The heat pump has become central to the journey towards low-carbon buildings. But beneath every efficient heat pump system lies an unsung hero: the refrigerant. It is crucial that specifiers choose the right refrigerant for the right application when aiming to deliver sustainable, compliant solutions. At its core, a heat pump transfers heat from one place to another using a refrigerant cycle. The refrigerant absorbs heat from the source (air, water, or ground) and releases it into the heating system. So, the performance, environmental impact, and even the cost of running the system can hinge on which refrigerant is chosen.
Historically CFCs and HCFCs were used widely, but their high Ozone Depletion Potential (ODP) and Global Warming Potential (GWP) led to their phase-out. Today we have synthetic refrigerants and natural refrigerants, each with their own advantages and drawbacks.
GWP AND LEGISLATION
GWP is the benchmark for assessing a refrigerant’s climate impact, comparing it to CO2 over 100 years. The lower the GWP, the lower the contribution to climate change. The 2014 F-Gas Regulations – and more recently, the EU’s Regulation 2024/573 – are pushing for a refrigerant phase-down, promoting the use of low-GWP alternatives. Compliance with these regulations isn’t optional.
SYNTHETIC OPTIONS
R32 is a popular choice for commercial air source heat pumps. With a GWP of around 675, it’s significantly lower than its predecessors. One of the common misconceptions we hear is that R32 can’t produce high enough temperatures for UK heating demands. That’s simply not true. Most R32 systems can reliably produce flow temperatures up to 55°C, making them suitable for both space heating and hot water in a well-designed system.
NATURAL ALTERNATIVES
Natural refrigerants are attracting more attention, and for good reason. R290 (propane) and R744 (CO₂) boast ultra-low GWP values – just 3 for R290 and 1 for CO₂. This makes them highly attractive from a sustainability standpoint. R290 can deliver temperatures up to 75°C, making it a strong candidate for domestic hot water production and high-demand commercial systems. However, R290 is flammable, which means safety considerations and risk assessments must be built into the design and installation process.
CO2 (R744) heat pumps are especially efficient when operating in a 65–70°C flow/30°C return temperature range. They can accept slightly higher return temperatures, making them adaptable to more varied applications. However, CO2 systems require precise design due to their high operating pressures and transcritical cycle.
PERFORMANCE METRICS
Two key indicators of heat pump performance are the Coefficient of Performance (CoP) and its seasonal variant, SCoP. CoP is the ratio of heat output to electrical input at a specific condition, while SCoP accounts for variations over an entire year.
Natural refrigerants like CO2 can show high SCoP values, particularly in domestic hot water systems. However, achieving this means marrying refrigerant choice with building design, control strategy, and realistic expectations around flow temperatures. A heat pump doesn’t need to match the flow temperature of a gas boiler. Instead, the system should be optimised around what a heat pump can do efficiently. High-temperature outputs are possible, but not always necessary.
COST AND COMPLIANCE
While refrigerant type can influence system cost, natural options like R290 and CO2 are becoming increasingly viable as technology improves and demand grows. Still, system cost isn’t just about the unit – it includes installation, maintenance, training, and compliance with safety standards. It’s also important to consider refrigerant toxicity, flammability, and pressure ratings. For example, while R32 and R290 have some flammability concerns, CO2 systems operate under high pressure, requiring specialised components.
Whether you’re specifying a commercial plant room or retrofitting an older building, your refigerant choice can make or break the system’s performance, environmental impact, and long-term viability. With evolving regulations and growing emphasis on whole-system efficiency, now is the time to brush up your knowledge and explore the full potential of commercial heat pumps in commercial settings. idealcommercialboilers.com