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R290 vs R32 Heat Pumps: What’s the Difference?
Compare R290 vs R32 heat pumps, including GWP, flammability, siting, efficiency, high-temperature performance, modulation, hot water, F-Gas rules and which suits your home best.
- Last updated: August 2026
- By Phil · Heat Loss Hub
R290 and R32 are both used in modern heat pumps, but they differ significantly in refrigerant climate impact, flammability classification and installation requirements.
That does not mean one refrigerant automatically produces a better heat pump. The complete machine still needs to suit the property heat loss, the outdoor design temperature, the required flow temperature, the available installation location, the heating distribution system, the electrical supply and the hot-water requirements.
KEY TAKEAWAY
Refrigerant should influence the heat-pump decision. It should not replace the heat-pump decision.
R290 vs R32 at a Glance
| R290 | R32 | |
|---|---|---|
| Refrigerant | Propane | Difluoromethane |
| Type | Hydrocarbon | HFC |
| Approx. GWP | Below 3 | 675 |
| Safety class | A3 | A2L |
| Flammability | Higher | Lower |
| Common domestic architecture | Often monobloc | Monobloc or split |
| F-Gas refrigerant | No | Yes |
| High-temperature capability | Common in many current products | Product dependent |
| Efficiency | Product dependent | Product dependent |
| Minimum modulation | Product dependent | Product dependent |
| Sound | Product dependent | Product dependent |
The important distinction is this: the environmental and safety differences come largely from the refrigerant. The performance differences belong to the complete heat pump.
What Is R290?
R290 is refrigerant-grade propane. It is a hydrocarbon refrigerant with an extremely low Global Warming Potential.
Its main characteristics include a very low GWP, an A3 higher-flammability classification, growing use in domestic air-source heat pumps, and common use in modern monobloc designs.
One of its clearest advantages is environmental: R290’s biggest inherent advantage is its extremely low direct refrigerant climate impact. That does not mean an R290 heat pump is automatically more efficient than an R32 heat pump — efficiency depends on the complete machine.
What Is R32?
R32 is difluoromethane. It is an HFC refrigerant that has been widely adopted in heat pumps, air-conditioning systems and refrigeration equipment.
Its GWP is around 675. R32 is classified as A2L, which means it is classed as lower flammability — it should not be described as non-flammable.
R32 has a much higher GWP than R290, but it was already a substantial reduction compared with older R410A refrigerant.
What Actually Changes Because of the Refrigerant?
This is the most useful distinction to make. Some characteristics are directly influenced by the refrigerant itself. Others depend on the heat pump that has been designed around it.
More directly influenced by the refrigerant: GWP, flammability classification, refrigerant handling requirements, F-Gas status, safety-zone requirements, some operating-envelope possibilities.
Not determined by refrigerant alone: COP, SCOP, sound, minimum modulation, maximum useful output, reliability, controls, servicing quality.
Some differences come from the refrigerant. Others come from the machine built around it.
The Environmental Difference
The difference in refrigerant GWP is substantial. R32 has a GWP of approximately 675. R290 has a GWP below 3.
GWP describes the relative warming effect of a refrigerant if it is released into the atmosphere. That means one kilogram of R32 has a much greater direct climate impact than one kilogram of R290 if released.
Refrigerant Charge Matters Too
GWP is only one part of the direct refrigerant impact. The other part is how much refrigerant the heat pump contains. A simplified way to think about it is: refrigerant charge × GWP × amount released.
For illustration only — 2kg R32: 2 × 675 = approximately 1,350kg CO₂ equivalent. 2kg R290: 2 × 3 = approximately 6kg CO₂ equivalent.
This assumes the full charge is released and is used only to demonstrate the scale of the GWP difference. It does not mean a heat pump is expected to leak its full refrigerant charge during normal operation.
Low GWP Does Not Mean Low Running Cost
Refrigerant GWP relates to the direct climate impact of the refrigerant. Your electricity consumption depends on the performance of the complete heating system — including COP, SCOP, flow temperature, emitter sizing, controls, building heat loss and hot-water demand.
An R290 heat pump running unnecessarily at 60°C could consume more electricity than a well-designed R32 heat pump operating at 35°C.
KEY TAKEAWAY
Low GWP reduces direct refrigerant impact. Good system design reduces ongoing electricity use.
