Daikin has launched the Altherma 3 H HT, a pre-engineered air-to-water heat pump using R-32 refrigerant, operating down to −28 C and delivering up to 70 C leaving water temperature for direct boiler replacement in existing radiator systems. The system reportedly achieves a coefficient of performance of 4.86.
Japanese heating system manufacturer Daikin has launched this week a pre-designed residential air-to-water heat pump that installers can reportedly hook into existing plumbing with minimal custom work.
“The Daikin Aletherma 3 H HT provides a distinctively versatile, 3-in-1 ‘plumb-and-play’ solution, that can provide heating, cooling and optional hot water – even in low-ambient temperatures,” the company said in a statement. “Its exceptional adaptability makes it an excellent choice for replacing fossil fuel equipment like boilers, furnaces, and gas domestic hot water.”
The “plumb-and-play” configuration refers to a modular hydraulic configuration where the outdoor unit connects to an indoor hydrobox and existing heating circuits with minimal engineering complexity.
The system is built around a single outdoor unit that can be connected to several indoor configurations, including a wall-mounted hydrobox with an external domestic hot water (DHW) tank, an integrated stainless steel tank in 180- or 230-litre versions, and an integrated thermal tank available in 300- or 500-litre capacities, which can optionally be combined with solar thermal systems.
This modular approach enables installers to adapt the setup to specific requirements for hot water demand, available installation space, and zoning configurations, according to the manufacturer.
The system uses difluoromethane (R-32) refrigerant and is designed to maintain performance even in extreme climates, operating in ambient temperatures down to –28 C, making it suitable for cold-region electrification strategies. It system can reportedly deliver leaving water temperatures up to 70 C, enabling direct compatibility with existing radiator-based heating systems without requiring emitter replacement.
The heat pump utilizes inverter‑controlled compressors and fans to maintain steady comfort while reducing energy use. It operates in three main modes. In heating-only mode, it provides space heating and domestic hot water. In reversible operation, it delivers both heating and active cooling, using fan coils or underfloor systems. In addition, a bi-zone control option is available with integrated tank configurations, allowing independent temperature control across two separate heating circuits.
The outdoor unit measures 1,270 mm x 533 mm x 1,019 mm and is available in power classes of 14 kW, 16 kW and 18 kW. It operates at approximately 38 dB(A) and can purportedly achieve a coefficient of performance (COP) of up to 4.86 at mild conditions and around 2.2 at very high temperature operation.
“The system can connect to emitters already in the home, like baseboards or radiators, integrate with Daikin’s heat pump convectors, or pair with hydronic air handlers and in-floor radiant loops,” Daikin said. “Operating as quietly as a low-library murmur, down to 41 dB(A), the Daikin Altherma 3 H HT is engineered for tranquility. A Low sound mode setting silences sound pressures further, as low as 35 dB(A).”
“The outdoor unit innovatively incorporates an advanced, hidden fan, shaped to minimize the air contact surface, helping to maintain a low sound level,” stated Edwin Reek, Director Water Heating Solutions for Daikin. “To absorb and insulate the sounds made during compressor operation, three layers of insulation surround the compressor, while double sound reduction plates are used between the bottom plate and vibration plate.”
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