1. Maria’s Restaurant Lesson 22 Appendix C Zone 2 Duct Design

2. Maria’s Restaurant Design
(Staff: Maria & 7 Employees each shift. Glass Store Front and front door) C1 R1 F1
Woman’s
Restroom
1 handicap
1 standard
Men’s
Restroom
1 handicap
1 urinal S3
Shelv.. R3 DW
Bar 12 X 10
Seating 12
Counter C6
Bar S2 B2
Ice R4
Shelving/Storage
25 ft.
Shelv. B1 C7 C2
Fry S1
Restaurant 33 X 15
11 X 4 & 11 X 6
Seating 58
CT/O C3 SP SK H1 R2 F2 WH S1
66 ft.
B = Beverage Area R = Refrigerator (blue walk in
C = Counter S = Sink; S1 Hand; S2 3 Pot; S3 Bar
CT = 4 burner plus flat top over ovens SK= Steam Kettle
DW = Dishwasher SP = Salad/cold Prep table
F = Freezer (blue walk in) H1 = Hot Prep Table with Heat Lamp Shelf

3. Zone 2 Kitchen Exhaust & OA Sketch
AIR In
1,150 CFM
AIR In
600 CFM
Zone 1: Restaurant Area Fresh
Air Required
589 CFM
EX. AIR
AIR In
Setting 1: 1,900 CFM
Setting 2: 100 CFM
AIR In
500 CFM
Package Heat Pump
ERV
2 Bathrooms
Airflow ½ each
EX. AIR
EX 2
Zone 1 EX AIR OUT
500 CFM
Supply Air
3,200 CFM
Return Air
Setting 1: 1,300 CFM
Setting 2: 3,100 CFM
EX 1
EX 2 AIR Out
600 CFM
EX AIR Out
Speed/Setting 1: 3,450 CFM
Speed/Setting 2: 1,650 CFM

4. Maria’s Restaurant Duct Design
(one grid square = one ft2)
Zone 2 G
Supply Diffuser 550 CFM H F H A
6 Supply Diffusers 400 CFM B
25 ft.
Zone 1A
Duct F D
Zone 1 B
EX. Hood E G E C A C D
5 Supply Diffusers 530 CFM
66 ft.
Zone 1 Constant Volume 2,400 CFM
Return: 1,711 CFM
Zone 2 Constant Volume 3,200 CFM
Stage 1 Return: 1,300 CFM
Stage 2 Return: 3,100 CFM

5. Fan Cabinet Return Connections for 7
Fan Cabinet Return Connections for 7.5 & 10 Ton Rooftop Package Unit Supply Duct
27”× 24” = OEM Opening
24”
27”
26” Round
24”
27”
Friction Rate (FR) Calculation
Zone 1 Unit Return Trunk: 2,400 CFM ÷ 4.5 ft2 = 534 FPM
FR = (Will use as per Manual Q Minimum value)
Zone 2 Unit Return Trunk: 3,200 CFM ÷ 4.5 ft2 = 711 FPM
FR = 0.030
Note: Sketch not to scale

6. Zone 2 Friction Rate Not a significant Pressure Drop:
For longer runs or smaller ducting
the return total needs to be added
to the supply to obtain the system’s
total loss.
Friction Rate 0.030

7. Not a significant Pressure Drop: For longer runs or smaller ducting
Fan Cabinet Supply Connections for 7.5 & 10 Ton Rooftop Package Unit Supply Duct
28”× 20” = OEM Opening
20”
28”
26” Round
Not a significant Pressure Drop:
For longer runs or smaller ducting
the return total needs to be added
to the supply to obtain the system’s
total loss.
20”
28”
Friction Rate (FR) Calculation
Zone 1 Unit Return Trunk: 2,400 CFM ÷ 3.89 ft2 = 617 FPM
FR = 0.026
Zone 2 Unit Return Trunk: 3,200 CFM ÷ 3.89 ft2 = 823 FPM
FR = 0.045
Note: Sketch not to scale

