10 Best In Ground Pool Heaters 2025 in the United States

The Aquastrong 75,000 BTU pool heat pump is a powerful choice for both above-ground and inground pools up to 21,000 gallons, making it suitable for larger pools or colder climates where quick heating is needed. It offers a dual-mode system that can heat or cool your pool water, allowing you to swim comfortably almost all year round. One of its standout features is the inverter technology, which adapts energy use dynamically, making it highly efficient—with up to 70% energy savings compared to traditional electric heaters and better efficiency than gas options. This means it can keep your pool warm without drastically increasing your energy bills. It also runs quietly, producing about 53 decibels, roughly the noise of a normal conversation, and includes an automatic defrost function to keep working well in winter. Installation is relatively easy thanks to multiple connection adapters, fitting most pool plumbing setups.

The unit is fairly heavy at 218 pounds, which might require professional help for moving and installation. The upfront cost and the need for a 220V power supply could be factors to consider if your setup isn't already compatible. Its WiFi capability and app control add convenience, letting you adjust settings remotely and monitor energy use. For those looking to extend their swim season efficiently and quietly, this heater provides a reliable solution, especially if you have a mid to large-sized pool and a climate that benefits from both heating and cooling.

The Raypak 266,000 BTU Digital Electronic Ignition Natural Gas Pool Heater is a robust option for heating in-ground pools and spas. It operates on natural gas, making it efficient and suitable for various climates, especially colder regions where quick heating is necessary. With a heating capacity of 266,000 BTUs, it is powerful enough for medium to large-sized pools. The intermittent spark ignition system adds a layer of safety by only igniting when heat is required, which helps in saving energy and reducing operational costs.

The use of space-age materials ensures that the heater does not retain residual heat, allowing for installation without costly heat sinks, which is a significant benefit in terms of maintenance and installation costs. Additionally, the programmable thermostat enhances user convenience by allowing precise control over the pool temperature. However, at 210 pounds, it is relatively heavy and might require professional installation. Being a natural gas heater, it requires a gas line connection, which could be an additional installation consideration.

This heater is designed for outdoor use and is built to withstand various weather conditions, ensuring durability. It is suitable for users looking for a reliable and efficient heating solution for their pools or spas, but it is essential to consider the installation process and operational costs before purchasing.

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.