It Has a Flat For a Reason

January 4, 2020

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

#blower motor #CFM #cond fan motor

Check out our most recent video

How to Evacuate an AC system, Full Vacuum Procedure

Our latest Podcast

HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

Chris Hughes and Steve Rogers from The Energy Conservatory discuss TEC’s TrueFlow technology and its crucial role in predicting airflow issues in the sales process, particularly for heat pump retrofits. They explain how the TrueFlow app helps contractors accurately measure both static pressure and airflow in existing systems, enabling them to predict whether proposed equipment changes will work effectively. This is especially vital when considering the growing trend of replacing gas furnaces with heat pumps, as the airflow requirements can differ significantly.

The conversation delves into a detailed example of replacing an 80% efficient 48,000 BTU furnace with a heat pump. They demonstrate how the airflow requirement would nearly double from 652 CFM to 1,200 CFM, potentially causing the static pressure to quadruple due to Fan Law 2 principles. This dramatic increase could lead to significant performance issues if not properly addressed during the system design phase. The experts emphasize that using TrueFlow during the sales process allows contractors to identify potential problems and necessary modifications before installation rather than discovering issues during callbacks.

The discussion also covers the ideal workflow for system assessment and sales, starting with customer comfort evaluation and proper load calculations. It’s important to reduce loads through envelope improvements when possible, particularly in cold climates where heat pump retrofits are becoming more common. Proper system sizing often means going smaller rather than larger, contrary to common industry practices, and the worst HVAC systems are often found in expensive custom homes rather than tract housing.

Key Topics Covered:

TrueFlow technology and its role in system forecasting
Fan Law 2 and its impact on static pressure when changing airflow
Heat pump retrofit challenges and considerations
The importance of accurate load calculations
Dual fuel systems as a solution for cold climates
The relationship between airflow and static pressure
Sales process integration of technical measurements
Common issues with oversized equipment
The importance of envelope assessment
Methods for reducing system loads
Proper duct sizing and modification strategies
The role of proper filter sizing and selection
The benefits of flat-rate pricing for duct modifications
Training resources and support available for TrueFlow users

Check out TEC’s YouTube channel at https://www.youtube.com/@energyconservatory, and you can visit TEC’s website at https://energyconservatory.com/.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium. Subscribe to our podcast on your iPhone or Android. Subscribe to our YouTube channel. Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android.

Search Episodes

How to Predict Air Flow Issues in the Sales Process

11/21/2024

Bryan Orr

MCA is 27 and the Breaker is a 50A – Short #219

11/19/2024

Bryan Orr

Deploying Surge Protection & Voltage Monitoring w/ DITEK

11/14/2024

Bryan Orr

Pumping vs. Compression – Short #218

11/12/2024

Bryan Orr

Building Tech Confidence w/ Refrigeration Mentor

11/07/2024

Bryan Orr

Molecular Transformator – Short #217

11/05/2024

Bryan Orr

Surge Protection Basics w/ DITEK

10/31/2024

Bryan Orr

Q&A – Am I Toxic For Caring? – Short #216

10/29/2024

Bryan Orr

App Based HVAC Learning

10/24/2024

Bryan Orr

Q&A – Apps for Doing Proper Loads – Short #215

10/22/2024

Bryan Orr

Search Results placeholder

Comments

Gabe willard @bryanorr

Thanks I will remember that Mex one I do.

11/4/16 at 11:27 PM

Thanks I will remember that Mex one I do.

John @bryanorr

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.

7/15/17 at 07:58 PM