Propane heat pumps: benefits, use and costs

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Propane heat pumps function in much the same way as the heat pumps that have been in use up to now. They are environmental heaters that draw their energy for heating from environmental energy. The use of the natural and "green" refrigerant propane (R290) makes this climate-friendly heating system even more environmentally responsible.

Viessmann has brought certain components that are necessary for the use of R290 to market maturity in the latest generation of heat pumps. In the following article, we explain why the refrigerant is needed, what benefits it brings and when its use is worthwhile for you.

Switching from synthetic refrigerants to environmentally responsible propane

For a long time, fluorinated hydrocarbons ("F-gases") were used as refrigerants, such as R134a or R410A. They are synthetic refrigerants that are now recognised as harmful to the climate. Their scarcity is regulated in the "F-gas Regulation" (Regulation (EU) No 517/2014 on fluorinated greenhouse gases). The stipulations of the Regulation make the use of harmful refrigerants with a high GWP expensive and uneconomical. Refrigerants with a very high global warming potential are now completely banned. The harm that these synthetic refrigerants can do to the climate may only become apparent at the time of their disposal.

Global Warming Potential (GWP) –– what does it mean?

The Global Warming Potential (GWP) indicates the effect of a greenhouse gas (e.g. a refrigerant) on the climate. The higher the value, the worse the impact. The reference value is CO₂ with a GWP of 1. The climate-friendly refrigerant propane (R290) has a GWP of 3. Refrigerants that have been in use for a long time, such as R410A, have a GWP value of over 2000.

Refrigerant R290 and safety in residential buildings

Propane, like any refrigerant, is subject to special safety requirements. In the case of propane gas, safety has actually been tested very thoroughly. With the help of a prototype, the renowned Fraunhofer Institute were successful in designing an R290 heat pump in 2019 that requires very little refrigerant. By way of background: with a heating output of five to ten kilowatts (kW), which is needed for detached houses, the amount of refrigerant for a heat pump is usually around 80  to 90  grammes. A maximum quantity of 150  grammes must not be exceeded as then, higher safety requirements are imposed. The Fraunhofer Institute's prototype required only 20  grammes of R290 per kilowatt of power.

Heat pumps with R290 also suitable for indoor use

Based on this research, it was possible to bring propane heat pumps for private users in detached houses to market maturity. Thanks to resilient safety concepts and special, innovative heat exchangers, heat pumps with R290 are also well suited to indoor use.

The following aspects are testament to the safety of heat pumps with propane gas:

  • Refrigeration circuit is hermetically sealed and has no contact with the water circuit
  • Low amount of refrigerant in use
  • Mandatory safety distances to cellar doors and light wells
  • Compressors are specially designed so that no propane escapes

Benefits of propane as a refrigerant for heat pumps

The changed requirements for refrigerants based on the F-Gas Regulation have made R290 (propane) a very beneficial refrigerant. This is because heat pumps that use propane as a refrigerant are not affected by the F-Gas Regulation. Thanks to its GWP of  3, it is significantly less harmful to the environment and to the climate. In terms of thermodynamic properties, high efficiency and cost, it is in no way inferior to previous refrigerants. In addition, it is available cheaply around the world.

Good to know: anyone who operates a heat pump with a conventional refrigerant need not worry, they can still be sold. Subsequent refilling during servicing should not pose any problems either, as refrigerants can be easily recycled for reuse. Only newly produced and commissioned units are affected by the aforementioned F-Gas Regulation. And for this, Viessmann offers a well-equipped alternative with its Vitocal range.

Advantages of Vitocal propane heat pumps at a glance:

  • Low running costs due to high efficiency and reliability
  • Flow temperatures of 70  °C at outside temperatures of minus 15  °C
  • Existing radiators can still be used; no conversion to underfloor heating necessary
  • Attractive, high quality design of the indoor and outdoor unit
  • Advanced acoustic design for low operating noise
  • Only 0.52  m² installation area (Vitocal  252-A)
  • Environmentally responsible refrigerant R290 with GWP  =  3
  • Works well in combination with an existing condensing system (Vitocal  250-AH)
  • Easy operation through integrated WiFi interface via ViCare App
  • Closed refrigeration circuit: no refrigeration certificate required for installation  
Vitocal 250-A

Monoblock and split heat pumps for all output ranges

There are scarcely any real limits to the use of propane gas as a refrigerant for heat pumps. Propane heat pumps are available for private use in all output ranges from four to 25  kilowatts. Commercial use from 80  kW heating output is also possible. With its latest generation of Vitocal heat pumps 250-A, 250-AH and 252-A, Viessmann has developed compact and powerful monoblock heat pumps with propane as a refrigerant, in which the entire refrigerant circuit is housed in the outdoor unit.

Heating system modernisation: heat pumps with propane in existing buildings

When it comes to heating system modernisation, the use of R290 as a heat pump refrigerant is no obstacle, but a strong argument in favour. That is, at least so far as the new generation of Viessmann air source heat pumps is concerned. With the new Vitocal  25x-A, heating system modernisation is no problem. The monoblock heat pumps easily reach flow temperatures of 70  degrees Celsius, even at outside temperatures of minus 15  degrees Celsius. This means that existing radiators can continue to be used simply and efficiently. Conversion to underfloor heating is not necessary.  

Propane heat pumps are in no way inferior to environmental heating systems with other refrigerants. Nevertheless, whether or not economical operation makes sense in older buildings, for example, depends on the conditions. Sufficient energy insulation as well as a combination with large heating surfaces is always beneficial when it comes to heat pumps. But the new generation of heat pump, whose environmentally responsible propane refrigerant is only one of its many benefits, offers effective operation even without complete modernisation and in combination with older radiators.  

What always matters is good planning and careful inspection by the heating contractor. He/she can clarify all dependencies on site, recommend optimisation measures and undertake important work during implementation. Looking for an installer for your new heat pump? You can find one here:  find an installer.  

The question of costs: propane makes no difference in terms of price

Whether propane is used as a refrigerant in a heat pump makes no difference in terms of the heating system's purchase costs. Looking at future developments, the reverse is more likely to be the case: if refrigerants with a high global warming potential (GWP value) are used in the future, this will cause more costs and effort in the form of applications in the future as a result of the F-Gas Regulation and the "phase down", i.e. the intended scarcity of these refrigerants. The futureproof refrigerant of choice for heat pumps is therefore R290.

Subsidies for propane heat pumps

Heat pumps qualify for state subsidies in certain countries. Please check with your local authorities.