I always get the furnace cleaned & checked every year.Change filters
once a month. What I was talking about was cleaning all the duct work
from the furnace that extends throughout the house. With 5 indoor cats
& 2 hairy dogs, my dust bunnies have dust bunnies. No matter how much I run
the vacumn, the dust & hair collects. I've cleaned the grates & what can be
reached with a vacumn hose, but think a whole house cleaning would be
even better.

My quote was from the same company that does the checkups & the same
company where I bought the furnace.