Came out to call for a customer needing a system checked out in a home that belonged to his brother. His brother passed and he had no idea if the system works or not. I checked the system over and found the furnace shut off and the gas turned off. Customer confirmed that the home had propane. I turned the gas on and lit the pilot light. Tried to turn thermostat on, but it wasn’t operating properly. Discussed with customer about repair needed in order to get the system working properly. Customer approved replacement of the thermostat. I changed out the thermostat and made sure wiring was correct. Doublewide has no AC unit. Customer is aware of that and they will look into the possibility of getting a new one installed once they have everything figured out. After installation of thermostat, I turned furnace on and checked operation. Furnace cycled on and off just fine. Heat is operational.