Stiebel Eltron WPL25A Our opinion on this air water heat pump

We are going to look at the Stiebel Eltron WPL25A outdoor air water heat pump.

Stiebel Eltron Switzerland is a German brand specialized in heat pumps established since 1978 in Switzerland.

After a somewhat difficult start, given the hesitant heat pump market at the end of the 70s and beginning of the 80s, the company has established itself year after year to become a benchmark heat pump supplier with a reputation for quality.

Possibility of obtaining a quotation for a Stiebel, if you are in France in Belgium or Switzerlandby following the few steps below.

The WPL25A model is named after :

  • WP: Wärmepumpe => heat pump in German
  • L : Luft => Air in German
  • 25 : numerical reference of distinction of the model
  • A : Aussen => external in German, to say that it's an external module

Or you'll find this model just about everywhere in Switzerland. Given the brand's presence since the late 70s, there are also many older PAC models that are reaching the end of their life and need replacing.

Installers who pay particular attention to the quality of the products they install, work with Stiebel Eltron.

The model pictured above is a Stiebel Eltron WPL25A air/water heat pump outdoor unit. It contains the entire refrigeration circuit, including evaporator, condenser, compressor and expansion valve. This outdoor unit must be connected via remote pipes to an indoor unit, which stores hot water for domestic use or heating and distributes it throughout the building.

Request a quote for your heat pump installation, France, Belgium.


  • The appearance is modern, with a stylish off-white and chrome-style finish on the top cover and on the front of the fan in front of the evaporator.
  • Stiebel Eltron heat pumps are renowned for their durability. It's not unusual to replace models that were installed in the 90s, i.e. some 30 years ago, and still look very good.


The Stiebel Eltron WPL25A heat pump develops 12.86 kW at -7°C outside and 35°C hot water outlet. A-7/W35. This data is relevant if you are connecting to a low-temperature network such as very low-temperature radiators or underfloor heating. The SCOP is 4.63. This means you produce 4 to 5 times more energy than you consume in electricity.

For an air temperature of -7°C outside and a hot water temperature of 35°C, however, you'll have a COP of 2.93. In winter, energy production is therefore only around 3 times higher than electricity consumption, which is still good, given that -7°C is a rare occurrence throughout the year, and conditions of this kind are not spread out over too long a period.

The maximum water outlet temperature is 65°C... be careful though, for this temperature the official data sheets don't give a COP, but you can guess that it will be rather mediocre, between 1 and 2 (high electricity consumption). The same applies if you decide to connect the heat pump to radiators that require 55°C at the inlet, for example: in this case, the COP data are no longer those given in the technical data sheets. You'll need to ask your installer, who will then ask the manufacturer, Stiebel Eltron.


The WPL 25A has a very good acoustic performance, since on paper it gives 54dBA in sound power and only 32dBA in sound pressure (actually perceived by the ear) at 5m in free field (free field = in the middle of a garden, with no obstacles. If it's on a facade or in a corner, it will be louder).

With this kind of data, we're pretty sure we can pass the noise circle form required by the Commune or Canton for authorization.

Price of a Stiebel Eltron WPL25A

Overall, the price of installing a Stiebel Eltron WPL25A outdoor air-to-water heat pump is around 30-35kCHF. This price includes the material and labor required to install the heat pump, connect it to the electrical network and finally commission the heat pump.

Just the heat pump is around 13kCHF to 15kCHF. Add about 10kCHF for hydraulic and electrical accessories, then 5 to 10kCHF for labor.

You will normally be entitled to assistance for the installation of this heat pump.

Read also: Subsidies in Switzerland for heat pumps


Many installers are absolute fans of the Stiebel Eltron brand. If you're looking for a heat pump in the Geneva area, for example, several local installers work with the brand. If you ask them for a quotation, there's a good chance you'll find the WPL25A or a more or less equivalent model on offer, with all the accessories that go with it.

Few suppliers will allow you to order the machine directly from them, and it's not in your interest to do so, since you'll be paying full price for it, with no discount. Your installer, on the other hand, will benefit from a discount, and may be able to pass this on to you, while leaving himself a margin to live on. It's a win-win situation. So don't call Stiebel Eltron if you're not a professional. Instead, call your installer and tell him you want this model.


A heat pump manager with wall-mounted design box can be delivered with this heat pump, allowing you to finely control the heating and possibly the cooling. This module can be used to control a wide range of functions and, for example, to control 2 heat pumps in cascade. The WPE add-on module can be used to control up to 4 additional heat pumps, and the FET remote control can be used to control all of them.



The Stiebel Eltron WPL25A has a low-profile format that fits neatly under a front window, for example, with a height of 1045mm. The outer block is rather wide at 1490mm: it still fits well under a medium-sized window. The depth of 593mm is standard: don't forget to allow for maintenance space between the block and the wall...at least 30 or 40cm.

See installation instructions for WPL25 A Stiebel Eltron

Finally, the 175kg weight should make your favorite installer's staff suffer during installation. But once you've got past that, the outdoor module won't budge a muscle.

See the dimensions and technical data of the Stiebel Eltron WPL25A heat pump here.

Conclusion on the WPL25A heat pump

The Stiebel Eltron WPL25A is an outdoor air/water heat pump delivering 12.86 kW at -7°C outside and 35°C hot water output. This German-quality product is a must-have in Switzerland for heating your villa in the best possible conditions. The brand's after-sales service offers a wide range of recognized skills to deal with any faults, breakdowns or wear and tear.

This is a product that fits in very well with an underfloor heating system, with above-average thermal performance and pleasant acoustics.

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About the author

Juliena mechanical engineering graduate and specialist in climate engineering since 2009, has become a writer specializing in renewable energies, with expertise in heat pumps and photovoltaic solar panels for individual housing.