Safety: A3 vs A2L
R290 and R32 do not have the same flammability classification. R290 is class A3, meaning higher flammability. R32 is class A2L, meaning lower flammability.
R32 is therefore less readily flammable than R290. But it is not correct to describe R32 as non-flammable. Likewise, it would be wrong to conclude that an R290 heat pump is inherently unsafe. Both refrigerants can be used safely when the product and installation are designed around their individual characteristics.
Why R290 Siting Can Be More Restrictive
Because R290 is more flammable, manufacturers can specify safety zones around parts of the outdoor unit where a refrigerant release could occur. Depending on the exact product, this may affect positioning near openable windows, doors, air vents, drains, gullies, light wells, basement openings, ignition sources and enclosed low areas.
An R290 heat pump may physically fit in a location but still be unsuitable because of its refrigerant safety requirements.
Do Not Use Generic R290 Clearance Rules
There is no useful rule such as “every R290 heat pump must be one metre from a window.” The correct requirement depends on the exact model, refrigerant charge, appliance design, installation geometry and manufacturer instructions. Do not borrow a clearance distance from a different manufacturer or model.
The Four Outdoor-Unit Siting Tests
A heat-pump location should pass more than one test:
- Does it physically fit? Height, width, depth.
- Can it breathe and be serviced? Airflow clearance, front discharge, rear clearance, side access, maintenance space.
- Will the noise be acceptable? Sound power, distance, neighbouring windows, reflections, barriers.
- Is the refrigerant location safe? For R290 in particular: manufacturer safety zones, openings, drains, enclosed spaces, other restrictions.
KEY TAKEAWAY
Planning, airflow, noise and refrigerant safety are separate siting checks.
Do Not Alter the Area Around the Heat Pump Later
A correctly installed heat pump can later be compromised if the space around it is altered — for example installing a close fence, building decking around it, adding a shed, boxing it in, or creating a new enclosed area. These changes can affect airflow, service access, sound and refrigerant safety. An acceptable installation position needs to remain acceptable after the garden or building changes.
R290 vs R32 Is Not the Same as Monobloc vs Split
Many current domestic R290 heat pumps are monoblocs. Many R32 heat pumps are available as monobloc or split. But R290 and monobloc are not synonyms, and R32 and split are not synonyms. Refrigerant and system architecture should be considered separately.
Why R290 Is Common in Monobloc Heat Pumps
In a monobloc system, the refrigeration circuit is normally factory-contained within the outdoor unit, and heating water travels between the outdoor unit and the property. This means normal installation can avoid site-installed refrigerant pipework, which can simplify the refrigerant side of the installation. But it introduces a different consideration: the heating water is now exposed to outdoor conditions.
The Monobloc Trade-Off: Outdoor Water Freeze Protection
Outdoor heating-water pipework needs a suitable freeze-protection strategy — depending on the design, that may include insulation, glycol, antifreeze valves, circulation strategy and power-failure protection. Moving the refrigerant circuit outdoors can simplify refrigerant installation while making outdoor water-pipe freeze protection more important. This is an architecture issue rather than a weakness of R290 itself.
The Split-System Trade-Off
A split system normally carries refrigerant between the outdoor and indoor sections, and the water side can remain primarily indoors. Potential advantages include reduced exposed water pipework and less freeze exposure. But the trade-off is site-installed refrigerant pipework, pipe-length limits, refrigerant handling, and appropriate refrigerant competence.
Monobloc and split systems move different engineering risks to different sides of the wall.
R32 and F-Gas Rules
R32 is an HFC refrigerant and is covered by Great Britain F-Gas controls. This affects how refrigerant equipment is installed, serviced and handled. Where refrigerant work is required, it should be carried out by appropriately qualified personnel.
R32 remains a current refrigerant, but it sits within a regulatory system that is progressively reducing the use of higher-GWP HFCs.
Is R32 Being Banned?
You may see online claims such as “R32 will be banned next year.” That is too simplistic. Great Britain continues to phase down the use of HFC refrigerants, and lower-GWP refrigerants are clearly part of the industry’s future. But restrictions depend on equipment category, refrigerant GWP, date and applicable Great Britain legislation.
