Quick answer: choose a heat pump if you swim mostly in warm months, the air is usually above 50°F, and you want the lowest monthly running cost. Choose a gas heater if you want fast heat on demand, heat a spa, swim in cool weather, or only heat the pool now and then.
Both are good choices. They just solve different problems. Here is how they compare on cost, speed, climate and installation.
How each one heats
A gas heater burns natural gas or propane and passes pool water through a heat exchanger. It makes heat directly, so it works the same whether it is 40°F or 90°F outside.
A heat pump does not make heat. It pulls heat out of the outside air with a fan and refrigerant, the same way an air conditioner works in reverse, and moves that heat into the water. Because it moves heat instead of making it, it delivers 3 to 7 units of heat for every unit of electricity it uses, according to the U.S. Department of Energy.
Heat pump vs gas heater at a glance
| Heat pump | Gas heater | |
|---|---|---|
| Efficiency | 300 to 700 percent (COP 3 to 7) | About 80 to 95 percent |
| Heat-up speed | Slow, often about 1°F per hour or less | Fast, often several degrees per hour |
| Best air temperature | Above 50°F | Any weather |
| Up front price | Usually higher | Usually lower |
| Running cost | Usually lower | Usually higher |
| Spa heating | Slow | Excellent |
| Lifespan | Often 10+ years with care | Often shorter than a heat pump |
| Hookup | Dedicated electrical circuit, open airflow | Gas line sized for the BTU, venting clearances |
Running cost
Heat pumps win here in most warm climates. The Department of Energy estimates that a heat pump with a COP of 5 costs about 30 percent less to run each year than an older gas heater at 55 percent efficiency. Against a modern gas heater at about 75 percent efficiency, the savings shrink to a few percent, so local gas and electric prices matter a lot.
The DOE also shows how much a cover changes the math. For a 1,000 sq ft pool heated March through October in Phoenix, a heat pump cost about $1,192 a year without a cover and about $116 with one. Whatever heater you choose, use a cover.
Speed
Gas is the clear winner. If you want to turn the heat on Friday for a Saturday party, or heat a spa in 20 to 30 minutes, you want gas. Heat pumps are best left running to hold the pool at a steady temperature through the season.
Climate
Heat pumps lose efficiency as the air gets colder and work best above 50°F. In mild areas such as much of Southern California, a heat pump can cover most of the swim season. In places with cold springs and falls, or for winter spa use, gas is the more dependable choice.
If you live in California, check whether your local air district requires a Low NOx gas heater. Many current models, including the Hayward H-Series 400K Low NOx, are built for those rules.
Installation
- Heat pump: needs a dedicated 230V circuit and plenty of open space around the unit so it can pull in air. No gas line or flue.
- Gas heater: needs a gas line large enough for the heater's BTU rating and proper clearance for venting. Larger heaters often need a bigger gas meter or line.
Which one should you buy?
Pick a heat pump if:
- You swim from late spring to early fall
- Your air is usually above 50°F when you swim
- You want low monthly bills and keep the pool warm all season
- You do not have a gas line near the equipment pad
Pick a gas heater if:
- You have a spa or want heat in a hurry
- You swim early spring, late fall or winter
- You only heat for weekends or special days
- You already have a gas line at the pad
Some owners use both. A heat pump holds the pool warm all season at low cost, and a gas heater handles the spa and cold snaps.
Popular choices
- Raypak Crosswind V 8550 heat pump, 138K BTU with a titanium heat exchanger and Wi-Fi
- Raypak Crosswind V 6550 heat pump, 112K BTU for mid size pools
- Raypak 266K digital natural gas heater, our best selling gas heater
- Raypak 406K digital natural gas heater for large pools and fast spa heat
See all options in pool heat pumps, Raypak heat pumps, pool heaters and Hayward heaters. Raypak heaters and heat pumps ship free.
Not sure what size you need? Use our pool heater sizing guide.
Heat pump vs gas heater FAQ
Is a heat pump cheaper to run than a gas heater?
In most warm climates, yes. A heat pump turns one unit of electricity into 3 to 7 units of heat, while a gas heater turns most, but not all, of its fuel into heat. Your actual savings depend on your local gas and electric rates.
Can a heat pump heat a spa?
It can, but slowly. Most spa owners who want hot water in under an hour use a gas heater for the spa.
Do pool heat pumps work in winter?
They keep working in cool weather but lose efficiency as the air drops below about 50°F. For regular winter swimming, gas is more reliable.
How long does a pool heat pump last?
With yearly service, heat pumps often last 10 years or more, which is typically longer than a gas heater.
Can I switch from gas to a heat pump?
Yes. You will need an electrician to run a dedicated circuit, and the heat pump needs open space around it for airflow. The plumbing hookup is similar to a gas heater.