It Has a Flat For a Reason

By January 4, 2020

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

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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.

Phil Barr and Nathan Orr join the podcast to talk about wiring refrigerated cases in commercial spaces, including convenience stores and supermarkets.

Cases may be medium-temp (or high-temp, in some cases) or low-temp. Medium-temp cases can typically defrost on their own during the off cycle, and low-temp cases may have electric or hot-gas defrost to help get ice off the coil at set intervals. Each system has an evaporator (and fans), compressor, condenser, and metering device (often a TXV or EEV), and low-temp refrigeration may have anti-sweat heaters, EPRs, and other components to manage.

Challenges arise when electricians don’t understand the fundamentals of commercial refrigeration, especially as the electrical circuitry relates to the refrigeration circuit components. Time crunches also apply a lot of pressure to electricians and refrigeration technicians. Testing circuits, such as fans and lighting, or using circuit tracers are good ways to get an idea of how an existing system is wired. Labeling wires and breakers and keeping those labels or information in places where others can read them can help you and other electricians in the future.

One of the most common issues happens when technicians or electricians refuse to test out their results to catch their mistakes before callbacks happen. Even seemingly small electrical issues, such as improper lighting, can cause costly losses if product spoils and cannot be sold.

Phil, Nathan, and Bryan also cover:

Changes in central and case control strategies over time
Challenges with retrofits and remodels
Central lighting controls
Mistakes that can be made when labeling wires or breakers
Working against the clock
Terminal blocks, DIN rails, and connectors
Making mistakes and the origin of animosity

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Comments

Gabe willard

11/4/16 at 11:27 PM

Thanks I will remember that Mex one I do.

John

7/15/17 at 07:58 PM

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.

Chris

9/14/17 at 06:01 AM

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?

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