Great Britain vs EU Refrigerant Rules
The European Union and Great Britain have separate regulatory regimes. An EU refrigerant deadline does not automatically become the rule for England, Wales or Scotland. Always check current GB requirements when making a purchasing decision.
R32 Was Already a Major Step Down From R410A
For context: R410A has a GWP of approximately 2088. R32 is approximately 675. R290 is below 3. So R32 represented a significant reduction from R410A, and R290 reduces it dramatically further.
Why R290 Is Associated With High-Temperature Heat Pumps
Many current R290 domestic heat pumps advertise maximum leaving-water temperatures of 70–75°C. That can make them attractive for radiator retrofits, domestic hot water, and properties where low flow temperatures are difficult to achieve.
But there is a critical distinction: high-temperature capable does not mean high-temperature should be the design target.
High-Temperature Capable vs High-Temperature Designed
Imagine an R290 heat pump can produce 75°C water but the heating system is designed around 45°C. There is nothing wrong with that — in fact, lower heating-water temperatures will generally improve efficiency. The 75°C capability may simply provide headroom, DHW flexibility, and resilience under unusual conditions.
A heat pump can be capable of high temperatures while spending most of its life operating much lower.
Use the Operating Envelope, Not the Headline Temperature
If the brochure says 75°C maximum flow temperature, ask: at what outdoor temperature? Is that compressor-only? What heating output is available? What COP applies? More detailed technical manuals may contain an operating-envelope chart showing where specific leaving-water temperatures are actually available.
A 75°C headline should send you to the operating-envelope chart, not straight to the radiator schedule.
R290 Does Not Remove the Need for Radiator Design
One of the worst conclusions would be “the R290 heat pump can make 70°C water, so none of the radiators need checking.” That is not a heating design. You still need room-by-room heat loss, radiator output, design flow temperature, return temperature and overall system performance.
An R290 heat pump may allow a difficult radiator system to operate at a higher temperature, but that does not make high-temperature operation as efficient as a well-designed low-temperature system. Capability should not become an excuse to skip design.
R32 Can Still Work Very Well With Radiators
It is equally wrong to assume R32 is only suitable for underfloor heating. Many R32 heat pumps can operate successfully with radiator systems. The key questions are: what flow temperature does the property actually require, what output does the exact heat pump provide at that temperature, what COP does it achieve, and can it cover the design heat loss?
The fair question is not “is it R290 or R32?” It is “what does this exact heat pump do at my design condition?”
Compare Machine Against Machine at the Same Condition
This is the correct way to compare two heat pumps. Suppose your property requires an outdoor design temperature of -3°C and a flow temperature of 50°C. Then compare each product’s output at A-3/W50, COP at A-3/W50, minimum output, sound, and electrical demand.
The fair comparison is machine against machine at the same operating condition.
Worked Retrofit Example
Consider a property with a design heat loss of 8kW, an outdoor design temperature of -3°C, and a required design flow temperature of 52°C. Comparing two fictional heat pumps:
R290 Model A — Output at A-3/W52: 8.7kW. COP: 2.9.
R32 Model B — Output at A-3/W52: 8.2kW. COP: 2.8.
Both may potentially meet the design requirement. The R290 product has slightly more output and slightly higher COP at this particular condition. But the conclusion is not “R290 always beats R32” — it is that this particular R290 machine performs slightly better at this particular design point. The result came from the product data, not the refrigerant label.
When the R32 Product Could Be the Better Fit
Now consider a very different property: a new-build home with a design heat loss of 4kW and a flow temperature of 35°C. The R32 product has a minimum output of 1.0kW; the R290 product has a minimum output of 2.5kW.
Suppose both can comfortably meet the peak heat loss. The R32 product may be able to follow the building’s low heating demand more effectively during mild weather, which may reduce cycling. The refrigerant with the lowest GWP does not automatically create the best system match.
Minimum Modulation May Matter More Than Refrigerant
This is particularly important in new builds, small houses, highly insulated properties, and homes with low-temperature heating. A heat pump that can only reduce to 3kW may struggle to follow a property whose mild-weather load is 800W — even if the heat pump has an extremely low-GWP refrigerant.
For a low-heat-loss home, minimum modulation may affect everyday operation more than whether the refrigerant is R290 or R32.
