Air to water heat pump with natural refrigerants

Per Henrik Pedersen

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Air to water heat pump with natural refrigerants

Project start March 2019. Ended 2021.

In Denmark, efforts have been made to introduce natural refrigerants instead of HFC refrigerants, which have a high greenhouse effect. It has been successfully implemented in connection with most refrigeration systems, but not in the heat pump area – except in very large plants. In a new project managed by Danish Technological Institute, a new generation of air to water heat pumps using the natural refrigerant propane (R290) will be developed and tested. Among other partners, the project is carried out in collaboration with Nilan – Denmark's largest producer of heat pumps.

Purpose of project
Several conditions make it a good idea to switch to natural refrigerants. Natural refrigerants have virtually no negative effects on global warming or on the ozone layer. In addition, there has been an enormous increase in the price of high GWP refrigerants due to the phase-down of HFCs under the EU F-Gas Regulation. This makes the products more expensive and can prevent the deployment of heat pumps.

In the design of the new propane solution, the highest priority is safety management - both in the manufacturing process and in the end user situation. The challenge is that hydrocarbons - like propane - in contrast to HFC refrigerants are flammable, and therefore a number of safety measures must be taken.

One of Nilan's main products is an air to water heat pump, which is used in low-energy houses providing floor heating. The entire thermodynamic circuit is located outdoors, and therefore this type of heat pump is a good development platform for using propane as a refrigerant.

Today, there are no guidelines for safety management of air to water heat pumps. This will be a generic result of the project that others can benefit from as well. Such guidelines will also help promoting environmentally friendly and efficient propane refrigerant heat pumps.

Achieving a high energy efficiency is central to the project. Propane is an excellent refrigerant with good thermodynamic and thermophysical properties. Specifically, the objective is to increase the energy efficiency by 5-10 % compared to the current HFC solution. The new product must also be in the best energy class (A +++) and live up to the EU Ecodesign requirements.

The project is divided into six phases:

  1. Project management, literature study and mapping of security aspects
  2. Initial selection of components and preparation of simulation model
  3. Analysis of simulation results and determination of final concept
  4. Building and function analysis of Prototype 1
  5. Analysis of results and building and testing of Prototype 2
  6. Final project report and dissemination of knowledge.


  • Danish Technological Institute – Per Henrik Pedersen (project manager)
  • Nilan A/S
  • H. Jessen Jürgensen A/S
  • Vonsild Consulting
  • EBM Papst.

The project is funded by ELFORSK.