Refrigeration and Air Conditioning Mechanic (RAC)

First Period Package (36 Modules) Comments

Date: 12/5/2022 1:29:03 PM
Module: 140101b
Version: 21
Page: 35
Comment: page 35 of 104101b uses a very distorted picture with angles that do not represent the angles at all due to the distortion. The picture is pulled from 140101g page 11
Status: Declined

Date: 12/15/2022 11:59:03 AM
Module: 140101f
Version: 21
Page: 16
Comment: 140101f pg16 under Guardrails, states: "Guardrails must be installed around the working platform on all scaffold installations, regardless of the height from ground level" 140101b pg10 second last paragraph states: "Guardrails must be installed on any temporary work platform that is 3.0 meters or higher" These 2 statements seem either contradictory or confusing at best. (also there is a lot of crossover between 101b, 101f and 101g it would be nice to clean these up)
Status: Implemented

Date: 12/5/2022 1:21:40 PM
Module: 140101k
Version: 22
Page: 14
Comment: In the note section it states to attach a regulator to an acetylene bottle turn the nut counter-clockwise because it uses left-hand threads. I have never seen an acetylene regulator which has left hand threads
Status: Implemented

Date: 12/5/2022 1:25:19 PM
Module: 140101k
Version: 22
Page:
Comment: page 54 question 10 asks how to adjust a flame for soldering. page 10 says the regulator must be at 15psi when in use yet page 54 says adjust the regulator to adjust the flame and the answer for question 10 is adjust the knob on the torch.
Status: Implemented

Date: 6/2/2022 11:53:03 AM
Module: 140102a
Version: 24
Page: 21
Comment: Under figure #2 in the Solution: Cool the Ice : Should be = 1 x 0.5 x (32 - (-40)) = 36 (The 40 is currently missing its negative sign) Cool the Steam: The total should 31.28 Btu without rounding SUM: 1361.28 Btu Total heat Removed in Btu (to one decimal place) = 1361.3 Btu The value of 31.3 Btu in Figure 3 could be updated to 31.28 Btu Figure 3's total Below the BTU scale reads 1364 Btu, It should be 1361.3 Btu
Status: Implemented

Date: 3/10/2022 1:31:57 PM
Module: 140102b
Version: 22
Page: 26
Comment: In the 4th paragraph, line 3, 10°F(12.2°C) should read 10 F° (5.5C°). °C vs. C° is the difference between an actual temperature vs. a temperature difference.
Status: Implemented

Date: 6/2/2022 11:30:29 AM
Module: 140102c
Version: 24
Page: 36
Comment: Figure 14 - Can the "Critial Point" at the peak also be labelled? Can two labels be applied to the left side and right side of the "Saturation Curve" To the left it can be labelled "Saturated Liquid Curve" and on the right side it can be labelled "Saturated Vapour Curve" Thank you
Status: Implemented

Date: 3/10/2022 1:36:22 PM
Module: 140102c
Version: 22
Page: 2
Comment: Update "atmospheric pressure" value in the definition from 101.325kPa to 101.3kPa to align with the values updated in 140102a
Status: Implemented

Date: 3/10/2022 1:51:55 PM
Module: 140102c
Version: 22
Page:
Comment: The paragraphs about Celsius to Kelvin conversion and Fahrenheit to Rankine conversion; at the end of each paragraph, each statements says that two decimal accuracy isn't normally required. So you can just replace 273.15 with 273 as well as replace 459.67 with 460. Contrary to this statement, on page 14, 15, 16 and 17 the arithmetic is using 459.6. I propose to have the arithmetic changed to reflect using 460 as absolute temperature. Problems 2, 3 and 4 on page follow my proposal.
Status: Implemented

Date: 3/10/2022 1:56:15 PM
Module: 140102c
Version: 22
Page: 29
Comment: The formula for Volume Flow Rate is incorrect. It should be "Specific volume of vapour pumped multiplied by mass flow rate."
Status: Implemented

Date: 12/5/2022 1:38:38 PM
Module: 140102c
Version: 22
Page:
Comment: page 3 states that Charles first law pressure is constant, page 14, 25, 27 state volume is constant, page 54 question 5 states volume is constant, 140102a page 3 states that in Charles first law pressure is constant
Status: Implemented

