10 Best In Ground Pool Heaters 2025 in the United States

The Hayward W3H250FDN Universal H-Series 250,000 BTU Natural Gas Pool and Spa Heater is a strong contender for anyone looking to heat an in-ground pool or spa. With a heating capacity of 250,000 BTUs, it is powerful enough to effectively warm large pools. This unit uses natural gas, making it an efficient option that can save on long-term energy costs. Its durable cupro nickel heat exchanger is designed to withstand corrosive conditions, which is beneficial for pools with unbalanced water chemistry.

The heater's hydraulic design aims to save energy by reducing the run time of the circulation pump, adding to its energy efficiency credentials. Additionally, it meets low NOx emissions standards, making it a more environmentally friendly choice. Installation and maintenance are simplified by its front-panel access and intuitive control pad, which users have found user-friendly. However, some may find the initial cost and weight (165 pounds) to be on the heavier and more expensive side. The product dimensions indicate it requires a fair amount of space for installation.

It’s ranked #6 in Swimming Pool Heaters, indicating it’s a popular and well-regarded choice in this category.

The Raypak Heat Pump 8450 Model is a robust option for heating in-ground pools, boasting a heating capacity of 140,000 BTUs. This high capacity makes it suitable for larger pools and quicker heating. The use of a titanium heat exchanger ensures durability and resistance to corrosion, even with harsh pool chemicals, which is a significant advantage for long-term use. Energy efficiency is enhanced by the scroll compressor, which operates quietly and is more efficient than traditional piston compressors. Additionally, the spiral titanium tube further boosts efficiency by reducing deposit build-up and improving heat transfer.

The climate suitability is ideal for areas with moderate climates, as heat pumps generally work best when the air temperature is not extremely cold. Installation and maintenance are facilitated by the off-set 2” PVC union connections, making it relatively straightforward for a professional to install. The powder-coated steel cabinet provides excellent protection against harsh weather and physical damage, adding to the product’s longevity. However, at 422 pounds and dimensions of 47.3 x 38 x 36.5 inches, it is quite bulky, which might pose challenges for initial setup and space allocation.

The cost of operation tends to be lower compared to gas heaters, but it's still essential to consider electricity rates in your area. The upfront price might be on the higher side, but it offers reliability and durability, potentially leading to savings in the long run. This pool heater is a good choice for those prioritizing energy efficiency and durability.