The Inner Workings Of Heating Systems

By Author: William Hauselberg
Total Articles: 816
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Understanding your heating system can seem complicated and overwhelming, but really, the basic principles are quite simple. If you are considering attending HVAC training school, or just want to learn a little more about your heading system, here is some basic information. A heating system can be broken into three components: a source of heat, a circulation method, and a system control.

Creating the Heat

The furnace is powered by a fuel source such as gas or electricity. This fuel is burned to heat air which will then be circulated via ducts or pipes. Some systems heat water instead of air and are called hydronic systems.

Circulating the Heat

There are three common methods of getting the warm air into the home. Warm air is circulated through the house ducts using forced air or gravity systems. Radiant systems are used to circulate hot water or steam.

In a forced air system, a fan is used to blow the hot air through the ducts. As the warm air flows into the rooms, the cooler air is pushed through return ducts back to the furnace. This cold air is heated and the cycle continues.

Gravity ...
... systems are based on the principle that warm air rises. The furnace is situated at or below floor level. As the air is heated, it rises through the ducts into the home. The cold air drops to the floor and sinks through return ducts to be heated.

In radiant systems, a portion of the room is heated, such as the floors or a radiator. In a hydronic radiant system, pipes run through the area or object carrying heated water or steam. In an electric radiant system, an electric current runs through wires, causing them to heat up the wired object or area. As the object heats up, the heat is spread to the surrounding areas.

Controlling the Heat

Heating systems are controlled by thermostats. A thermostat regulates temperatures by turning the furnace off and on.

A non-digital, or analog, thermostat contains a bimetallic strip. Bimetallic means that it is composed of 2 metals which react to temperature changes at different rates. These separate reactions cause the strip to bend. When the temperature cools below the desired setting, the strip will bend and complete a circuit to turn on the furnace. As the temperature rises, the strip bends in the opposite direction. This breaks the circuit and turns the system back off.

A digital thermometer monitors temperatures using devices whose resistance levels vary with changing temperatures, such as thermistors or resistance thermometers. In response to these resistors, the furnace is shut off or on via a relay or other semiconductor device.

Whether you are thinking of attending HVAC technician school, or you just want to know what goes on in your furnace, having a good overview of the inner workings of a heating system is a good place to start.

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