10 Best Inground Pool Heaters 2025 in the United States

The Hayward W3H400FDN is a strong choice for heating inground pools and spas, offering a powerful 400,000 BTU heating capacity that suits larger pool sizes or those in cooler climates. Its cupro-nickel heat exchanger stands out by resisting corrosion, which is a big plus if your pool water chemistry isn't always perfectly balanced. This means fewer worries about repairs from rust or buildup over time.

The heater also boasts an efficient hydraulic design that helps reduce the pump’s running time, potentially lowering your energy bills. For those concerned about environmental impact, it produces low NOx emissions, meeting strict air quality standards. Operation and maintenance are user-friendly thanks to the front-panel access and simple control pad, making it easier to manage without professional help.

This model is quite heavy and sizable, so installation might require effort and space considerations. While it excels in heating power, it may entail higher upfront and operating costs compared to smaller or less efficient models. If you have a large inground pool and want dependable, fast heating with energy-saving features, this heater is a fitting option. For smaller pools or budget-conscious users, a lower-capacity or more affordable heater might be more suitable.

The Hayward W3H250FDN is a powerful natural gas pool heater designed for inground pools and spas, offering a strong heating capacity of 250,000 BTUs. This makes it suitable for larger pools or those in cooler climates where faster or more consistent heating is important. Its cupro nickel heat exchanger is especially durable, providing good resistance to corrosion—a common issue that shortens many pool heaters’ lifespans. Energy efficiency is boosted by smart hydraulic design that reduces pump run time, helping save on energy bills over time. The heater also features low NOx emissions, which is better for the environment and meets strict air quality standards in many areas.

Installation and maintenance are user-friendly thanks to easy front-panel access and a straightforward control pad, meaning you won’t need specialized skills for basic upkeep. On the downside, the unit is fairly heavy and large, so professional installation might be necessary, adding to initial costs. Gas heaters, including this model, can lead to higher operating costs compared to electric or solar options. This heater is an excellent choice if you want a reliable, strong, and environmentally considerate gas heater for an inground pool, especially if you prioritize durability and easy maintenance.

The Raypak 266,000 BTU Digital Electronic Ignition Natural Gas Pool Heater is a powerful option for heating inground pools or spas, with its high heating capacity making it suitable for larger pools or cooler climates that require strong heating performance. Its natural gas operation and radiant burner type provide efficient heat output, which is enhanced by the intermittent spark ignition system that only activates the pilot when heating is needed, helping to save energy and reduce fuel costs.

The heater uses a special space-age material that quickly cools down after use, eliminating the need for extra metal heat sinks, which can simplify installation and reduce expenses. Designed to be durable against various weather conditions, it works well outdoors and has a programmable thermostat for user convenience and better temperature control. However, weighing in at 210 pounds and requiring floor mounting, it may need professional help for installation.

Energy efficiency is improved compared to some older models, although natural gas operation might not be the most cost-effective option everywhere depending on local gas prices. This Raypak model is an excellent choice for those needing a strong, weather-resistant pool heater with good energy-saving features, especially in climates with cooler seasons or for larger pool sizes.