2025/2026 Manual D Test, Mechanical Law Exam, Mechanical A/C Service Exam,
Heating, Michigan Mechanical Code
The basic objective of Manual D is to design a duct system that will work with the ____ that is supplied with the HVAC equipment Blower
The airflow resistance produced by the duct system (duct runs, duct fittings and air-side
components) in terms of static pressure drop, shall_____ the external static pressure (ESP) Match produced
by the blower package when the blower delivers the desired CFM.
A _______ is the pressure loss that occurs between any two points of the duct system, whereas
_______ is the pressure loss that occurs between two points in the duct system that are Pressure Drop/Friction Rate
separated by a specific distance.
Pressure drop is measured in inches of water column (iwc) and friction rates are measured in inches of water column per _______ feet of
duct. 100
Using the formula to convert the system pressure drop value to a friction rate value found in
Section 1-6 calculates the friction rate for a forced air furnace with a blower capacity of 1400 0.10 iwc/100
cfm and a pressure drop of 0.18 with a total effective length (TEL) of 180 feet of duct.
(chart A-1 page 132) With the friction rate known for the above duct system using the friction
16
rate charts in appendix2, _____ round galvanized duct would be required.
The total pressure drop for a duct run equals the pressure loss for all____ sections plus the
Straight/Fitting
pressure loss produced by each and every ____ in the duct run.
Total Effective Legnth (TEL) is obtained by ____ the straight run and the fitting equilavent
Adding
length.
When adding a ducted return air to the system, some pressure is used to move air through
the return air duct, so less pressure is available for the supply side of the system. The only Total Effective
Length (TEL) change in the formula to convert the system pressure drop value to a friction rate value will be the
______.
Using the information in question 5, calculate the friction rate for a forced air furnace with a
blower capacity of 1400 cfm and a pressure drop of 0.18 with a total effective length (TEL) of 0.006
280 feet of duct allowing for the addition 100 feet of return air duct.
With the friction rate known for the above duct system, using the friction rate chart in appendix 2, ___round galvanized duct would be
required 18"
The procedure for sizing a duct system with multiple supply and return air outlets creating multiple effective lengths is to size based on the
_____ effective length value. Largest
Resistance created when air is forced through equipment, or a device installed in the air stream translates to a _____ across the component.
Pressure Drop
, 2015 Manual D Test, Mechanical Law Exam, Mechanical A/C Service Exam, Heating
Michigan Mechanical Code
.
Available static pressure is the pressure that is available for the straight duct runs and fittings after it is subtracted from the external static
pressure valve from the OEM Blower Table
Duct sizing is not based on the amount of pressure that the blower produces but on the net
pressure that is_______ to move the air through the circulation path that produces the most Available resistant
to airflow.
When considering air velocity for noise control, the maximum velocity for the supply side trunk
900, 700 is _______ fpm and ______ fpm for the return air trunk using rigid duct.
Friction rate duct sizing is not the only criteria to design a duct system. Velocity noise also
needs to be considered. IN most cases duct sizing that satisfies the friction rate procedure are too small to
satisfy the velocity limit therefore two sizes are created. The final design always larger uses
the________ of these two sizes.
Excessive path (oversized ducts) CFM problems are resolved by _________ in appropriate locations. Installing and adjusting balancing
dampers
The airflow rate that is required for a conditioned space depends on either the sensible
cooling load or heating load and on the temperature difference (TD) between the supply air Room Air and
the _______.
Using the psychrometric airflow calculation of section 1-13, _____ cfm would be required if
the manual J cooling load was 24,000 btu's with a supply air temperature of 57 degrees F and 1283 return air
temperature of 74 degrees F with an altitude correction factor of 1.
Using the psychrometric airflow calculation of section 1-13, _____ cfm would be required if
the manual J cooling load was 62,000 btu's with a supply air temperature of 127 degrees F 824 and
return air temperature of 70 degrees F with an altitude correction factor of 1.2
Once the design value for the blower cfm is known, the air flow required for each room can
be estimates by ______ the blower cfm by the room load and then ______ the by the Manual Multiplying / Dividing
J design load.
_______ cfm is required for room with a 4000 btu room load, a 1,000 -blower cfm and a 133 heating
load of 30,000 btu's.
To achieve the heating and cooling factors, the design loads are divided into the Blower CFM
The cooling factor of ______ would be required for a room with a cooling load of 4000 btu's
0.050
and a required 200 cfm airflow.
With a known cooling factor or 0.050 and a room sensible load of 6,000 btu's, an estimat-
300
ed______ cfm is known.
When speed increases on a blower what direction does the line move on the duct curve? up and to the right
Normally the blower is a factory installed component, however, one part of Manual D is used
to see if blower performance is _____ the airflow and pressure requirement of the proposed roughly compatible with
air distribution system.
