Induced Draft Blower Motor Maintenance

November 10, 2021

Motor Minute™ Technical Tip – Induced Draft Blower Motor Maintenance

Hi, Chris from Regal Rexnord here with your Motor Minute technical tip. Helping you become an HVAC motor pro one minute at a time.

In this segment we will talk about induced draft blower motor maintenance.

Induced draft blower motor longevity is largely affected by the operating temperature of the appliance. Gas furnaces and package units provide a rated temperature rise (TR) range on their unit rating plates. Temperature rise is calculated by subtracting the measured return air temperature from the measured supply air temperature. The difference between these two values is the temperature rise. Achieving a proper temperature rise can be affected by gas pressure, indoor blower motor airflow adjustments and airside restrictions measured in Total External Static Pressure (TESP).

Always reference the HVAC manufacturer’s manuals for instructions related to how and where to measure temperature rise, adjust gas pressure, adjust indoor blower motor airflow and recommended TESP on each appliance.

In 80% AFUE (Annual Fuel Utilization Efficiency) appliances, the size, length and construction of the vent piping can increase the operating temperature of the induced draft blower motor or cause corrosive condensation in the vent system and the draft blower.

In 90% AFUE (Annual Fuel Utilization Efficiency) appliances, the size, length and construction of the vent piping and intake piping (if applicable) can also increase the operating temperature of the induced draft blower motor or cause excess condensation.

Always reference the HVAC manufacturer’s manuals for instructions related to size, length, construction and materials for vent piping and intake piping (if applicable) on each appliance.

During maintenance and service calls, measuring temperature rise and inspecting vent piping and intake piping (if applicable) will ensure the appliance is operating as designed, improving the longevity and safety of the appliance and its components.

For more information about induced draft blowers and their applications please visit regalmmu.com, select the articles tab and scroll down to find the article titled “Draft Inducers Are All The Same, Right?”.

And that’s a wrap on this segment of Motor Minute technical tips. Remember that we provide motor training and product information in multiple formats including videos, literature, podcasts, articles, of course Motor Minute technical tips and classroom education both online and face to face. All of this industry leading training is available at no charge to HVAC professionals at regalmmu.com. Thank you for taking the time to build your motor knowledge.

Learn more about our FASCO^® draft inducer blowers.