Date: 12/5/2022 1:45:14 PM
Module: 140102c
Version: 22
Page: 50
Comment: The Red line going on the angle (following the lines of entropy) starting from h4 has shifted over to the right and is not correctly drawn anymore as it was on page 49, it is now over at the 60F mark instead of 40F
Status: Implemented

Date: 11/30/2023 12:42:44 PM
Module: 140102c
Version: 25
Page: 30
Comment: In the "Volume flow rate (V)" section, can the formula be updated to V= Specific volume of vapour pumped x mass flow rate
Status: Approved for Review

Date: 11/30/2023 12:33:25 PM
Module: 140102c
Version: 25
Page: 22
Comment: The note at the bottom of the page says that "Refrigeration is measured by its inner diameter. A 1/2" tubes inner diameter is actually 1/2"" This should read "Refrigeration pipe and tubing is measured by its outer diameter. A 1/2" tubes outer diameter is actually 1/2" "
Status: Approved for Review

Date: 3/10/2022 2:08:42 PM
Module: 140102d
Version: 22
Page: 43
Comment: In the example at the bottom of the page; can we update the value of the "velocity" from 1000 fpm to 900.9 fpm to align with the values of the average duct velocity that was found using the table on page 42? 900 fpm x 1.76 square feet = 1585.6 cubic feet per minute
Status: Implemented

Date: 3/10/2022 2:19:15 PM
Module: 140102d
Version: 22
Page: 42
Comment: Step 3, 4 and 5 don't have the values for Pv substituted into the second part of the equation.
Status: Implemented

Date: 3/10/2022 2:21:27 PM
Module: 140102d
Version: 22
Page: 42
Comment: Can the value for Pi be updated to just use 3.14?
Status: Update in Progress

Date: 3/10/2022 2:26:48 PM
Module: 140102d
Version: 22
Page: 44
Comment: Change the value in the example question from 400 cfm to align with the value in the math found below the text. It should be 4.5 x 1767.2 cfm x 10 btu/ft3 = 79524 btu/min
Status: Implemented

Date: 12/5/2022 1:04:48 PM
Module: 140102d
Version: 21
Page: 21
Comment: The picture shows pressures at sea level and high altitude, they are the same pictures and pressures didn't change
Status: Implemented

Date: 12/5/2022 1:09:06 PM
Module: 140102d
Version: 21
Page: 49
Comment: Question 20 answers should be in BTU/Hour not BTU/min according to the middle of pg 44. Also page 44 does an answer in BTU/min as well right after stating it should be in BTU/hour
Status: Implemented

Date: 11/30/2023 1:05:07 PM
Module: 140102d
Version: 25
Page: 46
Comment: In the "Total Heat Transfer" Area - Can the units for Standard air Density be updated to 0.075 lb/ft³ instead of lb.ft - Under the 𝛥h, can the (Btuh) be updated to (Btu/h) as well as twice in the next longer sentence "The result is the total heat transfer, Qt, in Btu/h" It might help to add the cancelling of units lb/ft³ x min/hr x ft³/min x Btu/lb . After cancelling units you are left with Btu/hr
Status: Approved for Review

Date: 11/30/2023 12:52:53 PM
Module: 140102d
Version: 25
Page: 51
Comment: Question #20 is asking "How much heat is removed from air crossing a cooling coil if the air volume flow rate is 212 cfm and the amount of heat removed is 14 Btu for every cubic foot of air? Should read "How much heat is removed from air crossing a cooling coil if the air volume flow rate is 212 cfm and the amount of heat removed is 14 Btu for every pound of air?
Status: Approved for Review

Date: 11/29/2023 2:53:58 PM
Module: 140102d
Version: 24
Page: 44
Comment: Under "Total Heat Transfer; Qt is the total heat transferred, please add in "in Btu/hr" Where Delta-h is being defined as "is the amount of head added or removed in British thermal units per hour (Btuh)" should actually read "British thermal units per pound (Btu/lb). In the example at the bottom of the page, the text should be "Find the amount of heat removed from air crossing a cooling coil if the air volume flow rate is 400 cfm and the amount of heat removed is 10 Btu/lb of air" The units in the math in the example must also change to reflect the 10 Btu/lb Qt=4.5 x cfm x Delta h = 4.5 x 400 x 10 = 18,000 Btu/h
Status: Approved for Review