, 2015 Manual D Test, Mechanical Law Exam, Mechanical A/C Service Exam, Heating
Michigan Mechanical Code
When air flows through straight duct, friction causes the static pressure in the duct to decrease
in the direction of flow. Using the formula in section 4-1, a pressure drop of _____ would be 0.25 the
result of a friction rate of 0.10 and a total duct length of 250 feet.
Panned joints and stud spaces are ______ by ACCA. not endorsed
The pressure drop produce by supply air grilles, registers and diffusers, return air grilles, and
manual balancing dampers is small. Manual D default value for any of these items is ______ 0.03
.
An engineered low resistance path shall be provided for every room or space that receives supply air. This can be established by using
_______. dedicated return air duct/ transfer duct/ opening filled with two return air grilles.
Air volume is controlled by ______. Dampers
A system has an external static pressure if 0.49 IWC, an auxiliary heating coil of 0.14 IWC, one
register of 0.03 IWC, one return of 0.0c IWC and one open balancing damper of 0.03. The 0.26 available
static pressure remaining is _______ IWC.
A 1400 cfm duct system with an external static pressure of 0.42 w.c with a dry coil of 0.11 w.c and an electronic air filter of o.08 w.c has _____
total available static pressure remaining? 0.23 w.c
Per figure 6-5 on page 38, the fan amp draw will _____ if the friction rate is 0.18 and below the plotted point 0.07 at 0.20 iwc shown on the
chart. Decrease
What size round galvanized duct would be required for a system with 800 cfm at a .4 iwc 10"
What size would rigid round fiberglass duct need to be for a system with 1200 cfm at .01 iwc? 22"
Based on equal friction a 52 x 20 rectangular duct is equivalent to a ____ round duct. 34.3
With an available height of 12' what would be the width have to be to equal a 19' round pipe? 26
With a reference velocity of 900 fpm and 0.08 iwc, a transitional take off for rectangular duct
(1-D) has an effective length (EL) of ____ where a rectangular duct attached directly from the plenum (1 -C)
has an EL of ______.
With a referenced velocity of 900 fpm and 0.08 iwc, a bullhead with no vanes (10) at H/W of 0.50 has an EL of ______ where a bullhead tee
(1P) with turning vanes has an EL of ______.
With a reference velocity of 900 fpm and a friction rate of 0.08, what is the effective length of a 2J fitting with 3 downstream branches to the
end of the trunk reducer r end of trunk duct? 70
With a referenced velocity of 700 fpm and a 0.08 iwc, what is the maximum achievable cfm from a stud wall cavity. 200
What would the EL be for a 45- degree elbow at 600fpm for flexible duct junction box with a 5
R/D of 1.0?
Heating, Michigan Mechanical Code
The basic objective of Manual D is to design a duct system that will work with the ____ that is supplied with the HVAC equipment Blower
The airflow resistance produced by the duct system (duct runs, duct fittings and air-side
components) in terms of static pressure drop, shall_____ the external static pressure (ESP) Match produced
by the blower package when the blower delivers the desired CFM.
A _______ is the pressure loss that occurs between any two points of the duct system, whereas
_______ is the pressure loss that occurs between two points in the duct system that are Pressure Drop/Friction Rate
separated by a specific distance.
Pressure drop is measured in inches of water column (iwc) and friction rates are measured in inches of water column per _______ feet of
duct. 100
Using the formula to convert the system pressure drop value to a friction rate value found in
Section 1-6 calculates the friction rate for a forced air furnace with a blower capacity of 1400 0.10 iwc/100
cfm and a pressure drop of 0.18 with a total effective length (TEL) of 180 feet of duct.
(chart A-1 page 132) With the friction rate known for the above duct system using the friction
16
rate charts in appendix2, _____ round galvanized duct would be required.
The total pressure drop for a duct run equals the pressure loss for all____ sections plus the
Straight/Fitting
pressure loss produced by each and every ____ in the duct run.
Total Effective Legnth (TEL) is obtained by ____ the straight run and the fitting equilavent
Adding
length.
When adding a ducted return air to the system, some pressure is used to move air through
the return air duct, so less pressure is available for the supply side of the system. The only Total Effective
Length (TEL) change in the formula to convert the system pressure drop value to a friction rate value will be the
______.
Using the information in question 5, calculate the friction rate for a forced air furnace with a
blower capacity of 1400 cfm and a pressure drop of 0.18 with a total effective length (TEL) of 0.006
280 feet of duct allowing for the addition 100 feet of return air duct.
With the friction rate known for the above duct system, using the friction rate chart in appendix 2, ___round galvanized duct would be
required 18"
The procedure for sizing a duct system with multiple supply and return air outlets creating multiple effective lengths is to size based on the
_____ effective length value. Largest
Resistance created when air is forced through equipment, or a device installed in the air stream translates to a _____ across the component.
Pressure Drop
, 2015 Manual D Test, Mechanical Law Exam, Mechanical A/C Service Exam, Heating
Michigan Mechanical Code
.
