The oil filter (found in oil-powered systems only) prevents small impurities from clogging the oil-burner nozzle, which could result in a misfire that shuts down the system. Richard first closes the oil valve, then removes the old filter and replaces it, setting aside the dirty filter to be disposed of according to local hazardous-waste regulations.
Your furnace's flame sensor is essentially a safety mechanism. As a thin metallic rod in front of the flame inside the unit, it's sole purpose is to confirm that your gas valves only open when a flame actually exists to burn that gas. When the flame sensor stop working, on the other hand, gas leaks can occur. To repair your furnace's flame sensor, expect to spend between $80 and $250. Even a full replacement of this part typically does not go above that range.
AAA Heating and Cooling has been the leader in residential and commercial furnace installation, heating services and air conditioning repair for thousands of clients throughout Portland, Beaverton, Hillsboro, Lake Oswego and the surrounding areas for over half a century. As a family-owned Portland, OR business, we offer a variety of services, including the installation of home heating and air conditioning systems, AC and furnace service and repair, duct cleaning as well as a variety of commercial heating and cooling solutions.