Abstract R290 (propane) is a famous hydrocarbon substance, but the flammable and explosive characteristics require safety precautions for its use. In fact, R290 is also a refrigerant with low global warming potential (GWP) and excellent thermodynamic properties. However, the application of R290 in split type household air conditioners (STHAC) is hindered by unpredictable gas leakages into the room. This paper evaluates the fire hazard of R290 as a refrigerant in STHAC and provides a new method of installing a solenoid valve near the capillary to reduce the fire risk by decreasing the R290 leaking rate. The approach uses a numerical model to analyze the major parameters effect on the concentration distribution of R290 in the room after leakage from the STHAC indoor unit, as well as a series of experimental tests for verification. The influence of different charge quantities, leakage hole diameters and air flows on the R290 concentration distribution in the room were compared and discussed. The new method was also validated by experiments. The results showed that the fire hazard only occurs during the fast-leaking period and that the most likely flammable region is underneath the location of the leak. In addition, the flammable hazards can be assessed by the huge noise generated by the R290 leakage.