duct system inspection

How often should I clean my air ducts?

Man cleaning air ducts with a duct brushYour duct system is the arguably the most important part of your ac system. It is the arteries and veins that deliver air to the rooms in the home. It is imperative that the ducts be clean and well insulated to deliver fresh breathable air to the occupied space. 

To answer the question "How often should I clean my air ducts?" we first have to establish a few things:

1. What type of duct system do you have?

A.) Sheet Metal System

Sheet metal ducting can either be round with interlocking joints, or custom fabricated rectangular ducting that is cut and jointed to fit many different airflow applications needed. Sheet metal is most common in homes built prior to 1980.

Sheet metal ducts are the easiest to clean, because they have smooth inner walls and bends that make it simpler to clean with modern equipment.

B.) Fiber Board System

Fiber board is a rigid fiberglass material that can be cut and shaped to adapt to many different installation applications. Fiber board replaced sheet metal in the 80's and 90's because it was easier to fabricate on site and cheaper than metal. 

Fiber board can be cleaned, but caution is advised because it can become very brittle as it gets older, causing the inside layer to break and flake off when cleaned. This is particularly hazardous because flakes of fiberglass material will be left in the duct system that will not only compromise the integrity of your system, but also distribute fiberglass dust into your rooms. Fiberglass is not healthy to breathe and can cause respiratory issues. 

C.) Flexible Duct System

Flex ducting is the most common type of ducts seen today. It is comprised of a fiberglass layer sandwiched between a thin outer vapor/radiant barrier and a plastic inner flexible lining (where the air travels). It was invented to simplify the installation process in today's complex structures where it would be impossible to use metal or fiberglass duct board. 

Flex ducting is the hardest to clean properly. The reason for this is due to poor installation practices where flex duct is improperly supported/hung causing kinks that make it difficult to run a duct cleaning machine all the way back to the main trunk line. Many duct runs can be in excess of 25', with twists and turns that simply make it impossible to clean adequately. In addition, older flex ducting can become very brittle, which will cause it to break apart and leak into your attic with the slightest touch.  

2. How old is your duct system?

The age of your duct system is very important when it comes to figuring out if it can be cleaned. All types of duct systems become more susceptible to damage the older they get. Also, insulation can degrade or get damaged by pests or animals, making it more efficient to simply replace the ducting as opposed to cleaning it. 

3. How often do you change your filters?

If you have been religious about changing filters at the recommended intervals (see the blog on "How often should I change my filters") then it's likely that your duct system doesn't need to be cleaned. This also depends upon the condition of your duct system (are there holes or damages causing leaks from unwanted sources?). 

4. Do you have microbial growth or excessive dust on the vents?

If you notice mold or dust on your vents, you must identify the source. Many things can contribute to dust and mold growth. The main ones being oversized ac systems or improperly sealed or damaged ducting in the attic space. If you have one of these issues, simply cleaning the ducts will not prevent further issues, just band-aid the problem.

Quality and Detail Matters

If your duct system is in good shape and has been properly installed, then it will be possible to clean it. Choosing the right duct cleaning professional is key to getting it done right. Many companies do duct cleaning as an additional service and don't take the time to do it correctly. Make sure that you monitor their activities and get video footage of YOUR system before and after the cleaning. This will help ensure that you are confident in their service. Don't just pick the cheapest company, because they WILL NOT clean the system properly, and may ignore issues with your system that will continue to plague you with dust and mold problems in the future. 

It is always advisable to get a qualified HVAC professional to inspect your duct system prior to getting it cleaned. It is our responsibility to make sure that you always breathe fresh air in all occupied spaces of your home!   

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