Now that's a great question! The inside of a furnace is pretty complicated from a component standpoint, but the principle of a furnace's operation is very basic.
In order for a furnace to run it must draw in intake air for combustion, evacuate the exhaust gasses created from combustion, ignite the gas, move the warmed air through the home, and dispose of condensation made during the process.
All of these basic furnace functions can be interrupted if annual maintenance is skipped. In other words, as your furnace runs, it is creating problems for itself.
Here are a few examples of common problems solved or avoided by an Austin Plumbing Heating & Air Furnace Tune-up and the technical explanation for why each one occurs
Venting System Block
While a furnace is running in the fall, and while the leaves are falling off the trees, it's very common for a furnace vent to draw in a leaf or two. One or two leaves may not cause much of a problem but if it were to take in one or two every year, the air intake for your furnace will be blocked and cause the furnace to stop running. This can be checked with specialty diagnostic tools or simply taking the vent system apart and visually inspecting it.
Natural gas is a clean burning fuel, but not 100% clean.
As your furnace uses natural gas to run, there is exhaust building up on the ignition components inside the furnace. It may take a year or two, but eventually the residue left behind can coat certain components until they fail, causing the furnace to not work at all.
In addition to ignition system components getting dirty, the furnace burners become clogged with rust and debris during the normal burning process. When this happens, the gas doesn't ignite properly which means you're paying for gas that is never used to heat your home. It just gets blown outside in the exhaust. Cleaning ignition related components and the burners every year will prevent this from happening.
Drain System Clogged
While your furnace is burning gas, it is also making condensation which runs through a drain trap into your home's drain system. In between run cycles, especially in the off season, this water is left to sit stagnant and becomes slimy. As the water evaporates, the slime that is left in the drain tubes dries into hard flakes within the furnace's drain system.
It only takes a few chunks of this furnace sludge to slow down the drain enough for water to leak out of areas of the furnace that shouldn't leak. In many cases, something as simple as a clogged drain can cause much larger problems if the water ends up on the circuit board or another electrical component.
When air movement is restricted through the HVAC system, the internal temperature of the furnace rises. All furnaces have safety switches inside them to prevent the furnace from overheating and causing a safety issue. Air flow can be restricted by dirty filters, undersized ductwork, and/or too many vents being closed in the home. During the tune-up, important air movement readings are taken to verify that your furnace has the proper airflow to cool itself off. If the furnace gets too hot, it will shut down.
All of the situations I mentioned above are some of the most common reasons for "no heat" calls we receive, and all of them are completely avoidable by having your system tuned up each year by an Austin Plumbing Heating & Air expert.
If you encounter a furnace problem this winter and have skipped annual service, no worries...call Austin Plumbing Heating & Air! It's never too early or late to schedule your annual tune-up today...call 262-367-3808.