Common HVAC Problems: Draft Induction Fans

Have you heard strange noises coming from the walls at night? Has the temperature inside your home dropped? You may need help from a professional.

No, it’s not time to call the Ghostbusters, even if what’s happening seems a little spooky. It’s just time to check your draft induction fan. These fans may be a small part of your HVAC system, but they have an outsized impact on how well your furnace functions. In fact, if your draft induction fan goes out, your furnace may not even turn on.

Let’s look at what a draft induction fan is, how you can tell if it needs servicing, and what to do next.

Draft Induction Fans: A Quick Guide

These fans are part of the safety and efficiency upgrades in modern furnaces. They’re intended to help the furnace operate with higher internal air quality and cleaner, more thorough fuel combustion.

What is a draft induction fan?

A draft induction fan, also known as a draft inducer, is a small ventilation fan powered by its own motor (separate from your air circulation blower). It sits near the heat exchanger on your furnace.

This fan kicks on before the furnace lights its burners. It does this to clear out any lingering gasses from the last heating cycle. 

Once the burners are lit, the fan keeps running to provide a steady flow of oxygen to the flame. 

Most furnaces have an air pressure switch that measures the inducer’s output. If the inducer fails to turn on, or isn’t moving a sufficient volume of air, your furnace will likely shut off for your safety until it can be serviced.

How can I tell if my draft induction fan needs service?

The draft inducer is a simple system comprised of a small fan and a motor. As such, the symptoms of trouble may sound like a regular box fan nearing the end of its life. Listen for tapping, clicking or vibrating noises. 

Tapping and clicking might be debris clogging the fan, such as dirt or soot. It might even be the ball bearings in the fan unit coming loose and clicking together. Vibration could mean your motor is unbalanced and knocking into other components within the furnace.

Most furnaces will shut down if they detect a problem with the draft induction fan. But there are other causes that might trigger a shutdown, including a faulty sensor or a blocked exhaust vent. So the most reliable indication that the draft induction fan is in trouble are those spooky noises I mentioned in the introduction.

What should I do if my draft induction fan goes out?

Since the draft inducer system is an important part of your HVAC’s safe and efficient operation, it’s best to leave the final diagnosis and repair to a professional. An HVAC expert can test the draft inducer, see what’s not working, and make the repair.

If you’re concerned about your draft inducer, or any part of your HVAC system, contact Welter Heating today. We’ve been keeping the Twin Cities comfortable in their homes for four generations, and we’re ready to help you, too.