Stiebel Eltron WPL 09 ACS Classic

Air Source Heat Pump - Classic

The WPL 09 ACS classic air source heat pump with inverter technology, basically, heating based on renewable energy with heat, space and price advantages. Much of the necessary system technology is already integrated inside the indoor units. This enables even faster and neater installation.

Stiebel Eltron WPL 09 ACS Classic features include:

  • Compact design.
  • Energy-efficient inverter technology for high flow temperatures even on cold winter days.
  • Suitable for densely built-up areas thanks to low operating noise.
  • Minimal energy consumption – resulting in very low running costs.
  • High energy efficiency class, even at a flow temperature of 55 °C.
  • Eligible for Renewable Heat Incentive (RHI) – providing an even faster return on your investment.

Compact set up
The water heat pump WPL 09 ACS Classic is suitable for detached and semi-detached family homes. The WPL classic is able to utilise waste heat generated when cooling the inverter and as a result of this it will measure the WPL Classic achieves the highest energy efficiency class. The infinitely variable speed adjustment of the fan and the compressor allows the heat pump system to be not only extremely quiet but compact in size saving space in the property.

The WPL classic heat pump is available as a part of perfectly coordinated packs. Depending on the application you can choose between hot water solutions including an option with a space-saving domestic hot water cylinder with an integrated buffer tank. The highly integrated pre-plumbed and pre-wired cylinders are not only space-saving but simple to install, making the installation quicker and easier.


  • Outside air Water heat pump for heating and cooling
  • High efficiency thanks to inverter technology for low energy consumption
  • High DHW comfort due to high flow temperatures
  • Quiet operation thanks to intelligent defrost function
  • Silent mode allows reduced operation for even quieter operation (e.g. at night)
  • Convenient operation via mobile devices in conjunction with the ISG (Internet Service Gateway)
  • Developed and produced in Germany
  • Comes with a free ISG Web Interface, this allows communication with your heat pump remotely via a Smartphone Web app and also allows communication with the Stiebel Eltron Customer Service Centre.
Type WPL 09 ACS Classic
Output @ A2/W35 (EN 14511) 4.5 kW
Output @ A-7/W35 (EN 14511) 4.06 kW
COP @ A2/W35 (EN 14511) 3.72
COP @ A-7/W35 (EN 14511) 2.72


Technical data
Energy efficiency class, heat pump W35 A++
Energy efficiency class, heat pump W55 A+
SCOP (EN 14835) 4.15
Cooling capacity @ A35/W7 max. 3 kW
Cooling capacity factor @ A35/W7 max. 1.62
Cooling capacity @ A35/W7 partial load 1.5 kW
Cooling capacity factor @ A35/W7 partial load 2.38
Sound Power level (EN 12102) 52 dB(A)
Sound pressure level @ 5m distance in a free field 30 db(A)
Rated compressor voltage 230 V
Max. application limit on the heating side 60 °C
Height (mm) 740
Width (mm) 1022
Depth (mm) 524
Weight (kg) 62

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At CVC Direct Ltd we design, deliver and install your complete ventilation project or heating recovery system. Take a look at some of the other ventilation products that we can install in your next home. If you’d like advice on selecting the right home ventilation solution, please get in touch.