R290 vs. R32 - Which Refrigerant is Better for Heat Pumps?

What is the difference between R290 (propane) and R32?

As the European Union continues to tighten F-Gas regulations, the HVAC industry is shifting toward low-GWP and natural refrigerants. While older refrigerants such as R410A are being phased out and R32 faces increasing regulatory pressure, R290 (propane) is emerging as a preferred alternative.

Why is R290 (Propane) Gaining Popularity? 

• Higher Water Outlet Temperatures 

  R290 allows for higher flow temperatures in heat pump systems 
  

• Low Global Warming Potential (GWP)

  With a GWP of just 3, R290 has almost no environmental impact
  

• Lower Operating Pressures 

  R290 runs at lower pressures, improving safety and system longevity

  
  

Comparison of GWP for different refrigerants

However, R290 is classified as A3 (highly flammable), whereas R32 is classified as A2L (mildly flammable). This means R290 systems require additional safety measures and careful installation to minimize leakage risks.

How is R290 Used in Heat Pumps? 

Most R290 heat pumps store the refrigerant entirely within the outdoor unit, with only water pipes running indoors. This greatly reduces the risk of refrigerant leaks inside the building. Manufacturers also implement additional safety measures, including: 

• Special PCB covers 

• Air-refrigerant separators to ensure safe operation 
  

Below is a comparison of the main technical properties of R290 and R32:

Key Technical Differences: R290 vs. R32 

Property	R290	R32
Critical Temperature	96 °C	78 °C
Critical Pressure	43 bar	58 bar
Latent Heat of Vaporization	425 kJ/kg	380 kJ/kg
Maximum Flow Temperature	Up to 75 °C	Around 60 °C
Operating Pressure at 60 °C	21 bar	39 bar
Operating Pressure at -10 °C	3.45 bar	5.83 bar

What does this mean in practice? 

• R290 can safely achieve higher flow temperatures, making it better suited for radiator systems and colder climates

• R32 reaches its pressure limits at around 60°C, restricting flow temperatures

• Lower pressures in R290 reduce mechanical strain, improving system safety and reliability

• Higher latent heat of vaporization in R290 allows for lower refrigerant charge, reducing system costs

Pressure-enthalpy (P-h) diagram comparison of R32 and R290 refrigerants, highlighting lower operating pressures and improved high-temperature performance of R290 in heat pump applications

R290 Advantages: 

• Higher water temperatures – up to 75°C, even at low outdoor temperatures

• Lower refrigerant charge – reducing CO₂ equivalent emissions

• Lower operating pressures – increasing safety and durability

However, R290 requires stricter safety regulations due to its flammability. 

Although heat pump efficiency is highest at lower flow temperatures, R290’s ability to deliver higher temperatures makes it a perfect solution for flexibility in older buildings with radiator heating systems and for buildings with high DHW demand.

For a more in-depth explanation of how R290 achieves higher temperatures and lower pressures, watch the full video below.

Watch the video