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ONE CAUSE FOR ICED-UP EVAPORATORS

In the HVACR world, it is not impossible that the designers of a walk-in cooler/freezer to mistakenly chose the wrong FPI (fins per inch) selection for the application you are servicing. Here is a table to reference when you are looking at possible causes of an iced-up coil. With fin spacing too close, frost can easily bridge the gap and quickly reduce air flow through the evaporator.

The proper selection of fins per inch plays a role in maintaining proper humidity levels in the conditioned space as well. The bottom line is this: don’t always assume that the application engineer can’t make a mistake in the selection process. Always look at this factor when troubleshooting your HVACR evaporator problems.

EXCERPT FROM Technical Manual Series available at the ONLINE STORE at RSES.ORG, your HVACR training authority.

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GET READY – CONTROLS COURSE COMING TO NASHVILLE

WATCH FOR NEWS ON THIS AND OTHER UPCOMING EVENTS AT MIDTENNRSES.NET

ONLINE REGISTRATION HAPPENING SOON!

FOR MORE INFORMATION ON HVACR HAPPENINGS, VISIT MIDDLE TENNESSEE RSES HERE

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THE INHERENT PROTECTOR

Suppose you are testing a Copeland 3D (Discus) compressor and your ohmmeter registers OL from line to line on all of the 3-phase legs. The compressor is cold so you determine that the compressor is not off due to an overheat/internal thermostat trip. Your early assessment is that the compressor is bad and must be replaced. You call your supervisor who immediately sees a red flag when you say all 3 windings are open. It may be a defective “inherent protector”. This happened to a service tech that I supervised a few years ago. And it did have a bad protector.  Please see the following photo and wiring diagram for more information on how this all works and the numbers needed to obtain a replacement inherent protector. By the way, this part is located beneath the terminal plate and is mounted just above the motor windings in order to detect the first possible overheat situation.


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MIDDLE TN RSES TO HOST HVACR CONTROLS COURSE

Get ready Nashville for the much anticipated and most requested HVACR training experience.

Continue to monitor this website for information regarding registration for this seminar.


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DANFOSS WINS PRODUCT OF THE YEAR AWARD AT 2018 AHR EXPO

Danfoss, the pioneer of oil-free, magnetic bearing, variable speed technology, was recognized with the prestigious Product of the Year award during the 2018 AHR Expo for its Danfoss Turbocor® TTH/TGH high-lift compressors. 

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A GAME-CHANGING APP

I just can’t say enough about an app that has become an essential part of my life and the overall operation of our HVACR service team.

I am talking about EVERNOTE. It is one of the best ways to assemble, organize and present information that I have ever seen. Now you may be thinking that I am compensated for endorsing this product but you are wrong. I am compensated by using the product. I use it for training purposes as well. It has a great presentation mode that I use instead of powerpoint slides.

I use it many times per day. It is extremely useful when we have our weekly service huddle meeting.

Below is a screenshot sampling one of our huddle meeting frameworks.

You can easily hyperlink the topics to other notes that have been organized into specific Notebooks.

We also have the essential Notebooks shared with all the service techs. It is feature-rich and the beauty is that it syncs across just about all platforms.

An example list of our company shared Notebooks contain the following topics: Work Data, Parts Information, Site Information, Memos, Policies, Training, etc. In these Notebooks are contained over 500 notes and training presentations. It is easily searchable for specific notes inside these Notebooks.

As we go throughout the week and run across some useful topic to discuss or encounter a recurring issue, we add it to the list for “Monday” and we keep the team informed. It helps us to maintain a near-paperless approach to our day to day business practices. For all our larger digital files that contain operation manuals and other manufacturer information, we use Box, which contains over 12GB of technical information for our team to access.

My wife and I both have the premium version and use it for all our financial paperwork and household business. Click here to for a free trial of Evernote.

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THE MOTOR SAVER-PHASE MONITOR

Model 250A is an auto ranging voltage monitor designed to protect 3-phase

motors regardless of size. It is used on 190-480VAC, 50 to 60 Hz motors to

protect the motors from damage caused by single phasing, low voltage,

phase reversal, voltage unbalance, and also high voltage. Added features

include the DPDT contacts that are used to perform two functions when

parameters are exceeded in addition to the standard adjustable restart delay.

 

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TESTING AIR FLOW IN SUPERMARKET CASES

One of the ways to assure that a customer’s case is performing as it should is to test the airflow. One of the best ways to do this is with a test instrument that measures feet per minute as illustrated.

Be sure to measure the airflow at the case discharge air outlet as illustrated below:

The manufacturer recommends that the best time to measure the case airflow is during the warmest time during defrost as the case cycle is terminating.

Below is a manufacturers chart detailing an example of a case specifications including the case design average air flow. Without the proper air flow, the case temperature will not reach the desired set point and the product integrity will suffer.


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HANDS-ON COMPRESSOR TRAINING AT MIDDLE TN RSES

Members and guests got to check a fractional hp compressor for good/bad windings at the June 2017 Regular Monthly Meeting at the Middle TN Chapter. Jayson Goff, CMS was the seminar leader and had just returned from a winning battle over Stage 4 cancer. By the way, the compressor was deemed terminally ill by Larry Lynn, CMS and Doug Drake, CM, due to bad terminals.  😀

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Indoor Air Quality Begins Here

The final factor in evaluating the air distribution in a space is the comfort of the occupants. In general, a person is thermally comfortable when body heat loss equals body heat production. What most people call a “draft” is simply a slight movement of air that results in a local feeling of “coolness.” It has been determined that a velocity change of 15 ft/min has about the same effect on comfort as a 1°F of temperature change. KEEP READING BELOW…..

A typical room air distribution system with local air velocities of less than 40 to 80 ft/min will satisfy 80% of occupants. Localized air temperatures should be less than 2°F below the general room temperature. The temperature near the floor should be less than 4°F below that at about shoulder height. For heating, local air velocities generally are below 40 ft/min. For cooling, local air velocities should be between 40 and 80 ft/min.

EXCERPT FROM “THE TECHNICAL INSTITUTE MANUALS,” available from the ONLINE STORE AT RSES.ORG