Inspected Navien NR-240A propane tankless heater. Christian was out previously and could not locate leak. Matt arrived and found leak on the air vent. Currently the tankless is not under warranty for parts. But the heat exchanger still is. Homeowner will look for receipt on when he purchased tankless so we can see if the purchase date is within the warranty period. As of now, we will order the part and contact homeowner once it arrives.