Vitocal 250-A PRO

Vitocal 250-A PRO is a large R290 air-to-water monobloc for larger homes, apartment buildings and commercial applications. Viessmann launched it in the UK in September 2024. The current unit is type AWO-AC-AF 251.A40 and uses a separate indoor hydraulic and control unit.

Output and operating envelope

At A7/W35, Viessmann gives 39.5 kW heating output. Cooling output is 26.0 kW at W7/A35. The maximum flow temperature is 70°C at outdoor temperatures down to -2°C.

The outdoor unit uses one variable-speed scroll compressor and one refrigerant circuit with a 3.3 kg R290 charge. Because R290 is propane, the manufacturer’s safety-area, siting and installation requirements form part of the project design.

Physical and acoustic data

The outdoor unit measures 1,900 mm long, 940 mm wide and 1,570 mm high and weighs 550 kg. These figures make access, foundations, lifting and service clearances material design items.

Viessmann publishes three sound-power values at A7/W55: 58.2 dB(A) ErP, 69.8 dB(A) maximum and 60.9 dB(A) in low-noise mode. They are not sound-pressure levels at a boundary or window, so a site assessment needs the selected operating mode, location and propagation assumptions.

System integration

The unit provides heating and cooling. Hot-water production uses a cylinder-loading arrangement or a compatible fresh-water module. An external heat generator can be integrated for a bivalent design.

The current page describes a planned cascade of up to four outdoor units on one indoor unit, for up to 158 kW. Because it still labels this feature “coming soon”, a project should not assume cascade availability without current written confirmation. Building-management integration uses Modbus TCP/IP or BACnet/IP.

Viessmann’s domestic Vitocal warranty table does not name the 250-A PRO. Its warranty period and conditions therefore come from the terms issued for the project.

Related entries

• Viessmann
• Air-to-water heat pumps
• R290 propane refrigerant
• Acoustic assessment for ASHP