Disposable filters

Well most homeowners know there is a filter somewhere in the HVAC system--sometimes they forget about it till things don't work so well. I've had some pull right into the blower of the furnace because they were coated with hair and dirt. Other times on service calls, the homeowner doesn't have a clue where it is. We'll cover placement in another post.
Are the cheap 99 cent filters effective or not?
The fiberglass filters priced usually around 1.00--2.00 will stop most large particles, hair, large drywall particles, and household dust particles. However all heavier finer particles go right through.
For instance fine powdery dirt, pollens, molds, yeast spores go to your HVAC system, and of course gather on ducts, coils, heat exchangers, blowers, etc. The cheaper filters also pass the dirt through when the are full. These need to be changed every 30 days at a minimum.
Next time we'll look at the pleated types.