Date: 5/10/2022 12:35:53 PM
Module: 140102e
Version: 22
Page: 24
Comment: The first word in the second paragraph is "Always". This actually should be changed to "Never" as it relates to belts running on the bottom of a belt instead of the side walls of the belt.
Status: Implemented

Date: 12/5/2022 12:56:19 PM
Module: 140102e
Version: 22
Page: 15
Comment: Under Forward Curved Fan the 1st paragraph incorrectly states they are "non-overloading" and in the second paragraph it explains why they are "overloading" fans
Status: Implemented

Date: 4/14/2022 1:28:11 PM
Module: 140102i
Version: 21
Page: 20
Comment: Figure 6 should be updated to fall in line with the current B52.2018 code book. This new graphic can be found on page 25 of the new B52.2018 code book found on the CSA website library.
Status: Implemented

Date: 11/29/2023 1:12:42 PM
Module: 140102j
Version: 24
Page: 39
Comment: The answer to question number 23 says "2 psig (Table 5.1) Can this be updated to "2 psig (Table 5.1 of the CAN/CSA - B149.1)"?
Status: Approved for Review

Date: 9/13/2022 11:54:47 AM
Module: 140102k
Version: 24
Page: 15
Comment: Below "Btu Calculations" The value for "Steam specific heat" should be 0.46 not 0.50. thank you!
Status: Implemented

Date: 8/29/2022 1:17:05 PM
Module: 140103a
Version: 24
Page: 3
Comment: Below the "DANGER" table: The texts reads :"To Calculate the current flow through the body, divide the body resistance by the voltage applied to the body" . This text would imply that current is found by dividing resistance by voltage but this is incorrect. Current=Voltage/Resistance. So the text could read "To calculate the current flow through the body, using ohm's law, divide the voltage applied to the body divided by the resistance of the body."
Status: Implemented

Date: 10/5/2022 12:46:30 PM
Module: 140103a
Version: 24
Page: 29
Comment: In the text below "megohmmeters", in the last sentence it says " One standard for machinery safety states that, for test voltages at 500VDC, the minimum insulation resistance is 1Mohm" While the text does not list the standard to which this point is referring to, 1Mohm of insulation resistance is very low for trade practices. Around 4 Mohm is the minimum you would want to have, with complete confidence, that the motor would not intermittently short to ground on 600VAC supply.
Status: Implemented

Date: 10/27/2023 8:48:08 AM
Module: 140103b
Version: 24
Page: 19, 20
Comment: Question 15 states: “What is the current flowing through a 600 (ohm) resistance if the circuit operates on 120 volts ac? a) 0.0002 A b) 0.0080 A c) 0.0200 A d) 2.0000 A The answer key shows the answer as c, and if I=V(divided by) R 120 divided by 600 is 0.2 which is neither the answer in answer key, nor a possible answer listed in question 15.
Status: Approved for Review

Date: 6/7/2024 8:59:52 AM
Module: 140103g
Version: 24
Page: 1
Comment: In the introduction on page 1; It says that the module covers phasor diagrams but it does not.
Status: Approved for Review

Date: 3/3/2023 11:39:26 AM
Module: 140104a
Version: 24
Page: 42
Comment: In figure 30, the last items in the table are two pressure switch symbols. Can the name of each of those be changed to "close on rise of pressure " and the bottom one be changed to "open on rise of pressure "? Pressure switches cant be normally open or closed, instead how we use them to control pressure or other parts of a circuit.
Status: Approved for Review

Date: 11/3/2022 8:21:46 AM
Module: 140104a
Version: 24
Page: 5
Comment: The first Term at the top of the page should probably be damper, instead of amper.
Status: Implemented

Date: 3/14/2024 7:56:24 AM
Module: 140104a-bA
Version: 25
Page: 21
Comment: In the definitions, under "controlled variable" , it should say in the third line "Examples of variables are temperature, pressure, flow rate and humidity"
Status: Approved for Review

Date: 4/30/2024 1:43:06 PM
Module: 140104a-bA
Version: 25
Page: 27
Comment: Figure 28 - Internal wiring of Oil Failure Control is incorrect. Diagram needs to be re-done.
Status: Approved for Review