Is R290 More Efficient Than R32?
Not automatically. Efficiency depends on the compressor, heat exchangers, refrigerant circuit design, controls, fan, flow temperature, outdoor temperature and part-load performance. An excellent R32 heat pump can outperform a poor R290 heat pump at a particular design point, and an excellent R290 product can outperform an R32 product.
You buy a heat pump, not a refrigerant molecule.
Compare COP and SCOP Properly
Do not compare R290 COP at A7/W35 with R32 COP at A-7/W55 — the operating conditions are completely different. Likewise, do not choose whichever brochure shows the highest SCOP without checking water temperature, climate assumption, and actual system design.
Is R290 Quieter Than R32?
Not automatically. Sound is determined by the complete appliance — fan, compressor, casing, control strategy and operating mode. Compare the actual sound data for the exact products, and check whether quiet mode or night mode reduces heating capacity. There is no useful refrigerant shortcut for noise.
Does R290 Defrost Better?
Not automatically. Both R290 and R32 air-source heat pumps use an outdoor heat exchanger that can frost during cold, damp weather, so both need a defrost strategy. The quality of that strategy depends on the heat exchanger, sensors, control logic, refrigerant circuit and product design. Changing refrigerant does not remove the physics of frost formation in cold, damp weather.
R290 vs R32 for Domestic Hot Water
The better comparison is the complete system. Ask: what cylinder temperature can the compressor achieve, at what outdoor temperature, what output is available during DHW, how long does the cylinder take to reheat, and when is the immersion heater required?
The better question is not “which refrigerant gets hotter?” but “which complete system reheats my cylinder efficiently enough?”
High DHW Temperature Can Be a Useful R290 Advantage
Some current R290 heat pumps can achieve relatively high domestic-hot-water temperatures using the compressor, which can provide useful DHW headroom, potentially less immersion-heater reliance, and greater system flexibility. But this must be verified from the actual product data — do not assume every R290 machine behaves identically.
Do Not Assume Every R32 Heat Pump Needs More Immersion
The reverse assumption is also too simplistic. Different R32 products have different DHW operating envelopes, compressor capacities and control strategies. Check the actual hot-water strategy rather than inferring it from the refrigerant type.
Electrical Requirements Can Change the Decision
Two heat pumps that look similar thermally can have very different electrical requirements. Compare maximum current, backup-heater size, single-phase or three-phase supply, simultaneous electrical demand, and protective-device requirements. This can matter if the property already has large loads such as EV charging, an electric shower, induction cooking or battery systems.
The refrigerant debate can become secondary if one product creates a much harder electrical installation.
Size, Weight and Access Matter Too
Heat-pump selection also needs to consider outdoor-unit dimensions, weight, delivery route, base requirements and service clearance. The technically strongest heat pump may not be the easiest product to physically install. Compare the heat pumps you can actually install, not only the ones that look best on paper.
Serviceability Matters
Ask who can service this exact model locally, who provides warranty support, whether engineers are available who understand the refrigerant, how established the manufacturer support network is, and whether spare parts are readily available. R290 servicing requires appropriate competence and equipment for an A3 refrigerant; R32 split-system refrigerant work falls within relevant F-Gas requirements.
The best technical specification is less valuable if there is no practical service support behind the product.
Refrigerant Availability Is Not the Same as Product Support
R290 itself may be widely available, but that does not guarantee access to circuit boards, fan motors, compressors, sensors or proprietary controls. Likewise, future R32 availability is only one part of long-term ownership. Long-term serviceability is usually more about the product ecosystem than the refrigerant itself.
Direct vs Indirect Environmental Impact
It helps to separate two different environmental effects. Direct refrigerant impact relates to possible refrigerant release — R290 has a major advantage here because its GWP is extremely low. Indirect energy impact comes from the electricity the heating system uses over many years, and depends strongly on heat-pump efficiency, flow temperature, controls, heat demand and system design.
KEY TAKEAWAY
Low GWP reduces direct refrigerant impact. Good design reduces lifetime energy use. Both matter.