Available static pressure is the pressure that is available for the straight duct runs and fittings after it is subtracted from the external static
pressure valve from the OEM Blower Table
Duct sizing is not based on the amount of pressure that the blower produces but on the net
pressure that is_______ to move the air through the circulation path that produces the most Available resistant
to airflow.
When considering air velocity for noise control, the maximum velocity for the supply side trunk
900, 700 is _______ fpm and ______ fpm for the return air trunk using rigid duct.
Friction rate duct sizing is not the only criteria to design a duct system. Velocity noise also
needs to be considered. IN most cases duct sizing that satisfies the friction rate procedure are too small to
satisfy the velocity limit therefore two sizes are created. The final design always larger uses
the________ of these two sizes.
Excessive path (oversized ducts) CFM problems are resolved by _________ in appropriate locations. Installing and adjusting balancing
dampers
The airflow rate that is required for a conditioned space depends on either the sensible
cooling load or heating load and on the temperature difference (TD) between the supply air Room Air and
the _______.
Using the psychrometric airflow calculation of section 1-13, _____ cfm would be required if
the manual J cooling load was 24,000 btu's with a supply air temperature of 57 degrees F and 1283 return air
temperature of 74 degrees F with an altitude correction factor of 1.
Using the psychrometric airflow calculation of section 1-13, _____ cfm would be required if
the manual J cooling load was 62,000 btu's with a supply air temperature of 127 degrees F 824 and
return air temperature of 70 degrees F with an altitude correction factor of 1.2
Once the design value for the blower cfm is known, the air flow required for each room can
be estimates by ______ the blower cfm by the room load and then ______ the by the Manual Multiplying / Dividing
J design load.
_______ cfm is required for room with a 4000 btu room load, a 1,000 -blower cfm and a 133 heating
load of 30,000 btu's.
To achieve the heating and cooling factors, the design loads are divided into the Blower CFM
The cooling factor of ______ would be required for a room with a cooling load of 4000 btu's
0.050
and a required 200 cfm airflow.
With a known cooling factor or 0.050 and a room sensible load of 6,000 btu's, an estimat-
300
ed______ cfm is known.
When speed increases on a blower what direction does the line move on the duct curve? up and to the right
Normally the blower is a factory installed component, however, one part of Manual D is used
to see if blower performance is _____ the airflow and pressure requirement of the proposed roughly compatible with
air distribution system.
, 2015 Manual D Test, Mechanical Law Exam, Mechanical A/C Service Exam, Heating
Michigan Mechanical Code
When air flows through straight duct, friction causes the static pressure in the duct to decrease
in the direction of flow. Using the formula in section 4-1, a pressure drop of _____ would be 0.25 the
result of a friction rate of 0.10 and a total duct length of 250 feet.
Panned joints and stud spaces are ______ by ACCA. not endorsed
The pressure drop produce by supply air grilles, registers and diffusers, return air grilles, and
manual balancing dampers is small. Manual D default value for any of these items is ______ 0.03
.
An engineered low resistance path shall be provided for every room or space that receives supply air. This can be established by using
_______. dedicated return air duct/ transfer duct/ opening filled with two return air grilles.
Air volume is controlled by ______. Dampers
A system has an external static pressure if 0.49 IWC, an auxiliary heating coil of 0.14 IWC, one
register of 0.03 IWC, one return of 0.0c IWC and one open balancing damper of 0.03. The 0.26 available
static pressure remaining is _______ IWC.
A 1400 cfm duct system with an external static pressure of 0.42 w.c with a dry coil of 0.11 w.c and an electronic air filter of o.08 w.c has _____
total available static pressure remaining? 0.23 w.c
Per figure 6-5 on page 38, the fan amp draw will _____ if the friction rate is 0.18 and below the plotted point 0.07 at 0.20 iwc shown on the
chart. Decrease
What size round galvanized duct would be required for a system with 800 cfm at a .4 iwc 10"
What size would rigid round fiberglass duct need to be for a system with 1200 cfm at .01 iwc? 22"
Based on equal friction a 52 x 20 rectangular duct is equivalent to a ____ round duct. 34.3
With an available height of 12' what would be the width have to be to equal a 19' round pipe? 26
With a reference velocity of 900 fpm and 0.08 iwc, a transitional take off for rectangular duct
(1-D) has an effective length (EL) of ____ where a rectangular duct attached directly from the plenum (1 -C)
has an EL of ______.
With a referenced velocity of 900 fpm and 0.08 iwc, a bullhead with no vanes (10) at H/W of 0.50 has an EL of ______ where a bullhead tee
(1P) with turning vanes has an EL of ______.
With a reference velocity of 900 fpm and a friction rate of 0.08, what is the effective length of a 2J fitting with 3 downstream branches to the
end of the trunk reducer r end of trunk duct? 70
With a referenced velocity of 700 fpm and a 0.08 iwc, what is the maximum achievable cfm from a stud wall cavity. 200
What would the EL be for a 45- degree elbow at 600fpm for flexible duct junction box with a 5
R/D of 1.0?
