The furnaces can be divided into four categories hold, industrial, metallurgical, and incinerating. The household furnaces are designed to be installed inside or outside the homes and are mainly used to heat water and keep the homes warm in winter times. Usually, fuels like natural gas, coals, water, and wood are used to run the domestic furnaces.
Gas Furnaces: These days, gas furnaces are the most preferred form of household. These are fueled by natural gas, which can be purchased from a local company. The natural gas is more efficient and more clean burning than most of the other domestic fuels. Generally, gases like liquefied petroleum gas (LPG), biogas, and methane gas are used to fire a gas furnace.
The gases are equipped with an igniter and a thermostat, which senses the room temperature. When the thermostat records a temperature below the programmed temperature, the igniter will turn on and then the furnace will start to burn the gas. Industrial Engineering Book The resultant air will be distributed throughout the house by a duct system. In some gas furnaces, especially in the old ones, the gas is lighted by a pilot light. Most of the newer gas furnaces use an electric spark to ignite the gas.
Oil Furnaces: Many homeowners prefer to use oil furnaces for heating their homes. Oil is the most easily available natural resource whereas the other forms of furnace fuels are not so abundant. However, the oil furnaces are not as efficient as gas furnaces and require more electricity than the gas.
Most oil furnaces have a storage tank from which the oil can be piped into the combustion chamber of the furnace, where it will be atomized. In the oil furnaces, Industrial Development Painting high-voltage electrodes are used to ignite the atomized fuel. The heat is then circulated throughout the house by a forced-air circulating fan.
Wood Furnaces: The wood furnaces use wood pellets or logs to generate heat. Both indoor and outdoor wood furnaces are available in the market. They use either hot water or forced air flow to produce and circulate the heat. Generally, the wood is cheaper than the other furnace fuels and naturally wood furnaces are cost effective than most of the other domestic furnaces. A wood furnace consists of many parts, including a cabinet, sealed firepot, blower, draft fan, thermostat, and a chimney.
All household furnaces, particularly the gas, oil, and wood furnaces, require to be periodically cleaned in order to maintain an efficient heating system. If not maintained properly, these furnaces may emit hazardous fumes. Hence, they should be regularly checked by an experienced professional, at least once in a year. The furnaces that have higher AFUE ratings are more efficient and require much less fuel..
Electric furnaces are also available in the market. The main advantages of electric furnaces are that they are safer than other domestic furnaces and do not produce carbon monoxide or any other hazardous fumes. However, these furnaces are very expensive and it may not be possible for everyone to install an electric furnace in their homes.
Now you have a much better overview on the different types available in the market, hope this helps your decision making.

By master