A furnace works by using natural gas, Propane or fuel oil. When thermostat calls for heat, first is going through all safety checking, then Inducer motor started running, then burners are ignited, then heat exchanger starts warming up and Blower Starts Running blowing heated air through ducts that deliver the hot air to rooms throughout the house registers box to the supply diffuser grilles, supply diffuser could be located, 3 Different Place ceiling, floor, or in the wall. And Return air vents pull stale air into the ductwork so that it can be reheated circulated Back into supply duct. This type of heating system is called a ducted warm-air or forced warm-air distribution system. If you add evaporator coil and condenser outside, then it becomes the central air condition system. Now you have air conditioning in summertime and hitting on wintertime.

Boilers are special-purpose water heaters. boiler systems distribute the heat in hot water, which gives up heat as it passes through radiators or other devices in rooms throughout the house. The cooler water then returns to the boiler to be reheated. Hot water systems are often called hydronic systems. Residential boilers generally use natural gas or heating oil for fuel. In steam boilers, which are much less common in homes today, the water is boiled and steam carries heat through the house, condensing to water in the radiators as it cools. Oil and natural gas are commonly used. boiler uses a pump to circulate hot water through pipes to radiators. Important boiler controls include thermostats, aquastats, and valves that regulate circulation and water temperature. Although the cost is not trivial, it is generally much easier to install “zone” thermostats and controls for individual rooms with a hydronic system than with forced air. Some controls are standard features in new boilers, while others can be added on to save energy.

Heat pumps are just two-way air conditioners. During the summer, an air conditioner works by moving heat from the relatively cool indoors to the relatively warm outside. In winter, the heat pump reverses this trick, scavenging heat from the cold outdoors with the help of reversing valve and electrical heat strips system, and discharging that heat inside the house. Almost all heat pumps use forced warm-air delivery systems to move heated air throughout the house.