What Matters Most by Property Type?
| Property or design | Main priorities |
|---|---|
| New build / UFH | Low modulation, W35 efficiency, sound |
| Small insulated home | Minimum output, cycling |
| Existing radiator retrofit | Output and COP at higher flow |
| Tight outdoor location | Safety zone, clearance, noise |
| Split-system preference | Refrigerant pipework and competence |
| High DHW demand | Hot-water output and reheat |
| Limited electrical supply | Maximum current and backup heat |
R290 vs R32 can rank differently depending on the property.
R290 vs R32 Myths
“R290 Is Always More Efficient”
“R32 Is Non-Flammable”
“R290 Heat Pumps Are Unsafe”
“R32 Is Banned Next Year”
“R290 Means I Can Keep Every Existing Radiator”
“A 75°C Heat Pump Should Run at 75°C”
“R290 Means I Will Never Need a Refrigerant Engineer”
“R32 Always Means Split”
“R290 Always Means Monobloc”
“Low GWP Means Low Running Cost”
Which Would I Choose?
There is no universal answer.
I would lean toward the R290 product if: it performs better at the actual design condition; higher-temperature headroom is genuinely useful; the R290 safety zone works at the preferred location; its minimum modulation suits the property; local service support is strong; very low refrigerant GWP is important.
I would lean toward the R32 product if: it performs better at the actual design condition; its lower minimum output suits a low-load property; split architecture solves an installation problem; siting is easier; local support is significantly better; electrical or hydraulic requirements are better suited.
The refrigerant can help break a tie. It should not create the shortlist by itself.
Questions to Ask When Comparing R290 and R32 Quotes
- What exact heat-pump model is being quoted?
- What output does it provide at my outdoor design temperature and flow temperature?
- What COP does it achieve at those conditions?
- What is the minimum thermal output?
- What flow temperature has my heating system actually been designed around?
- Does quiet mode reduce output?
- Does the R290 safety zone affect the proposed location?
- Is the system monobloc or split?
- What freeze-protection strategy is required?
- How will domestic hot water be produced?
- What backup electrical heat is expected?
- Who can service this exact model locally?
You do not need to know the answers before asking. The purpose is to make the design visible.
R290 vs R32 Side-by-Side Comparison Checklist
Product: Exact model, refrigerant, GWP, safety class, monobloc or split.
Design performance: Output at design condition, COP at design condition, minimum output, maximum useful flow temperature, SCOP.
Installation: Safety-zone requirements, sound power, clearances, freeze-protection strategy.
Domestic hot water: Compressor DHW temperature, reheat performance, immersion-heater strategy.
Electrical: Maximum current, backup-heater capacity, single or three phase.
Ownership: Warranty, installer support, local service network, parts support.
This provides a much better comparison than simply asking “which refrigerant is better?”
The Final Heat-Pump Selection Order
- What is the property heat loss? Start with the building.
- What is the outdoor design temperature? Establish the cold-weather requirement.
- What flow temperature is required? This comes from the emitters and room loads.
- What output does the heat pump provide at that condition? Not the model badge — the actual data.
- What is the minimum modulation? How well can it deal with mild-weather loads?
- What is the efficiency? Compare like for like.
- Do the hydraulics work? Flow, pipework, pump head and volume.
- Can it be sited properly? Noise, clearances and access.
- Do the refrigerant safety requirements work? Especially relevant for R290.
- Does the hot-water design work? Cylinder, reheat and controls.
- Does the electrical supply work? Current, backup heat and other loads.
- Is there good long-term support? Warranty, servicing and parts.
KEY TAKEAWAY
Refrigerant belongs in the selection process. It should not replace the selection process.
Final Takeaway
R290 offers a major advantage in refrigerant climate impact and is now used in many capable modern high-temperature heat pumps. R32 remains a proven modern refrigerant used in many efficient heat-pump systems.
Neither refrigerant automatically guarantees better efficiency, lower noise, better modulation, easier installation, or lower running costs. The correct comparison is between complete heat pumps operating at the conditions your home actually requires.
Refrigerant should influence the heat-pump decision. It should not replace the heat-pump decision. And the simplest way to remember it is: you buy a heat pump, not a refrigerant molecule.
GET AN INDEPENDENT DESIGN REVIEW
Two quotes can both look technically impressive while emphasising completely different things. An independent design review compares design-condition output, COP, minimum modulation, radiator requirements, flow temperature, hydraulics, siting, electrical demand and hot-water strategy for your actual property.