Indoor domestic hot water heat pumps (DHW HPs) using R134A refrigerant have been available for nearly 30 years. Despite this, a portion of models sold in 2025 still utilize R134A. We understand the likely reasons: installers may prefer simplicity, selling models recommended by local brands or those they already stock. Additionally, brands might hold existing R134A model inventory, requiring time and resources for their technical and marketing teams to transition to newer refrigerants.
But does R134A offer any advantage over R290 refrigerant in domestic hot water heat pumps?
If any advantage exists, it boils down to just one: tank water heating time.
However, the difference in heating time is minimal. Consider this comparison based on the European Average Climate zone (as defined by the European government):
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Scenario: Heat pump located in a basement or laundry room absorbing heat from a 7°C ambient source, heating 10°C water.
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Test Standard: EN16147 (target temperature: 53°C).
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R134A DHW HP: Heats water in approximately 9 hours 40 minutes.
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R290 DHW HP: Heats water in approximately 10 hours 10 minutes (a difference of only 30 minutes).
Is a 30-minute difference over 10 hours significant? No, it’s negligible.
Furthermore, considering the R290 models’ ability to achieve higher water temperatures (up to 75°C) and their superior efficiency (leading to lower electricity bills), buyers have compelling reasons to choose R290 over R134A.
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Purchasing an R134A domestic hot water heat pump incurs an additional cost. For an R290 DHW HP model, this extra cost is 0 euros.
This cost difference stems from European regulations. Every air conditioner or heat pump uses refrigerant, each with a Global Warming Potential (GWP) value indicating its contribution to climate change.
Eight years ago, the European government implemented a system charging importers an additional “quota cost” based on the GWP and the amount of refrigerant charged in each unit sold in Europe.
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R134A: GWP = 1430. A typical R134A 300L model contains about 900 grams of refrigerant, equating to 1.287 tonnes of potential CO2. With the CO2 quota price fluctuating (using €15/tonne as an example), importers pay an extra €19.31 per unit, on top of the product cost, shipping, and duties.
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R290: GWP ≈ 3 (virtually zero). European regulations limit the R290 charge in DHW HPs to 152 grams. The calculated CO2 potential is negligible, resulting in no extra quota cost.
Therefore, importers pay nothing extra for R290 models. They also avoid the administrative burden and labor costs associated with logging into the “F-gas portal & HFC licensing system.”
Isn’t this a clear advantage?
The market has already demonstrated that R290 domestic hot water heat pumps are the definitive and optimal solution for European household hot water needs.
Opportunity favors the pioneers; the latecomers risk missing the boat.
VISSPLUS was among the top three manufacturers to develop R290 domestic hot water heat pumps, with thousands of units successfully operating in the market. Our current R290 models represent the 3rd generation of VISSPLUS DHW HPs, incorporating significant features that address long-standing market challenges.
VISSPLUS specializes in customized indoor hot water heat pumps, offering OEM/ODM cooperation solutions.
Contact our management team to learn about the latest features and explore partnership opportunities.
