An Overview of How Heating Systems Work
Space heating is the largest energy expense in your home. Understanding how your home heating works can help you get the most benefit from your system in terms of comfort, efficiency and energy cost savings. Here is an overview of the different available systems.
Furnace / Forced air
A central gas heating system relies on a cycle of warming cooler air. The furnace burns natural gas or propane to generate heat in the furnace’s burner. The heat then passes through a heat exchanger. This makes the heat exchanger hot enough to heat the air. Air is directed through return vents into the home’s ductwork and is blown over the heat exchanger where it is warmed. The furnace’s blower then forces the air into the supply ductwork where it is distributed throughout the home via the supply vents.
Similar to furnaces, boilers can use a variety of fuels, including natural gas, propane, heating oil, or electricity. Newer model boilers can be very energy efficient. The biggest difference is that rather than heating air, a boiler heats water. The heated water or steam is distributed throughout the home through a series of pipes. The heat from the water seeps into the house through convectors, cast iron radiators, baseboard radiators or, sometimes, air handlers. Some boilers can provide hot water as well.
Heat pumps take heat from outside and release it inside during the cold months. One of the benefits of a heat pump is that it can operate in reverse in the summer months, taking the heat from inside and releasing it outside in order to cool the home. Air-source heat pumps transfer warmth from the air. Ground-source, also called geothermal, heat pumps rely on warmth from the earth or an underground water source. Both types of heat pumps can be installed in a home with ductwork or can be installed as ductless systems.
Radiant heat systems circulate water as steam or liquid. They are silent and don’t create blasts of air into a room. They warm up the room more slowly than forced air heating systems, but can be more efficient because no heat is lost as the air travels throughout the home’s ductwork. They also tend to be better for people with allergies because without constant air circulation, allergens aren’t stirred up. Radiant heat can be installed with passive solar (the cleanest and least expensive to operate), with a boiler-based system that includes radiant floor heat, or with a baseboard system.
Baseboards that operate exclusively with electricity are typically used as supplemental heat, although they can be installed in every room. As a supplement, for example, a baseboard heater in a bedroom can run at night while the main heating system is at a low temperature setting. Baseboard heat is usually installed below a window. As the cold air falls from the window, it enters the heater through a vent. The air is warmed by metal fins heated by electricity. The warm air rises to heat the room, creating a convection current. Baseboard heaters can also work with water or oil, but still require some electricity to operate.