Will a dirty air system result in higher energy costs?

Dirty Furnace Fan

Good question. Will a dirty air system result in higher energy costs?

The answer is most definitely yes! How much higher depends on several factors including the amount of contamination and its location. More specifically, how many of the air handling components are badly effected by the dirt in the system?

Many times it is all of them. How much money you can save on your energy bills by maintaining a clean HVAC system also depends on several things too, and there is really no cut-and-dry method to figure this out exactly.

Its been said for 30 years or more that even one sixteenth of an inch of soot on the inside or your heat exchanger can increase your energy consumption by up to 10%. That’s because the soot insulates the steel surfaces that are supposed to be transferring the heat produced by the energy to the air that is blowing past it and into your ducts.

The result of this situation is that you need to run your furnace longer to heat your home to its desired temperature.

Most gas furnaces today are high-efficiency models. They have made several amazing changes to HVAC systems over the last 25 years and they are still changing things all the time.

Gas burners are now only about 4″ long and are designed to give you a perfect flame. The perfect flame makes the combustion part of the system run much cleaner. This part of your furnace still does require cleaning and inspection from time-to-time. So instead of the once a year rule that’s been ingrained into many of us, we now recommend to our customers that they have this cleaned once every two years.

Some common sense rules apply to this though… if the furnace is right beside a clothes dryer that doesn’t vent too well, then the furnace will suck in lint. Some basements are just dustier than others. In a case like the one just mentioned, the once per year should still apply. And why would you want your dryer blowing lint into your basement anyway? Dryer duct cleaning should also be a very important part of your home maintenance agenda as well. To learn more about that, check some of our other pages for more information on dryer ducts.

Moving on to the other parts of the HVAC system, the next biggest thief of your heat is your air conditioning coil. If this is dirty then the dust will absorb the heat from the furnace and you will usually smell a slight dust burning smell when your furnace is on.

In severe cases the coil could be so dirty that almost no air is flowing through it. So this absolutely needs to be cleaned whether it looks dirty or not!

Take a closer look at these shots of a dirty air conditioning coil that I pulled out of one family’s furnace. The bottom or underside of this coil is supposed to look like the top. The coil is so plugged that no air was passing through it. The furnace was cycling on limit, meaning that a safety device in the furnace was turning the gas burner off when the temperature inside the furnace kept getting too hot.

Plugged air conditioning coil removed from a residential gas furnace Dirty air system Dirty AC Coil
Photo 1: Plugged air conditioning coil removed from a residential gas furnace
Photo 2: Don’t let dirty coils rob you of your energy dollars!
Photo 3: Absolutely plugged air conditioning coil. No air will flow through this one.

So how does your air conditioning coil get dirty in the first place? All the air that gets blown through the coil comes from the return air part of your duct system. The air must pass through a filter, but how good of a filtration system do you have? And is this filter kept clean all the time?

This is one of the most crucial things that a homeowner can do to maintain their heating or cooling system. Air filters are very, very important to the amount of energy that your system uses, and is also very important to your comfort levels when inside your home.

We didn’t even mention the other components of your HVAC system yet, but it is important to make sure that these are all kept clean too.

These include your air vents and your cold air returns, your tertiary heat exchanger and your furnace fan.

If you are in need of air duct cleaning service then make sure you choose a company who uses compressed air, has knowledgeable technicians, and who will include the cleaning of these crucial HVAC components as part of the job.

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