Stiebel Eltron WPL 25 ACS

Air Source Heat Pump

Cosy warmth from the air, while others turn on their central heating. The WPL 25 ACS air source heat pump, designed for outdoor use, still offers first-class efficiency even at temperatures well below freezing. High flow temperatures mean that conventional radiators can be used.


Stiebel Eltron WPL 25 ACS features include:

  • Air-water heat pump installed outdoors for heating and cooling
  • High efficiency due to demand-dependent control of the inverter compressor
  • Increased efficiency through enhanced saturated vapour injection
  • High coefficient of performance
  • Extremely quiet operation
  • Condensate pan is defrosted efficiently via the refrigerant circuit
  • Time optimised and energy efficient defrosting by reversing the circuit
  • Control via WPM 2.1 or WPM 3 heat pump manager (required accessory)
  • Up to + 65 °C flow temperature possible
  • Low energy consumption due to advanced efficiency technology
  • Versatile combination options with the STIEBEL ELTRON cylinder range

Inverter air source heat pump with output-dependent control, designed as a compact mono block appliance for outdoor installation. Can be used for heating and DHW operation; the AC version also provides efficient cooling via circuit reversal. Suitable for new build and modernisation projects due to high flow temperatures.

Optimised noise reduction due to encapsulated refrigerant circuit and acoustically isolated compressor. The wide gaps between the evaporator fins create low air resistance and, in combination with the modulating fan, result in a low sound power level. The combined enhanced vapour injection/enhanced saturated vapour injection cools the scroll compressor at low outside temperatures, enabling a higher heating output/flow temperature to be achieved. In combination with the ISG (additional accessory), the heat pump controller (required accessory) can be used to control the system via a home network or mobile device. With integral heat and electricity metering via refrigerant circuit data. An emergency/booster heater enables mono energetic operation. The refrigerant circuit is hermetically sealed, tested for tightness at the factory and filled with safety refrigerant R410A.

The waste heat from the inverter is used to raise the return temperature. This increases the overall efficiency of the system. Demand-dependent and energy efficient defrosting through circuit reversal. The condensate pan is heated by the refrigerant circuit to enable efficient defrosting.

Integral anti-vibration mounts for direct connection to the heating system. Pivoting electrical connection panel for better accessibility. Quick access to the condensate pan via cleaning aperture at the rear. The metal casing is corrosion-protected and made from galvanised, powder coated sheet steel, with an alpine white stove enamel finish. The fan grille, recessed grips and cover are made from weatherproof and UV-resistant plastic in aluminium white.

Type WPL 25 ACS
Output @ A2/W35 (EN 14511) 8.33 kW
Output @ A-7/W35 (EN 14511) 12.86 kW
COP @ A2/W35 (EN 14511) 4.14
COP @ A-7/W35 (EN 14511) 2.98


Technical data
Energy efficiency class, heat pump W35 A+++
Energy efficiency class, heat pump W55 A++
Energy efficiency class, composite system (heat pump + controller) W35 A+++
Energy efficiency class, composite system (heat pump + controller) W55 A++
SCOP (EN 14835) 4.53
Cooling capacity @ A35/W7 max. 14.88 kW
Cooling capacity factor @ A35/W7 max. 2.38
Cooling capacity @ A35/W7 partial load 6.76 kW
Cooling capacity factor @ A35/W7 partial load 2.93
Sound Power level (EN 12102) 54 dB(A)
Sound pressure level @ 5m distance in a free field 32 dB(A)
Rated compressor voltage 230 V
Rated voltage, emergency/booster heater 230 V
Max. application limit on the heating side 65 °C
Height 1045 mm
Width 1490 mm
Depth 593 mm
Weight 175 kG

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