8. Zone 2 Kitchen Duct Design A to B
10’ 4’ 3’ 3’ 3’ 4’ 2’
Diffuser
90O Rectangular Elbow
Wye 90
Return Register

9. Friction Rate 0.2
Galvanized Metal
Corresponding
Airflows in CFM
Friction Rate 0.2
Duct Board

10. A to B

11. Typical Straight Duct Calculation
CE = f/100 × ft. ÷ 100
CE = × 4 ÷ 100 =

12. Typical Wye Calculation

13. Zone 2 Kitchen Duct Design A to B
10’ 4’ 3’ 3’ 3’ 4’ 2’
Diffuser
90O Rectangular Elbow
Wye 90
Return Register

14. Zone 2 Wye C Rectangular (Pv)
Using the Manual Q Table A6-5
to Calculate for main Coefficient
C at point C on the duct drawing:
Ab ÷ Ac = 154 ÷ 560 = 0.275
Ab ÷ As = 154 ÷ 408 = 0.377
Qb ÷ Qc = 530 ÷ 3,200 = 0.166
Where:
Ab = 7 × 22 = 154 in2
Ac = 28 × 20 = 560 in2
As = 28 × 17 = 408 in2

15. Main Branch Wye D Rectangular (Pv)
Ab/As
Ab/Ac
Wye Main Branch Coefficient C
Qb/Qc
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.25
-0.01
-0.03
0.05
0.13
0.21
0.29
0.38
0.46
0.33
0.08
-0.02
0.02
0.16
0.24
0.34
-0.06
-0.05
0.06
0.12
0.19
0.27
0.35
0.67
0.04
-.02
-0.04
0.23
0.37
1.0
0.72
0.48
0.28
0.09
0.18
0.30
0.22
1.33
0.10
0.01
0.03
0.20
2.0
0.62
Close Enough to 0
Ab ÷ Ac = 154 ÷ 560 = 0.275
Ab ÷ As = 154 ÷ 408 = 0.377
Qb ÷ Qc = 530 ÷ 3,200 = 0.166

16. WYE 90O
Pt = C × Pv
Pt = 0 × = 0

17. Zone 2 Smooth Radius 3 Vane 90
H/W = 7 ÷ 22 = 0.31
R/W = 11 ÷ 22 = 0.5
No need to interpolate C = 0.01
R/W
Coefficient C
H/W
0.25
0.5
1.0
1.5
2.0
3.0
4.0
5.0
6.0
7.0
8.0
0.05
0.11
0.10
0.12
0.13
0.14
0.16
0.18
0.19
0.21
0.22
0.23
0.07
0.06
0.08
0.09
0.15
0.04
0.20
0.03
0.02
0.30
0.01
0.35
0.40
0.45
0.50
0.31

18. Rounded up to 0.0001 to fit sheet Pt = C × Pv
Smooth Radius 3 Vane 90 Calculations
Pt = × 0.01 =
Rounded up to to fit sheet
Pt = C × Pv

19. Zone 2 Total Loss = 0.503

20. 10’ 22×7
3’ 22×15
3’ 28×17
4’ 28×20
4’ 22×7
3’ 22×11
2’ 28×15

21. Zone 2 Kitchen Duct Design A to B
10’ 4’ 3’ 3’ 3’ 4’ 2’
Diffuser
90O Rectangular Elbow
Wye 90
Return Register

22. Zone 2 Kitchen Duct Design A to B
Diffuser
90O Rectangular Elbow
Wye 90
Return Register

24. 24”
27”
26” Round
24”
27”
Friction Rate (FR) Calculation
Zone 1 Unit Return Trunk: 2,400 CFM ÷ 4.5 ft2 = 534 FPM
FR = (Will use as per Manual Q Minimum value)
Zone 2 Unit Return Trunk: 3,200 CFM ÷ 4.5 ft2 = 711 FPM
FR = 0.030
Note: Sketch not to scale

25. Field Notes
To do field diagnostics technicians need a differential pressure meter and the ability to read and use a duct slide rule. For further training on the duct slide rule see the Qtech on line course Duct Design Basics. For further training see Technician’s Guide & Workbook for Quality Installations and/or the related Qtech course.