Furnaces are designed to be operated by people who know nothing about their mechanics. When you want heat you simply turn the thermostat up to a higher temperature. This sends a message to the furnace and the gas valve opens. Gas flows through an orifice into the combustion chamber of the furnace where the pilot light ignites it. The temperature in the combustion chamber increases and at a certain point it turns on the fan to distribute hot air into the home. The fan will take a little time to come on after you turn up the thermostat of course.
In the case of later manufactured homes the thermostat will be digital and in older homes it is turned up by pushing a lever clockwise to the desired temperature. For safety reasons the thermostat operates on a 24 volt circuit from the furnace rather than on the standard 120 volts. After some time the home heats to the desired temperature and the thermostat closes the gas valve on the furnace. The gas used may be either natural gas or propane.These require different types of orifice. Installation of the wrong orifice is dangerous and this work should be done only by a professional repair person. For more information about mobile home furnaces see our website Mobile Home Furnaces For information about high efficiency furnaces check this out High Efficiency Furnaces. For information about gettting a new furnace try this Gas Furnace Prices