Date: 10/8/2024 9:07:18 AM
Module: 140104a-bA
Version: 25
Page: 14
Comment: In the third sentence under "Proportional or Modulating Control Mode" "For example, if a direct-acting controller that has a throttling range of 50 °F (10 °C) between 68 °F (20 °C) and 86 °F (30 °C)" should be "For example, if a direct-acting controller that has a throttling range of 18 F° (10 C°) between 68 °F (20 °C) and 86 °F (30 °C)"
Status: Approved for Review

Date: 12/2/2022 8:37:59 AM
Module: 140104c
Version: 24
Page:
Comment: On page 14, second paragraph, third line; Replace the word "call" with "need". On page 23, point #5, getting rid of the word "call" with "If the temperature controller decides that there is no need for cooling, the compressor and condenser fan do not run."
Status: Implemented

Date: 3/27/2024 9:45:57 AM
Module: 140104c
Version: 25
Page: 16
Comment: The time delay switch symbols and text in figure 17 are difficult to understand. Recommend using the time delay symbols and descriptions found in figure 16 , page 35 of 140104a-bA.
Status: Approved for Review

Date: 4/30/2024 2:47:55 PM
Module: 140104c
Version: 25
Page: 39 & 43
Comment: Figure 30 and figure 31 are incorrectly drawn. System will not function as drawn. TR3 prevents control circuit from being energized and terminal 4 is de-energized in defrost cycle so compressor will not pump-out. Should be redrawn using combination Defrost termination/ Fan delay switch TR3 is not required. Also Defrost termination/ Fan delay switch should be added to this module with a picture, probably in Objective Four.
Status: Approved for Review

Date: 12/3/2024 8:45:12 AM
Module: 140104c
Version: 25
Page: 3
Comment: In the second paragraph, there is some incorrect temperature conversion. The second sentence reads "...the evaporator must maintain a temperature of 15°F to 20°F (6.7°C to 9.4°C). Since the cut in is 37°F (2.8°C) and the cut out is as low as 15°F (9.4°C), the differential is 17 F° to 22F° (5.6°C to 8.3°C). It should be "...the evaporator must maintain a temperature of 15°F to 20°F (-9.4°C to -6.6°C). Since the cut in is 37°F (2.8°C) and the cut out is as low as 15°F (-9.4°C), the differential is 17 F° to 22F° (9.4 C° to 12.2 C°).
Status: Approved for Review

Date: 12/5/2022 1:01:03 PM
Module: 140104d
Version: 22
Page: 8
Comment: states there are 7000 grains of moisture in 1lb of dry air. it is 7000 grains of moisture in 1lb of water
Status: Implemented

Date: 4/30/2024 2:05:39 PM
Module: 140104d
Version: 25
Page: 42
Comment: why is there reference to VRF systems in this module? Should be removed as it does not align with module Rational or Objectives.
Status: Approved for Review

Date: 10/22/2024 9:36:54 AM
Module: 140104e
Version: 24
Page: 25
Comment: Figure 20 of the stepper motor diagram isn't a diagram of the more common two-pole stepper motor, this is more of a three phase motor. A simple graphic of a bipolar stepper motor and removing table one would be more useful information.
Status: Approved for Review


Archived Comments

Year: 2021

12/13/2021 5:42:46 PM
Module: 140102c
Version: 21
Page: 52
Comment: Calculation #6 on page 52 HoC = 60 - 40 = 20 This is a typo...should be 160, not 60... Thanks
Status: Implemented

11/1/2021 11:06:47 AM
Module: 140102a
Version: 21
Page:
Comment: When using the formulas from the ILM they use different values for the same formula . An example would be in one formula they use 101.35 and then another they use 101.325. This throws off the answers . The number I am told to use from the instructor is 101.3 moving forward . I hope this gets corrected as it was a not a nice feeling when I got my mark back after 3 hours of work .
Status: Implemented

10/6/2021 3:32:13 PM
Module: 140101c
Version:
Page: 39
Comment: Question 10 states, "Ventilation system requirments for the worksite are found in the: Both a and b would be correct to find ventilation system requirements. This question or the answers should be changed.
Status: Implemented

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