Abstract: Described herein is an apparatus and method for avoiding frost buildup on the air intake and or ice buildup on the ice condensing surfaces of the exhaust vent of a condensing appliance. The apparatus comprises a heat-conducting path that extends between the exhaust gas in the exhaust vent of the appliance, and the frost condensing surfaces at or near the air intake opening of the combustion air vent. The heat-conducting path has a first section in thermal contact with the exhaust gas and a second section in thermal contact with the frost condensing surfaces at or near the air intake. In one configuration, the heat-conducting path is a heat pipe. In one configuration the heat-conducting path is a heat exchanger assembly. The passive transfer of heat energy via the heat-conducting path, from the exhaust gas to the frost condensing surfaces at or near the air intake, avoids frost buildup.