What to know
The part that does most of the work
Change the filter. That is genuinely most of it. A filter is the only thing standing between your ductwork and everything the house puts into the air, and a loaded filter restricts the whole system while letting more past the edges.
How often depends on the filter and the house. A thin one-inch filter in a home with pets may need looking at monthly. A thicker media filter can run several months. The useful habit is checking it rather than trusting the interval printed on the box. If your last filter looks like it has been defending the house since the Clinton administration, that is your answer.
Keep the paths open
- Leave registers open and unblocked, including in rooms you do not use.
- Keep furniture and rugs off supply and return grilles.
- Vacuum the register faces when you vacuum the room. It will not clean the duct, but it keeps what is sitting there from being pulled back in.
- Leave interior doors open where you can, so return air has a way back to the furnace.
What is worth watching for
Ducts rarely fail suddenly. They change slowly, and the signs are easy to miss if nobody is looking for them.
- Airflow at a register that is noticeably weaker than it used to be.
- A room that has started falling behind the rest of the house.
- Visible build-up on the register face or just inside the opening.
- Debris after a remodel, especially drywall dust, which gets everywhere and stays.
- A new whistle or rattle when the system starts up.
What you cannot do from a step ladder
You can clean a register. You can vacuum the few inches you can reach. Neither of those is duct cleaning, and it is worth being clear about the difference rather than feeling like you should have managed it yourself.
A shop vacuum is a fine tool. We own several. It still cannot put a duct system under the steady negative pressure that lets debris further down the run come out rather than move around.
When to have someone look
After a remodel, when you move into a house and have no idea what is in the system, when airflow has dropped and the filter is not the reason, or when you can see build-up you cannot reach. Those are all sensible reasons to have the ductwork looked at.
Wanting it done because a year has passed is not, and we will tell you so. The inspection is free, and sometimes the useful outcome is finding out you do not need us yet.