Arrived onsite to investigate a no–hot water issue on a propane combi boiler. After speaking with the customer, it was determined that the domestic hot water line had frozen. With the customer’s approval, I attempted to thaw the piping using a heat gun. After approximately one hour with no success, I recommended placing a space heater in the boiler closet. Within a few minutes of running the space heater, hot water was restored. Verified proper system operation and confirmed there were no water leaks at this time.