German HVAC designer and manufacturer Menerga is showcasing a new prototype air-handling unit for public-swimming-pool dehumidification at ISH 2025 that features an integrated CO2 (R744) heat pump.
Besides producing equipment for swimming pools, the company also manufactures air-handling units for commercial and industrial buildings and aquaculture environments. ISH is being held March 17‒21 in Frankfurt, Germany.
“With the CO2 heat pump, we can heat a pool’s air and fresh water supplies and support other heating systems on site, including domestic hot water,” Martin Schramm, R&D at Menerga, told NaturalRefrigerants.com. The new air-handling unit has a 20kW (5.7TR) cooling capacity and a 25kW (7.1TR) heating capacity, with up to 65°C (149°F) outlet water temperatures.
The CO2Compass prototype is part of the company’s ThermoCond series, which also includes a similar air-handling unit with an R410A heat pump. “What’s new is the CO2 refrigerant, making the unit no longer in scope of the EU F-gas Regulation,” Schramm said. He could not specify the development timeline of the unit but indicated that it will be ready for retail sale before the regulation’s 2027 implementation for monobloc equipment.
Operation specifics
Schramm outlined the operational mechanics behind the integrated unit. It includes a microbiologically non-metabolizable polypropylene heat exchanger collecting the latent heat and humidity from the pool hall.
The unit condenses the water vapor collected by the evaporator ‒ dehumidifying the pool hall ‒ and transfers the latent energy with the heat pump to warm the incoming fresh air and water, with leftover heat transferred to other facility systems. Although the air-handling unit is not large enough to meet an entire facility’s heating needs, it can increase overall efficiency by supplementing other systems, according to Menerga.
The new unit, designed for roughly a 20 × 10m (65.6 × 32.8ft) pool, handles a nominal airflow of 5,800 cubic meters per hour (204,825 cubic feet per hour) with a maximum airflow of 9,500 cubic meters per hour (335,490 cubic feet per hour), Schramm explained. The heat pump circuit contains up to 15kg (33lbs) of CO2. “With integrated fresh water heating, the unit can reach a COP of up to 7.1,” he said. The series product will be available with a heating capacity from 14kW (3.9TR) to 90kW (25.6TR) for pool applications and from 10kW to 100kW (28.4TR) of cooling capacity for comfort applications.
“The EU F-gas Regulation motivated us to develop an air handler for public pool and comfort ventilation applications with a natural heat pump,” Schramm said. “We picked CO2 over propane [R290] because of the complications of incorporating a second circuit to deal with R290’s flammability. CO2 allows us to continue using direct expansion and condensation without additional safety requirements.”
According to Schramm, the company plans to roll out the product for new swimming-pool and comfort ventilation applications in the EU, followed by moving it into retrofits. He acknowledged that with the higher operating pressures requiring thicker materials and components for CO2, the new unit will require a higher capital investment than an f-gas equivalent.
