Refrigerants used in heat pumps
Why heat pumps are harder on the refrigerant
An air conditioner rejects heat to ambient air at perhaps 45 to 55 °C condensing. A heat pump making 60 °C water has to condense above that. The refrigerant has to have usable pressure at that temperature without approaching its critical point, where it stops condensing as a distinct liquid and capacity falls away.
That is the whole selection problem. It is also why a refrigerant that is excellent in an air conditioner can be a poor choice in a hot-water heat pump.
The common fluids
R-32 is the mainstream choice for air-source heat pumps in India, for the same reasons it won in split air conditioners: good efficiency, GWP about 675 against R-410A's 2,088, and a smaller charge for the same duty. It is A2L, so charge limits and handling rules apply.
R-410A remains in a large installed base. Its critical temperature is relatively low, which limits how hot it can usefully run, so it appears more in space heating than in high-temperature water duty.
R-134a has a high critical temperature and holds up well at high condensing temperatures, which is why it appears in commercial hot-water heat pumps and in the high stage of cascade heat pumps.
R-1234ze is the low-GWP HFO for the same commercial territory, with a GWP under 1. It is A2L and has somewhat lower volumetric capacity than R-134a, so machines are designed around it rather than retrofitted to it.
What we do not stock
R-290 (propane) is increasingly used in monobloc heat pumps, factory-charged in small quantities. It is A3, fully flammable, and comes with charge limits and installation rules that are a different discipline. We do not stock it.
R-744 (CO₂) is used in transcritical heat pumps for hot water, particularly where very high water temperatures are wanted. It runs at pressures far above conventional systems and needs purpose-built equipment. We do not stock it.
We would rather name what we do not carry than take an order we cannot fill correctly.
Servicing notes
Heat pumps run more hours per year than a cooling-only system, so leak rates matter more over the life of the machine. They also reverse, which means the circuit sees both directions of flow and the components that manage that, the reversing valve and the check valve arrangement, are common failure points that look like a refrigerant problem at first.
Before adding gas, confirm the machine is actually short of charge rather than failing to reverse properly.
Quick answers
What refrigerant do heat pumps use?
Most air-source units use R-32, with R-410A in the installed base. Commercial and high-temperature machines use R-134a or R-1234ze.
Why does a heat pump need a different refrigerant from an air conditioner?
It condenses at a much higher temperature to make useful heat. The refrigerant must still condense properly at that temperature without approaching its critical point.
Do you supply R-290 for heat pumps?
No. R-290 propane is A3 flammable and normally factory-charged in small quantities under specific installation rules. We do not stock it.
Can I use R-410A in a hot water heat pump?
Its relatively low critical temperature limits how hot it can usefully run, so it appears more in space heating than high-temperature water duty. Follow the machine's design refrigerant.
- ASHRAE Standard 34 · safety classification, A2L and A3 · ashrae.org.
- IPCC Fourth Assessment Report · GWP values used across this site · ipcc.ch.
- IEC 60335-2-40 · charge limits for flammable refrigerants in heat pump and comfort equipment.
This guide is general information compiled from the cited sources — not legal, safety or engineering advice. Read our full disclaimer.
Related: R-32 supply · R-1234ze supply · Why R-32 is replacing R-410A · A2L handling