Ground source heat pumps – even better with propane


13 July 2023

By Alessandro Pinato

One of the biggest macro-trends with regards to heating in Europe is electrification. During renovations and refurbishments inefficient heaters and aging boilers – which produce CO2-emissions and pollution – are gradually being replaced with more modern solutions, like heat pumps. Now, what if a heat pump can lessen the strain on the environment by being the replacement to an older heater or boiler, and leave the fluorinated gases (F-gases) behind in the same go? In the long run, wouldn’t this help the decarbonization of Europe considerably?

Heat pumps are versatile, capable of producing both cooling and heating. They are also very energy efficient compared to traditional heaters, with part of the energy used being transferred from ambient sources in the environment. Further, unlike boilers which often are heated using fossil fuels, heat pumps can be run on electricity from renewable energy sources.

Comparing heat pumps
A particularly interesting type of heat pumps are the ground (or water) source variants. They can make use of ambient energy from a number of external sources, like surface water or underground water. Geothermal energy may also be added to this list of sources. These heat pumps are more efficient than air sourced heat pumps, since they rely on stable temperature sources that are less dependent on weather conditions.

The water source heat pumps are more compact than air source units and are typically installed indoors. This reduces outdoor noise, and has the added bonus of removing any defrosting problems altogether. The heat pumps are capable of producing a wide range of temperature, and can cover many applications – everything from indoor climate comfort heating and cooling to sanitary hot water.

Propane as the refrigerant of choice

Traditionally, some variant of fluorinated gas (F-gas) has been the refrigerant of choice in heat pumps. However, European regulations on the use of F-gas are becoming more and more strict, aiming at reducing the emissions in the atmosphere that are contributing to the negative climate change. Consequently, it is time to consider a new refrigerant, it is time to consider a natural choice. At Swegon, we have chosen propane (R290) as the best option for the future – it occurs in nature, it has a near zero GWP (global warming potential), and it has excellent thermodynamic properties for use in heat pumps. Propane has, to be frank, a potential drawback: it is highly flammable. Is it therefore really safe to use as a refrigerant in indoor installations? The answer is yes, and there is no doubt about it.

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For many years propane is used as refrigerant in many units for outdoor use, for example our Bluebox TITAN Sky and GEYSER Sky heat pump ranges. Providing that the safety standards are followed (in the EU, one of the most important regulations is EN 378 related to “Refrigerating systems and heat pumps”), R290 is perfectly safe to use in indoor installations as well. The units can be installed in standard rooms, with minimal requirements as long as the product has been designed as a ventilated enclosure, with an already on-board safety extraction fan and gas leakage detector.

What is then available?
A perfect example is the new Bluebox SIGMA Zero, a high temperature water source heat pump range that uses R290 as refrigerant. It is a compact and highly efficient heat pump that can serve multiple apartments with heat and domestic hot water, and it is developed for in- and outdoor installation. Even if a water source is not available, it is still possible to combine, in a cascade system, a R290 air source heat pump with a R290 high temperature water source heat pump to supply space heating and domestic hot water in a natural and sustainable way.

 So, when replacing inefficient heaters or aging boilers, consider Sigma Zero, our water sourced heat pumps. Visit our website to learn more. Also, further blog posts about the European F-gas restrictions and propane as a refrigerant.