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 Hayward W3H150FDN Universal H-Series 150,000 BTU Natural Gas Pool and Spa Heater is designed for in-ground pools and spas, providing reliable and efficient heating. One of its significant strengths is the robust 150,000 BTU heating capacity, making it suitable for small to medium-sized pools and spas. The heater features a durable cupro nickel heat exchanger, offering strong protection against corrosion, which is particularly beneficial if your pool has unbalanced water chemistry. This contributes to its longevity and reliability.

Another advantage is its industry-leading hydraulic design, which reduces the circulation pump run time, leading to substantial energy savings and lower operational costs. Additionally, the unit boasts low NOx emissions, making it environmentally friendly and compliant with air quality standards in low-NOx areas. The front-panel-only access and intuitive control pad make the heater easy to operate, service, and maintain, which is a plus for users who prefer straightforward maintenance.

However, there are some considerations to keep in mind. The heater weighs 150 pounds and has dimensions of 33.3 x 32.8 x 30.6 inches, so proper planning for installation space and potential assistance for setup is necessary. In summary, this heater is a solid choice for those looking for an efficient and durable solution for heating their pool or spa, with the convenience of easy maintenance and energy savings.