Check your ducts before heating season if you see dust blowing from vents, debris or pest signs in the ductwork, or visible mold near the furnace or registers. Change the furnace filter first. If the ducts are dirty or show growth, have them cleaned before the system runs all winter. Clean-looking ducts usually don't need it.
In Ann Arbor, the first cold night of fall is a little ritual. You nudge the thermostat up, hear the furnace click on for the first time since spring and catch that familiar whiff of warm dust from the vents.
For most homes, that's the start of months of steady heating. From Burns Park to the Old West Side to newer homes across town, your ductwork is about to move a lot of air through every room in the house.
That makes early fall the right time for a quick look. A few minutes now can tell you whether your ducts are fine as they are or whether something needs attention before winter.
Is the burning smell normal when you first turn on the heat?
Usually, yes. Dust settles on the heat exchanger and inside the ducts over the summer. When the furnace fires up, that dust burns off and you smell it. It should fade as the dust burns off.
If the smell lasts longer than that, gets stronger or smells like something electrical or chemical, shut the system off and call an HVAC technician. That's a furnace question, not a duct question.
A musty or damp smell from the vents is different. That can point to moisture in the system, and it's worth a closer look before the heat runs every day.
Do air ducts really need cleaning?
Not on a set schedule. The EPA does not recommend cleaning air ducts routinely, only as needed, and says it isn't a necessary part of yearly heating and cooling maintenance.
According to the EPA, the main reasons to consider it are:
- Substantial visible mold growth inside hard-surface ducts, like sheet metal
- Ducts infested with insects or rodents
- Ducts clogged with excessive dust and debris, or particles blowing out of the supply registers
If none of those apply, your ducts may be fine as they are. A clean filter and a quick visual check can go a long way.
Why does fall matter so much in Ann Arbor?
Southeast Michigan's humid summers are hard on homes. Basements, crawl spaces and air handlers can stay damp for months, and that moisture can settle into the parts of the system closest to the furnace.
Then the season flips. Once the cold sets in, the windows stay shut and the furnace runs day after day. Whatever is sitting in the ducts gets pushed through the house again and again.
Older homes add their own quirks. In an older home, ductwork may have been extended, patched or rerouted through renovations over the years. Some sections run through unfinished basements or tight crawl spaces where moisture and dust collect.
Renovations matter too. If you've done any remodeling in the past year, drywall dust and debris may have found their way into the returns.
What are the signs your ducts need attention?
Walk through the house with a flashlight and look for these:
- Dust puffing out of supply vents when the furnace or fan kicks on
- Heavy dust or debris visible a few inches inside the registers
- Dark spots or fuzzy growth on the register covers, around the furnace or on the air handler
- A musty smell that's stronger when the system is running
- Droppings, nesting material or insect remains in or near the ductwork
- Construction dust in the returns after a recent remodel
- Rooms that get dusty again very quickly after cleaning
One of these on its own might just mean it's time for a new filter. Several of them together, or any sign of mold or pests, is a good reason to have the system looked at.
Your fall checklist before turning on the furnace
Run through this list before the first cold night, or as soon as you can after.
- Replace the furnace filter. A clogged filter makes the system work harder and lets more dust past it. This is the single easiest step.
- Pull off a few register covers. Shine a flashlight inside. Light dust is normal. Thick buildup, debris or anything growing is not.
- Check the return grilles. Returns pull air back to the furnace and often collect the most dust and pet hair.
- Look around the furnace and air handler. Check for moisture, rust, standing water in the drain pan or dark spots on nearby surfaces.
- Inspect exposed ductwork in the basement. Look for disconnected joints, gaps or damp spots, especially on ducts running near the floor or outside walls.
- Clear the area around the furnace. Move stored boxes and anything flammable away so air can move and service is easy.
- Watch for pests. Look for droppings or nesting material near the furnace and in any accessible ductwork.
- Notice the smell on day one. A short burning-dust smell is normal. A musty smell that lingers is worth investigating.
- Schedule furnace service if it's due. An HVAC technician can check the burner, heat exchanger and safety controls. Duct cleaning and furnace service are two different jobs.
What happens during a professional duct cleaning?
A thorough cleaning covers more than the ducts. The EPA says it should cover the supply and return ducts, registers, grilles and diffusers, heat exchangers, heating and cooling coils, condensate drain pans, the fan motor and housing, and the air handling unit housing.
The EPA advises using vacuum equipment that exhausts particles outside the home, or HEPA-filtered equipment if it exhausts inside, so debris doesn't spread through the house. A good company protects your floors and furnishings and shows you what it found.
When you're comparing companies, ask what parts of the system they clean, and how they keep dust contained. The EPA also suggests checking that the company follows the National Air Duct Cleaners Association (NADCA) standards, getting written estimates from at least three providers and avoiding anyone who makes sweeping claims about the health benefits of duct cleaning.
If you know or suspect there's mold in the system, the EPA advises not running it until that's addressed, since running it could spread mold through the house. The moisture behind the mold needs to be found and fixed too.
How do you keep your ducts in good shape all winter?
Once the heating season is underway, a few simple habits help the system stay clean longer.
- Check the filter monthly. Homes with pets, a wood stove or ongoing projects usually need more frequent changes. If the filter looks gray and clogged, swap it.
- Keep registers open and clear. Don't block supply vents with furniture or rugs, and vacuum the covers when you dust.
- Watch basement humidity. Ducts and air handlers in damp basements pick up moisture. The EPA recommends keeping indoor humidity below 60 percent, ideally between 30 and 50 percent, and a dehumidifier helps through the shoulder seasons.
- Seal off work areas during projects. If you're sanding, cutting drywall or tearing out flooring, cover nearby returns and shut the system off while the dust is flying.
- Pay attention to changes. A new smell, a sudden jump in dust or a room that stops heating evenly are all worth a closer look.
Get ready for the heating season
The furnace is about to do a lot of work this winter. If your fall check turned up dust blowing from the vents, debris in the ducts or a musty smell when the heat runs, schedule air duct cleaning with Mold Medics Ann Arbor and start the season with a system you can count on.
