Heat Pump vs. Natural Gas Pool Heaters

If you want to extend your swimming season beyond the five or six months when your Phoenix pool is naturally comfortable, you need a heater. The two most common options are heat pumps and natural gas heaters — and they work in fundamentally different ways. Understanding the differences helps you choose the right system for how you actually use your pool.

How They Work

Natural Gas Heaters

A gas heater burns natural gas (or propane) in a combustion chamber. Pool water flows through a heat exchanger where the combustion heat transfers directly to the water. The process is simple, fast, and effective regardless of outside air temperature.

Heat Pumps

A heat pump doesn’t generate heat — it transfers it. Using the same refrigerant cycle as an air conditioner (but in reverse), it extracts heat from the outside air and transfers it to the pool water. Electricity powers the compressor and fan, but the actual heating energy comes from ambient air temperature.

This is why heat pumps are often described as having a COP (Coefficient of Performance) of 5.0 or higher — for every unit of electricity consumed, the system moves 5 units of heat energy into the pool.

Efficiency and Operating Cost

This is where the comparison gets interesting, especially in Arizona.

Natural gas heaters have thermal efficiency ratings around 80–95% (for modern units). They consume gas at a rate proportional to the temperature rise you need. Heating a pool from 60°F to 82°F uses more gas than maintaining it at 82°F. Monthly operating costs during heating season can range from $200–$500+ depending on pool size, desired temperature, and gas rates.

Heat pumps are dramatically more efficient in terms of energy-to-heat conversion. In Phoenix, where winter air temperatures rarely drop below 40°F (and daytime temps are often 50–70°F through winter), heat pumps operate in their ideal range for most of the year. Monthly electricity costs for heat pump operation typically run $50–$150.

Over a 10-year period, the cumulative operating cost difference is substantial — often enough to offset the higher upfront cost of a heat pump.

Heating Speed

Natural gas wins here — decisively. A gas heater can raise pool temperature 1–2°F per hour in a typical residential pool. If you want the pool heated for a weekend gathering and it’s currently 60°F, a gas heater can get you there in a day.

Heat pumps are slow. Temperature rise of 1–3°F per day is typical, depending on conditions. A heat pump is designed to maintain a set temperature over time, not to rapidly heat a cold pool. If you decide on Wednesday that you want a warm pool by Saturday, a heat pump may not get there — especially if nighttime temperatures are dropping the water back down.

Lifespan

Natural gas heaters: 5–10 years typical lifespan. Copper heat exchangers corrode over time, particularly if water chemistry is not well maintained. Low pH and high calcium accelerate failure.
Heat pumps: 10–15+ years typical lifespan. The titanium heat exchangers in quality heat pumps are highly resistant to chemical corrosion. Fewer combustion components means fewer failure points overall.

Heat pumps generally require less maintenance — no gas valve issues, no igniter replacements, no heat exchanger corrosion from combustion byproducts.

Installation Considerations

Gas heaters require:

A natural gas line run to the equipment pad (if not already present)
Adequate gas supply (BTU capacity shared with other appliances)
Proper venting clearances
Gas line permits and inspection

Heat pumps require:

A dedicated electrical circuit (typically 30–60 amps, 240V)
Adequate airflow space around the unit (they pull air through the evaporator coil)
More physical space on the equipment pad than a gas heater

Both require professional installation by a licensed contractor. Neither is a DIY project.

Arizona Climate Advantage for Heat Pumps

Phoenix’s climate is almost ideal for heat pump pool heating:

Mild winters — daytime temps of 60–75°F through December–February give the heat pump abundant ambient heat to work with
Low humidity — heat pumps perform well in dry air
Extended shoulder seasons — October and April are months where a heat pump easily maintains comfortable water temps with minimal energy
Sunshine — solar gain on the pool surface supplements the heat pump’s work during the day

In climates with harsh winters (temperatures consistently below 40°F), heat pumps struggle and gas becomes the only practical option. Phoenix rarely presents that scenario.

Which Should You Choose?

Choose a gas heater if:

You heat your pool infrequently and want rapid heat-up
You entertain and need the pool warm on short notice
You already have a gas line at the equipment pad
Upfront cost is the primary concern

Choose a heat pump if:

You want to maintain a consistent temperature throughout the season
You swim regularly from October through April
You want the lowest possible operating cost over time
Equipment longevity matters to you

Consider both (dual system) if:

You want the best of both worlds — daily efficiency from the heat pump with the option to boost quickly with gas when needed
Budget allows for dual installation

Need help choosing or installing a pool heater in Phoenix? Contact Splash Mob Pools for an equipment consultation tailored to your pool and usage pattern.