How To Adjust Blower Speed on a Furnace

When outdoor temperatures drop, you become much more reliant on your furnace, which is the heating unit that provides warm and cozy air when it’s chilly outside. Having a properly working furnace is an important part of staying comfortable during the frigid months. Learn how adjusting the blower speed on your furnace can help it continue to efficiently heat your space. 

Why Would You Need to Adjust the Blower Speed on a Furnace?

There are many reasons you may want to adjust the blowing speed of your furnace, such as:

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  • To increase warm airflow.
  • To reduce warm airflow.
  • To quiet your furnace. 
  • To increase efficiency.

How to Adjust the Blower Speed on a Forced-Air System

When relying on your furnace all winter long, it’s important to have at least some understanding of its mechanics. In order to have your furnace work at its maximum capacity, you need to adjust it to the right blower speed. Follow these steps to get started:

Step 1: Determine What Speed You Want

If you find that your home or office is a bit chilly, you may want to increase the blower speed of your furnace in order to provide better airflow through the entire space. If your furnace is so loud it’s making it hard to concentrate on work or watch your favorite television show, you can decrease your blower speed to quiet the unit. 

Step 2: Create a Safe Workspace

When working with any unit connected to electricity, it’s important to turn off the power to prevent electrocution and damage to your furnace. Once you cut the power, you can remove the cover of your furnace to get access to the control board.

Step 3: Adjust the Pulley on the Blower Drive Motor

Adjusting the pulley on the blower driver motor lets you increase or decrease the blower speed. Refer to your owner’s manual to find out exactly what the pulley and other applicable parts look like. 

When increasing the blower speed, loosen the setscrew a little bit. This is the part that holds the pulley to the furnace’s driveshaft. Turn the pulley one rotation clockwise on the shaft. If you want even more speed, do two rotations. Finish by tightening the setscrew.

To decrease the blower speed, you do the opposite rotation. Slightly loosen the setscrew, and then turn the pulley counterclockwise one or two rotations. After, make sure to tighten the setscrew. 

Step 4: Check the Alignment of Your Motor and Blower Pulley

When your furnace’s motor and blower pulley become misaligned, the unit may not work to its full capacity, making it less efficient and noisier. Check the alignment by using a carpenter’s square to see if the pulley is in a straight line and perpendicular to the motor shaft. 

If you need to fix the alignment, loosen the setscrew in order to move the pulley as needed. On older furnaces, you may find that the setscrew is rusted or stuck, making it hard to loosen. In this situation, you can loosen the motor’s mounting bolts and slide the motor to align the pulleys.

What Are Common Causes of Furnace Issues?

Keeping an eye on your furnace is the main way you can prevent damage from thermal stress, dust, and other factors. These are a few common reasons your furnace experiences issues:

  • Wear and tear: Like any other appliance, a furnace can simply stop working after a while. You may eventually need to replace various parts or the whole unit.
  • Lack of maintenance: Failing to regularly check up on your furnace can cause a wide variety of problems. 
  • Dirty unit: Clogged air filters and a dusty unit can cause many preventable problems. 

Furnace Maintenance Tips

Taking care of your furnace is a crucial part of ensuring it works throughout the colder months. Follow these tips to keep your furnace working properly:

  • Clean your air filter. You can prevent many problems with your furnace by simply keeping its air filters clean. Check on your air filters once a month, and change them when they look dirty. This regular maintenance can keep your furnace running smoothly. 
  • Don’t block your air registers. They are what allow warm and cool air to run through your home or office. Keep furniture and other items off of your registers so air can evenly flow through the space.
  • Keep a tidy furnace area. Along with preventing damage to your furnace, keeping items away from your furnace gives you and a service technician easy access to your system. You should also lightly dust your furnace and vacuum the surrounding area. Once a year, you should clean the flame sensor, which is a thin metal rod in front of the pilot flame.
  • Learn what a working furnace looks like. When you get a new furnace or get your current furnace serviced, thoroughly look over it. You could even take a few pictures. This way, you can tell if anything looks off in the future. 

When Should I Hire a Professional to Look at My Furnace?

Since you may not know the inner workings of your furnace and other electrical systems, it’s usually best to hire a professional. They can assess what’s wrong with your furnace and get it running right in no time. Here are a few common instances when you should hire a professional:

Yearly tuneup

Having a professional tune-up your furnace once a year is the easiest way to ensure it works properly. During their visit, the technician will inspect the unit and complete various maintenance tasks, like:

  • Lubricating the blower motor bearings.
  • Tightening loose ductwork.
  • Replacing or cleaning your air filters. 

Difficult-to-detect problems

It often takes a professional to detect mechanical problems with your unit. With their expertise, they may find the following problems:

  • Coolant leaking from the AC system.
  • Loose blower belt or wiring harness.
  • Ill-fitting firing burners.
  • Blocked condensate drain. 

Worried your furnace isn’t meeting energy standards? Let one of our highly skilled technicians run a diagnostic test to assess the problem. Contact us today to schedule an appointment.