The short answer
A dusty blower wheel moves less air. With less air going through it, a Northern Virginia furnace runs longer and hotter, the rooms at the far end of the ducts stay cool, and it can shut itself off before the house warms up. Cleaning the wheel fixes that. The heating check is $67 per system through December 31 and measures your airflow. For $229 (regularly $467) we also pull the wheel out of your furnace and clean it blade by blade.
How a little dust costs you airflow
The blower wheel is the drum-shaped fan inside your furnace, the part techs call a squirrel cage. Dozens of small curved blades scoop air and throw it into your ducts, and all the air your furnace heats and your AC cools goes through them.
Dust sticks to the face of those blades and fills the curve. The scoop gets shallower and rougher. The wheel keeps spinning and throws less air with every turn. The dust got there past your filter, through a gap around the edge or a filter changed late. Our furnace filter guide covers picking one that fits.
The $67 Heating Check
We check your furnace, heat pump or boiler before winter. Through December 31. See the offer
Where the 21 percent number comes from
You’ve probably read that a 1/20-inch layer of dust on a blower wheel cuts efficiency by 20 or 21 percent. We went looking for the source. The figure that keeps getting repeated is about coils: 0.042 inch of dirt on a coil, a 21 percent loss, usually credited to the EPA. We couldn’t find the original study, and we couldn’t find anyone who measured it on a blower wheel. For scale, 0.042 inch is a little thinner than a dime, and a credit card is about 0.03 inch.
Dust on the blades does cut airflow, and how much depends on your wheel and how heavy the coat is. That part gets measured in your house with a gauge, which is why airflow is on the heating check.
What a dirty wheel does to your furnace
| What you notice | Why it happens |
|---|---|
| Weak air at the registers, cool rooms at the end of the run | Less air leaves the furnace, and the far rooms feel it first. |
| Furnace shuts off before the house is warm, then starts again | Less air across the heat exchanger lets it overheat, and the high limit switch shuts off the burners. More on short cycling. |
| Longer run times | Moving the same heat takes longer with less air. |
| More fan noise, or a shake you can hear | A variable-speed motor speeds up to hold its airflow, and uneven dust can throw the wheel off balance. |
| An AC coil that ices up in summer | The same wheel runs your cooling. Without enough warm air across it, the coil can freeze. |
A clogged filter causes most of the same signs, and it costs a few dollars to rule out. Change it first.
How to look at yours
- Turn the furnace off at the switch on or near the unit.
- Take off the lower door.
- Shine a flashlight at the blades. You want to see metal and sharp blade edges. Gray or tan felt means it’s due.
- Put the door back on all the way. Most furnaces won’t run until it’s seated.
Leave the wheel where it is. Those small metal clips on the blades are balance weights, and a wheel that goes back out of balance shakes.
What it costs
| Visit | Price | What you get |
|---|---|---|
| The Heating Check | $67 per system | Burners and heat exchanger inspected, electrical tested, airflow measured. We look at the system and tell you what we found. |
| The Blower Wheel Deep Clean | $229, regularly $467 | Everything in the $67 check, plus the wheel out and cleaned blade by blade, a new filter, dampers set for winter and a tune-up. Furnaces only. |
Both run through December 31. If we can’t get the wheel out, you pay $67. Heat pumps have a wheel in the air handler too. The $67 check covers a heat pump, and the $229 price is for furnaces only, so ask us about cleaning one.
Book it
See both visits at goswiftpro.com/furnace-deep-clean, or book the $67 check from goswiftpro.com/cookiesoffer and free MOLTN cookies come with the visit. Every current deal is at goswiftpro.com/offers. Or call (703) 997-9757. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
Does a dirty blower wheel reduce efficiency?
Yes. Dust on the blades cuts how much air the wheel moves, so the furnace runs longer to deliver the same heat. How much depends on the wheel and how heavy the coat is. The 21 percent you see online traces back to dirt on coils, and we couldn’t find a study that measured it on a blower wheel.
How do I know if my blower wheel is dirty?
Turn the furnace off at its switch, take off the lower door and shine a flashlight at the blades. Gray or tan felt in the blades means it’s due. Weak airflow, a furnace that shuts off early and a louder fan are the signs you’d notice first.
How much does it cost to clean a furnace blower wheel in Northern Virginia?
$229 at SwiftPro through December 31, regularly $467. That includes the $67 heating check, the wheel pulled and cleaned blade by blade, a new filter, dampers set for winter and a furnace tune-up. If we can’t get the wheel out, you pay $67.
Can I clean a blower wheel myself?
It’s a big job for a homeowner. You cut the power, disconnect the wiring, pull the blower assembly and take the wheel off the motor shaft. Those small metal clips on the blades are balance weights, and if one comes off the wheel can shake once it’s back in.
How often should a blower wheel be cleaned?
There’s no set schedule. Have it looked at during your yearly furnace service and clean it when dust shows on the blades. A filter that fits and gets changed on time is what stretches the years between cleanings.
