R290 propane heat pumps for commercial buildings
An R290 heat pump uses propane as its refrigerant: it has a very low global warming potential but is flammable, so siting and ventilation matter and the manufacturer’s manual is the authority.
What R290 is and why manufacturers use it
R290 is the refrigerant code for propane, a hydrocarbon. It is a natural refrigerant rather than a fluorinated gas, and its global warming potential is very low compared with the hydrofluorocarbon blends that older air-conditioning and heat pump equipment used. That is the main reason manufacturers have moved towards it: as F-gas rules tighten, a refrigerant outside the F-gas family is less exposed to F-gas phase-down and quota rules.
Propane also has useful thermodynamic properties. It can deliver heat at relatively high flow temperatures for an air-source machine, which makes R290 units attractive where existing radiators or fan coils need warmer water. This site has not verified the performance claims of any specific model, so treat the rated figures in a data sheet as the manufacturer’s own claim and ask for the test standard behind them.
Flammability class A3: what it means in general terms
Refrigerants are classed under the ISO 817 and ASHRAE 34 safety system by toxicity and flammability. R290 sits in class A3: low toxicity, higher flammability. In practice this means a leak of refrigerant near an ignition source could ignite, so equipment design and installation aim to stop a leak building up into a flammable mixture.
You will see this addressed in three ways:
- Where the unit goes. Many R290 units are installed outdoors, in the open air, where a small release disperses. Siting near openings into the building, drains, basements, pits or air intakes needs particular care, because propane is heavier than air and can collect in low spots.
- Ventilation and clearances. Manufacturers specify minimum clearances and, for some installations, ventilation or leak-detection arrangements. These are set out in the installation manual and in the relevant equipment standards. This guide does not give figures because they depend on the model and charge.
- Ignition sources. Electrical equipment, other plant and neighbouring activities near the unit may be restricted.
Manufacturers aim to keep the R290 charge low and safety standards limit it, but the charge varies by model and a commercial multi-unit system holds more than a domestic one, so ask for the figure per circuit. Ask the supplier for the charge per circuit and how the design handles it.
UK rules that sit around a flammable refrigerant
Three areas of regulation commonly come up. None of them is a substitute for the manufacturer’s instructions, and a competent designer should be able to say which apply to your site.
- F-Gas. GOV.UK publishes F-gas guidance covering qualifications to work with F gas, leak checking and record keeping. R290 is not an F gas, so these rules apply to the equipment that does use fluorinated refrigerants, but persons working on any refrigeration circuit still need to be competent for the refrigerant in it. Check the current GOV.UK F-gas guidance and ask who will carry out the work and what qualifications they hold.
- DSEAR. The Dangerous Substances and Explosive Atmospheres Regulations 2002 require employers to find out what dangerous substances are in the workplace, assess the fire and explosion risk, put controls in place and classify areas where explosive atmospheres may occur. A flammable refrigerant is a dangerous substance, so a risk assessment is expected. HSE publishes guidance on what employers must do.
- Pressure equipment. Refrigeration circuits can be pressure systems. The Pressure Systems Safety Regulations 2000 place duties on users and owners, including a written scheme of examination for qualifying systems. Whether your equipment qualifies depends on its size and pressure, so ask the supplier.
Building regulations, insurance conditions and fire-safety arrangements for the premises may also have views on flammable refrigerants. Tell your insurer which refrigerant is proposed.
R290 compared with R32 and R744 (CO2)
There is no universally best refrigerant. The comparison below is qualitative.
| Refrigerant | Nature | Safety class | Main trade-off |
|---|---|---|---|
| R290 (propane) | Natural hydrocarbon | A3, highly flammable | Very low GWP and good at warmer flow temperatures; siting and ventilation rules matter |
| R32 | Fluorinated (HFC) | A2L, mildly flammable | Common and widely supported; falls inside F-gas rules and has a higher GWP than propane |
| R744 (CO2) | Natural, non-flammable | A1 | Operates at very high pressure; often suited to high-temperature hot water duties but needs specialist design |
For a typical commercial heating replacement, the choice usually follows the product that fits your flow temperature, site layout and budget, not the refrigerant alone. If you are comparing quotes that use different refrigerants, ask each supplier to explain the safety measures and the long-term refrigerant outlook for that choice.
What to ask a supplier
- Which refrigerant does each unit use, and what is the charge per circuit?
- Where does the manufacturer’s manual allow the unit to go, and what clearances, ventilation or leak-detection does it require on this site?
- Has a DSEAR-style risk assessment been done for the plant, and who holds it?
- Who is competent and qualified to install, commission and service the refrigerant circuit, and how are they evidenced?
- Does the pressure system need a written scheme of examination, and who looks after it?
- Has the proposed refrigerant been disclosed to your insurer, and does the lease or planning position say anything about it?
For installers that can quote, check MCS and other credentials on the public register at mcscertified.com before you sign. For the wider equipment picture, see the commercial air-source heat pump guide and the cost guide.