It Has a Flat For a Reason


When tightening down a blower wheel or a fan blade on a motor shaft, ONLY tighten it on the flat of the shaft.

If you have more than one screw but only one flat surface on the shaft, only tighten the one set screw.

Also…

Refrain from over-tightening set screws; they need to bite into the shaft, but you don't need to mangle the poor thing. Setting it on the curve and over-tightening can make it hard or impossible to remove the blade or wheel later. I've seen this several times in high-wall ductless systems: an overtightened or improperly set wheel can make it impossible to remove later. A little grease on the shaft and a carefully tightened screw can make it a lot easier for the next time.

Simple, but important.

—Bryan

Related Tech Tips

The Sneaky Effects of Radiant Heat Transfer
If you've ever sat close to a bonfire on a really cold night, you may have noticed that your face starts to get really warm. The minute you put your hands up and shield your face from the light of the flame, your face cools off almost immediately. That happens because the flame is heating […]
Read more
How to Use a Manufacturer Fan Table and Why They are Important
Many installers and service technicians know how to read and use a manufacturer fan table, but this is a quick review with a few extra tips for newer techs. It’s also a good reminder to senior technicians about how this easy-to-use practice can also be easily abused. At installation, properly setting up airflow is imperative to the […]
Read more
Don't Forget the Suction Filter/Drier
Courtesy of Emerson It is important to have refrigerant that is free from debris and contaminants, and we control these issues on many different fronts. 1. Proper tubing handling preventing copper shavings, dirt, and water from entering while installing. 2. Flowing nitrogen while brazing to prevent carbon build-up. 3. Deep vacuum of 500 microns or […]
Read more

3 responses to “It Has a Flat For a Reason”

  1. Pulling the blower on an AC call after I had an 11 degree split temp had me find an underside of evaporator coil completely blanketed. Would be great if you did a podcast or mention on Evaporator coil cleaning and checking basics.

  2. What is the purpose of the canvas wheel? Is it a dust cover; or is it intended to prevent oil from accumulating on the fan blade?

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

loading

To continue you need to agree to our terms.

The HVAC School site, podcast and daily tech tips
Made possible by Generous support from