R290 Heat Pumps Explained: The Propane Advantage

R290 is the refrigerant grade of propane — a natural refrigerant that has quietly become the gold standard for modern air source heat pumps. The refrigerant is the working fluid inside the heat pump: it absorbs low-grade heat from the outside air, gets compressed, and releases that heat into your home at a useful temperature.

What makes R290 special is its thermodynamics. It can reach much higher flow temperatures than older refrigerants without a collapse in efficiency, and it does so with a Global Warming Potential (GWP) of just 3. For comparison, R32 has a GWP of around 675 and older R410A over 2,000. R290 is future-proof against every planned F-Gas phase-down — you will never be told your refrigerant is being banned.

Flow temperature. R290 units comfortably deliver 70–75°C flow temperatures. R32 typically tops out around 55–60°C before efficiency drops off, and R410A lower still. Higher flow temperature is the single most important factor for retrofit installations.

Efficiency. At the mild UK temperatures where your heat pump spends most of its life, all three can be efficient — but R290 holds its efficiency far better when the weather turns cold and you actually need the heat.

Environment. GWP 3 (R290) vs 675+ (R32) vs 2,000+ (R410A). A refrigerant leak from an R290 system has a negligible climate impact.

This is the retrofit game-changer. A heat pump heats your home by pushing warm water through your radiators. The hotter that water (the “flow temperature”), the more heat each radiator emits — which means your existing radiators can often stay exactly as they are.

Lower-temperature refrigerants force you to compensate with much bigger radiators, because each radiator emits less heat at 50°C than at 70°C. With an R290 system we can design at a higher flow temperature where sensible, dramatically reducing the number of radiators that need changing. Many of our customers keep most or all of theirs.

We still design for the lowest sensible flow temperature to maximise efficiency — but the point is R290 gives us the headroom to keep your install simple, cheaper and less disruptive.

We install R290 heat pumps as standard, including the Grant Aerona³ R290 and Vaillant aroTHERM plus ranges. A well-designed R290 system routinely achieves a seasonal efficiency (SCOP) of 4.0 or higher — meaning it produces four or more units of heat for every unit of electricity it consumes.

The difference between a good and a poor heat pump install is almost never the box on the wall — it is the design behind it. We carry out a full room-by-room heat-loss survey, size the unit precisely, and commission the weather-compensation curve so the system sips energy rather than gulping it.

Yes. Propane is mildly flammable, which is why R290 systems are engineered and sited to strict F-Gas and MCS safety standards — the refrigerant is fully sealed within the outdoor unit, and the small charge is kept well away from ignition sources. The outdoor siting rules exist precisely so that, in the extremely unlikely event of a leak, the gas disperses harmlessly outside.

Millions of R290 systems operate safely worldwide. As MCS-certified installers, we handle all siting and safety compliance for you as part of the design.