CO₂ vs R134a in Heat Pump Hot Water Systems — What Homeowners Should Know
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When deciding to install a heat pump hot water system, a significant decision that you will come across is the selection of the refrigerant. Simply put, CO₂ (carbon dioxide) and R134a are two of the most common options. Each has advantages and disadvantages — and the proper decision is determined by what you consider to be the most important.
What Are CO₂ and R134a Refrigerants?
- R134a — a hydrofluorocarbon (HFC) refrigerant long used in heat pump systems, known for reliable performance and familiarity among suppliers and service technicians.
- CO₂ (carbon dioxide) — a more environmentally friendly refrigerant with a much lower global warming potential (GWP), increasingly used in modern heat pump water heaters designed for efficiency and sustainability.
Performance and Temperature Capability
One of the main differences between the two is how they handle water‑heating demands:
- R134a systems — generally work well for standard hot water needs, but often struggle to reach very high temperatures (above ~60 °C) without an additional heating element for backup. This can be a limitation if you need hotter water for specific uses.
- CO₂ systems — excel in maintaining higher temperatures efficiently. Many CO₂‑based hot water heat pumps can achieve the desired high water temperature in a single pass without needing a backup heater, which improves efficiency and reduces energy use.
This makes CO₂ systems particularly attractive if you prioritise energy efficiency, reliability, and consistent hot-water temperature — even in colder ambient conditions.
Environmental Impact — Why CO₂ Is Often the Greener Choice
R134a has a Global Warming Potential (GWP) that is quite high, thus the worries about the environmental impact in the long run are raised. For home owners who are conscious of their carbon footprint, CO2 is definitely the more eco-friendly refrigerant – giving less environmental impact while still maintaining performance.
Additionally, the emissions savings potential of heat pump hot water systems (mainly those using CO2) over gas or electric resistance systems keeps getting better, as electricity grids are getting cleaner (with more renewables) and thus the overall emissions impact is becoming more and more favourable.What to Consider Before You Choose
When deciding between a CO₂ or R134a hot water heat pump, think about:
- Hot water temperature needs: Do you require water over 60 °C regularly? CO₂ may serve better without a backup heater.
- Environmental priorities: If reducing carbon emissions matters, CO₂ is a strong option.
- System cost and availability: R134a systems are established and widely available; CO₂ systems may be newer and slightly more expensive, but offer long‑term advantages.
- Climate and ambient conditions: CO₂ systems often perform reliably — even in colder conditions — due to their design.
Why The Cylinder Guys Offers Both — And Will Help You Decide
Every house and owner of the house, in our opinion, has different necessities. They are the reason why we offer you to pick between R134a and CO2 heat pump hot water systems, thus making it easy for you to decide which one suits you best (comfort, energy saving, planet, money). We are the ones who ensure that the installation is done by a professional, hence the device will work at its best no matter which refrigerant is used.
Contact us today to discuss which option suits your home best — we’ll help you make an informed and future‑proof choice.
