The Basics of Furnace Components

A residential gas furnace relies on different components in order to provide your home with warm air. Many homeowners have at least a passing familiarity with components, such as the heat exchanger or gas valve. However, other furnace components remain shrouded in mystery — at least until something goes wrong.

The more you know about the components in your furnace, the better you’ll be able to recognize problems as they occur. For that reason, a thorough understanding of furnace mechanics will work in your favor. If you would like to learn more about the components of a gas furnace, read on. This article will introduce you to a vital and little-known component — the draft inducer.

Furnace Component Basics

To understand the particular role played by a draft inducer, it will help to refresh your understanding of gas furnace mechanics in general. As gas flows into the combustion chamber through the gas valve, it mixes with a correctly proportioned stream of fresh air. Then, jets of flame come out of the burner assembly, which ignites this mixture.

The resulting combustion generates the heat responsible for warming your home. Depending on how well adjusted the air-to-fuel ratio happens to be, combustion also generates a greater or lesser amount of exhaust gas. Both heat and exhaust flow into the component known as the heat exchanger.

True to its name, the heat exchanger passes the combustion heat through its metal walls to the air that will be circulated throughout your home. The design of the heat exchange process means that the toxic exhaust gases will never actually come in contact with the air of your home. Instead, they flow safely out of your home through the exhaust flue.

The Draft Inducer

While the above explanation may cover the basics, it leaves out the vital role played by the draft inducer. A draft inducer is, in essence, a small fan located inside of the exhaust flue at the far end of a furnace’s heat exchanger. Electrical wires connect this fan to the furnace, such that it will turn on between 30 and 60 seconds before ignition commences.

By turning on before ignition, the draft inducer is able to help suck any lingering combustion gases out of the heat exchanger and send them on their way out of your home. This represents an important safety measure because those gases could potentially ignite if allowed to sit inside the heat exchanger as the furnace’s combustion cycle starts.

Once the furnace has begun its combustion, the draft inducer will continue to run. This allows it to fulfill its important secondary function, which is to ensure an efficient flow of exhaust gases out of the heat exchanger. As a result, combustion can proceed within your combustion chamber. By clearing out exhaust gas, the draft inducer ensures that there will be plenty of clean fresh air to facilitate combustion.

Possible Problems

Most draft inducer problems boil down to one simple thing: the fan won’t spin. As a result, exhaust gases won’t vacate the heat exchanger as quickly as desired. This can put you and your family at risk of substances like carbon monoxide leaking out into your air. It can also reduce your furnace’s efficiency, causing your monthly gas bill to increase.

If you have noticed that your draft inducer has become excessively loud, then it’s likely that something has gone wrong. Either bearings have begun to break down or some sort of blockage is preventing the inducer from spinning. If you believe that your draft inducer has suffered some sort of mechanical issue, then please don’t hesitate to contact the pros at Advanced Heating & Cooling.


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