Performed heating maintenance 24x25x4 filter is in good shape Aprilaire humidifier #35 water panel in good shape Opened bypass damper for humidifier and set humidity to 5 No water leaks present at this time Pulled and cleaned flame sensor Condensate trap clear Blower clean Burners in good shape Detected a heavy gas leak from the furnace control valve We will return with a new gas valve ASAP Otherwise, furnace is operating normally at this time.