour, more than double the mainland average. That’s the same brutal 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.
So both fuels are expensive in Hawaii. The difference is how much of each you burn. And a heat pump sips while a gas heater guzzles.
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 is just handing money back to you. Look at the full picture over five years and it isn’t close.
Want your actual numbers, not a range?
Tell me your pool size and how you use it, and I'll calculate what each option would really cost you on your HECO bill. No guessing.
Call 808-399-4388Round 4: Lifespan and Salt Air
Living near the ocean changes everything about pool equipment, and heaters are no exception. 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?
I’m not going to pretend one answer fits everyone. It doesn’t. Here’s how I size it up on a quote call, depending on the home.
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 wins so decisively it isn't worth debating. 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 the same thing: the cover is the second purchase, not optional.
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 every month, lasts longer, and our climate is practically built for 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, choose the heat pump and don't look back.
The mistake I hate watching people make is buying a gas heater because the sticker price was lower, then opening their first propane-season HECO statement and realizing they’ll pay that gap back ten times over. The cheap heater is rarely the cheap choice. 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. No upsell, no pressure. 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 doesn't create heat, it moves existing heat from the air into your water, 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 one weakness that holds heat pumps back elsewhere simply doesn't apply 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 evaluate your current setup during a free on-site visit.
