Air Quality And Ducting
How often should you change your air conditioning air filter?
On average you should change your air filter every 1-3 months. It's important to change the filter on a regular basis so the A/C will have proper air flow. Reduced air flow will cause excess wear and tear on the blower motor, return ducting, and on the heat exchanger when running the furnace. There are a few factors that will determine how often you change your filter:
How often you run the HVAC system. Of course, the more you run the air conditioner the more you will have to change the filter.
How dirty the air is. If the home isn't sealed properly or if you often open windows more dirt may be in the air.
What type of filter you are using. Allergy filters will typically need to be replaced more often because they catch more dirt, therefore clogging faster.
Where the location of the return is. The lower the return is to the ground the more dirt will be sucked into the filter.
How often should you have your ducting cleaned?
Most likely never. Overall, I'm not a fan of duct cleaning. If you're considering cleaning your ducting typically the thought process is that you're breathing dust that's coming from the ducting. Consider this, the dust in your ducting can can do two things either accumulate or deplete. If the dust were getting into the air you breath, it would be depleting. And, if the dust was depleting, then how would it accumulate in the first place? So that leaves us with the other option, the dirt just accumulates in the ducting slowly over time and doesn't really effect the air that you breath. The dust that is loosened circulated back into the air and is caught by the air filter. Most homes built after 1980 have plastic flex ducting, the problem with cleaning this ducting is that by the time it gets dirty enough to consider cleaning or about 15 years old, it also can become brittle. Cleaning old brittle plastic ducting can cause damage to the inside barrier of the ducting and is typically not advised. The main type of ducting that I can recommend cleaning is metal hard-pipe ducting that is in the floors. This ducting gets 10x dirtier than ducting in the ceiling and the metal ducting can handle a good cleaning without falling apart. However only 1-5% of homes i come across have metal ducting.
How can I test to see how dirty my ducting is?
The best way to see how dirty your ducting is — is to check the return duct by removing the air filter and taking a moist paper towel and swiping it along the duct-work. The return will always be the dirtiest part of your system. Now, remove a supply register and swipe the inside of the ducting. Most times you will see the supply duct has very little dirt.
I see black streaks coming from the registers what does that mean?
Typically black streaks coming from the registers is an indication that your duct-work is leaking and should probably be sealed / replaced. One common place that your system can be leaking is at the registers. Remove one register and if you see a gap between the register they haven't been sealed yet.
How long does ducting last for?
Plastic flex ducting from the 80's and 90's usually last about 30 years. The newer ducting can last 40+ years. Metal ducting typically found in homes over 30yrs old basically last forever, but isn't very efficient and is often leaking at the seams. Over time the metal ducting may need to be sealed / cleaned. A few benefits of metal ducting is its durability against things like rodents, and it doesn't deteriorate as fast as plastic ducting.