Aquatherm Heat Pumps


Back in 1974 two engineers set out to use refrigeration technology to heat a swimming pool economically. They designed and built the first swimming pool heat pump that would heat a pool at a fraction of the cost of conventional gas heaters.

After some research, Calorex concluded that Florida had 3 things that are essential to this technology, lots of swimming pools, mild nighttime temperatures and lots of humidity. Originally they built units in England and shipped them here and in 1978 they started manufacturing swimming pool heat pumps in Ft. Myers, Florida, which is where we are located to this day.

The theory of using refrigeration technology for heating swimming pools was sound, however many of the components available were not. The RX series was engineered as a swimming pool heater as opposed to the assembly of “off the shelf components. The RX series had a vinyl clad cabinet to resist rusting and the evaporator had a special coating to eliminate corrosion.

Calorex invented a timer that was tied to the heat pump’s thermostat and in the event the pool water temperature dropped below the thermostatic setting on the unit it would override the time clock, turn on the heat pump and run until the temperature setting was satisfied.

The “M” series eliminated the metal cabinet and replaced it with fiberglass which solved the rust issue. The evaporator was reconfigured and its size was increased providing more heat and efficiency.

Calorex incorporated technology that would heat a  pool/spa combination with one heater at the touch of a button.

This model increased the heating capacity, efficiency and incorporated programmable digital technology for pool/spa heating functions.

This unit was designed with a plastic cabinet, an oversized evaporator, and a “Scroll Compressor.” The “Scroll” compressor from Copeland replaced the less reliable, less efficient piston compressor. It increased efficiency and reduced noise from the compressor substantially. Electronic dual pool/spa thermostats were standard features eliminating less reliable analog controls.

Back in 1985 Calorex in England spun off Calorex in the USA as a separate company. There was no problem with confusion of the 2 names until both companies put up websites on the Internet. We agreed to start doing business as “Aquatherm Heat Pumps” which ties into our sister company Aquatherm Industries, America’s largest manufacturer of swimming pool solar systems.

This re-engineered line combined all the quality features of the “Premium Series” along with total digital technology. Temperature setting accuracy and reliability is greatly enhanced. BTU output and Coefficient of Performance was increased by more than 10%. Automation for pool/spa combinations was built in, eliminating the need for additional expensive external controls. A remote keypad allowed the pool owner to be able to control the pool temperature and pool/spa functions from a convenient location in the house.

In late 2001 Copeland Corporation responded to the needs for more BTU’s in a swimming pool heater. They made a larger ZR80 Scroll compressor specifically for the use in swimming pool heat pumps. This compressor combined with a larger heat exchanger produces the highest BTU output unit we’ve ever built.

Over the years the pool heat pump industry has gone through a process of eliminating the weakest link. For years Aquatherm has used and still does use marine grade cupronickel heat exchangers. Properly installed and maintained, there have been relatively few failures over the years. Unfortunately, many pool owners do not keep their pool water balanced and that can lead to failure of the heat exchanger. If the heat exchanger is breached and pool water gets in the freon lines, the other two major components, the compressor, and evaporator are compromised as well, in effect ruining the entire machine. The “Titanium Series” utilizes titanium tubing in the heat exchanger which is virtually unaffected by pool water imbalances and carries a 15-year warranty.

With the success of the “AT700 TITANIUM”, we decided to combine the best features in all our units to create our finest pool heat pump ever.  The thought being, if we are going to build a unit with a heat exchanger that could last forever why not incorporate our signature “Mount Holly Gold” polyester-clad evaporator coil into this new model. This exclusive polyester cladding is 10 times as resistant to corrosion as a standard aluminum coil. We used the largest single-phase scroll compressor available for residential use and the largest available titanium heat exchanger which has 85 feet of 5/8” titanium tubing. The cabinet will never rust as it is UV protected ABS plastic and our PC board control technology is the most reliable and accurate control we have ever produced.

With energy prices “going through the roof” Aquatherm set out to maximize the efficiency of our product line. The AT 550 perfectly matches its major components to produce the highest efficiency heat pump we’ve ever produced. In fact, the AT550 cost 7% less to operate than any of our other models and as much as 30% less than some of the less efficient units made by other manufacturers. The BTU output is not as high as some of our other models but the increased efficiency makes it a great choice for your pool heating needs. The AT550 has all the other features of our Titanium Series line including scroll compressor, oversized evaporator coil, titanium heat exchanger, UV protected ABS cabinet and PC board control technology.

 Our new re-engineered units produce more heat per hour and operate at the highest efficiency levels we have ever achieved. Our patented “Thermolink tube in shell” heat exchanger is superior to lower quality heat exchangers and now featured in our entire line of quality pool heat pumps.

 In response to the trend of pool sizes being smaller Aquatherm now has two competitively priced units to address this market. The newly designed units feature microprocessor controlled automatic defrost allows operation down to the mid to lower 40s. New temperature controls have a lockout feature so the only owner can adjust the temperature.

In a never-ending pursuit to increase performance and reliability, Aquatherm once again listened to our customers and have come out with the new “Whisper Heat”. Not only are these the quietest units we have ever built, but we have also again increased efficiency and heat output. All models feature oversized, corrosion resistant evaporator coils, microprocessor controls, titanium heat exchangers, UV protected plastic cabinet and scroll compressors. All of these new features are incorporated in the smallest footprint of any ultra quiet designed pool heat pump. We incorporated an insulated sound barrier to reduce compressor noise and our unique “batwing” fan blade that further reduces noise levels. Our model AT140 produces 132,000 BTU’s with a COP of 6.1. Our titanium heat exchanger is warranted against corrosion for 15 years. The new digital controls have a built-in temperature setting lockout which is ideal for commercial and rental properties.

New touch screen controls have a temperature lockout feature.   All electronics are encapsulated in epoxy, which isolates components and connections from moisture intrusion, which is the cause of 98% of control failures.

The patented Thermolink tube in shell heat exchanger is more efficient and more durable than less expensive tube in tube heat exchangers. The patented hydraulic design adds only 1 PSI at 30 GPM, increasing compatibility with variable speed pumps. Titanium tube heat exchanger is the ultimate protection against corrosion from pool chemical imbalance.

Incorporating a double row evaporator coil with the Thermolink tube in shell heat exchanger, it is our most efficient and highest heat output unit we’ve ever produced.  We also introduced a new cabinet design bringing a fresh new look to our Whisper Heat Line.

In combination with the PoolSync app, you can now control your heat pump through the convenience of your phone. Compatible with all current Aquatherm Whisper Heat heat pump models that feature smart control.

Click Here to Learn More About PoolSync

In 2021, Aquatherm introduced the Whisper Heat AT150 Heat & Cool Model alongside the AT150 Heat Only Model. The new Heat & Cool unit includes a reversing valve that switches from heating mode to cooling mode with the push of a button. The upgraded cooling mode is a refreshing option for unscreened pools that tend to run up to 6 degrees warmer. When paired with the PoolSync smartphone app, you can keep your pool at a consistent comfortable temperature and extend your swim season.

With further innovations of the PoolSync WiFi controller and accompanying app, installation of a PoolSync Relay center will enable full control over your pool equipment all located within one great app. Compatible with units featuring the HP9, HP10, and HP11 controls. For more information, please view our PoolSync page.

Click Here to Learn More About PoolSync