A refrigerant gas sensing system of a heating, ventilating, and air conditioning (HVAC) system, wherein the refrigerant gas sensing system is configured to collect a sample from a monitored gas volume, to introduce an ignition source to the sample, to detect an amount of combustion product in the sample after ignition, to determine an amount of leaked refrigerant in the monitored gas volume based on the measured amount of combustion product, and to indicate the amount of leaked refrigerant in the monitored gas volume.