10 Best In Ground Pool Heaters 2025 in the United States

The TURBRO Beluga B75V is a 75,000 BTU inverter heat pump designed for above and in-ground pools up to about 21,100 gallons. It utilizes inverter technology to adjust heating power based on conditions, helping keep your pool temperature stable and saving energy compared to traditional gas heaters. With a high efficiency rating (COP up to 16.2), it can reduce heating costs significantly—up to 40% less than natural gas and 70% less than propane. This makes it a cost-effective choice if you're looking to extend your swimming season in mild to warm climates, ideally when outdoor temperatures stay above 60°F.

The unit won’t heat your pool like a hot tub, but it maintains comfortable temperatures for spring and fall swimming. Its corrosion-resistant titanium heat exchanger also works well with saltwater pools or seaside locations. Installation requires a professional electrician due to its 220-240V power needs, and the system is controlled via a panel or smartphone app for convenience. It may lose some efficiency in colder weather and isn’t suitable for small or inflatable pools because of water flow requirements.

Additional pool accessories like hoses and pumps are not included, which adds to setup costs. If you want a reliable, energy-efficient electric heater to keep a medium to large pool comfortably warm during cooler months, this TURBRO model is a strong option to consider.

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 Hayward W3H400FDN is a natural gas heater designed for in-ground pools and spas, offering a strong heating capacity of 400,000 BTUs. This makes it suitable for larger pools or those in cooler climates where quick and effective heating is important. One of its standout features is the cupro nickel heat exchanger, which is highly resistant to corrosion, helping the unit last longer even if water chemistry isn’t perfectly balanced.

It also has an efficient hydraulic design that cuts down on the pump’s run time, potentially saving money on energy bills. The heater meets low NOx emissions standards, making it better for the environment compared to some older models. Installation and maintenance are made easier thanks to front-panel access and a user-friendly control pad, so operation and servicing are straightforward.

On the downside, with a weight of 195 pounds and fairly large dimensions, it’s a heavy and bulky unit that may require professional installation. While energy savings are mentioned, natural gas heaters generally have higher ongoing fuel costs compared to some electric options. This heater is a solid choice for pool owners who want strong, reliable heating for large or in-ground pools and value durability and ease of use, but should be prepared for higher installation effort and fuel expenses.