If your home has a modern, high-efficiency furnace, then it's most likely equipped with a draft inducer. This device is a second, smaller blower motor that removes harmful exhaust gases from the unit. As long as your draft inducer is working correctly, it will create negative pressure that forces combustion gases along your exhaust flue and out of your home.
Your draft inducer is a crucial part of your furnace's heating cycle. This component is so vital that your furnace uses a pressure switch to ensure its correct operation. If the pressure switch fails to detect negative pressure from the draft inducer, your furnace will not turn on. Below you will find three potential draft inducer problems that you should watch out for this winter.
1. Pressure Switch Failures
When your thermostat instructs your furnace to turn on, the draft inducer will be the first component to engage. In a typical furnace ignition cycle, the control board will first check that the pressure switch is already in the open position. Once the control board makes this check, it signals for the draft inducer motor to turn on.
After the draft inducer motor engages, the control board checks the pressure switch to confirm that the inducer motor has created negative pressure in the exhaust flue. Failure to indicate negative pressure could be the result of a problem with the inducer motor or exhaust flue, or it could be a problem with the pressure switch itself. In some cases, the tube to the pressure switch can also become clogged.
2. Venting Issues
For the draft inducer to create negative pressure in the exhaust flue, the exhaust plumbing itself must be unobstructed. Since these ducts run outside, they can sometimes pick up yard debris or animal waste. Any obstruction in the exhaust flue will ultimately prevent the draft inducer from pushing combustion gases out of the furnace.
Note that your furnace should always shut down when it detects venting problems. This behavior not only protects you from combustion gases, but it also protects your draft inducer from overheating and damaging itself.
3. Inducer Motor Problems
Draft inducer motors are relatively reliable, but they can fail like any other electronic part. Failing inducer motors often produce a noticeable humming or whining noise when the furnace first turns on. Eventually, the blower motor will fail altogether. When this happens, the pressure switch will no longer detect negative air pressure in the exhaust flue, and your furnace will not turn on.
The draft inducer and venting system in your furnace help to increase the efficiency of your furnace and protect you from harmful combustion gases. If you suspect a problem with any part of this system, always contact a skilled HVAC professional to evaluate your furnace and conduct the appropriate heating repairs.