1. Lesson 23 Appendix C Exhaust Calculation

2. Maria’s Restaurant
Maria’s

3. Maria’s Restaurant Design
(Staff: Maria & 6 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.
Kitchen Area = 533 Sqft Bar Area = 180 Sqft
Woman Rest Room = 110 Sqft Men Rest Room = 99 Sqft
Bar Area = 180 Sqft Entry Area = 120 Sqft
Dinning Area = 605 Sqft

4. Kitchen Exhaust Requirements Typical Type 1 Exhaust Hood With Perforated Perimeter Supply (11.5 ft. linear length 3,450 CFM hood with 1,150 CFM untempered ASHRAE 62 Class 1 makeup air)

5. Hood Types
Double Island Canopy
Eyebrow

6. Hood Types
Wall Mounted Canopy
Pass Over

7. Hood Types
Single Island Canopy
Back Shelf

8. Hood Duty Definitions
Light Duty: Gas & Electric Ovens, steamers, and ranges. Food Warmers, pasta cookers, pizza ovens, Non- cooking appliance, smoker, rotisserie. Medium Duty: Combi-Ovens, Gas & Electric Fryers, Griddles, Tilting skillets, tilting braising pans grill, hibachi grill, salamander

9. Hood Duty Definitions
Heavy Duty: Upright broiler, electric Char-broiler Extra-Heavy Duty: Gas Char-broiler, Mesquite, infrared broiler, lava rock char-broiler, wok, chain broiler.

10. Hood Type Definitions
Type I hoods: Required over cooking equipment that produces grease laden effluent. Must have a sealed or welded exhaust duct system. Type II hoods: Used over cooking equipment that does not produce grease.

11. 2015 Uniform Mechanical Code (IMC) Airflow Requirement (air class 2)
Type 1 Exhaust Hood CFM
2015 Uniform Mechanical Code (IMC)
Airflow Requirement (air class 2)
Type of Hood
Airflow by Duty
(CFM per linear foot of hood)
Light
Medium
Heavy
Backshelf/Passover
250
300
400
Double Island Canopy
Eyebrow
Not Allowed
Single Island Canopy
500
600
Wall Mounted Canopy
200
11.5 ft hood X 300 CFM = 3,450 CFM

12. Type 2 Exhaust Hood CFM Type 2 used for dishwasher/humidity removal:
Not Less Than 200 CFM per linear foot of hood.
3 ft hood X 200 CFM = 600 CFM

13. Operational Outside Air Minimums
Outside air required for the kitchen side of the
building by ASHRAE 62.1 is 119 CFM: Thus, 119 CFM
must be brought in at all times.
4,050 CFM will be exhausted through the two
kitchen exhaust hoods. That will leave a negative
3,931 CFM of air if only 119 CFM is brought in from
the outside. Thus, an additional 3,931 CFM of air
will need to be brought into the kitchen if it is to
remain at a neutral pressure with respect to the
outside. (slightly positive to the outside is preferable)

14. Kitchen Exhaust Total
Cooking Hood: 3,450 CFM Dish washer Hood: 600 CFM Total: 4,050 CFM

15. Kitchen Exhaust & OA Sketch
AIR In
1,150 CFM
AIR In
600 CFM
AIR In
Setting 1: 1,900 CFM
Setting 2: 100 CFM
EX. AIR
#2 Package Heat Pump
ERV
EX AIR OUT
500 CFM
EX. AIR
AIR In
500 CFM
EX 2
Supply Air
3,200 CFM
Return Air
Setting 1: 1,300 CFM
Setting 2: 3,100 CFM
2 Bathrooms
Airflow ½ each
EX 1
EX 2 AIR
600 CFM
EX AIR
Speed/Setting 1: 3,450 CFM
Speed/Setting 2: 1,650 CFM
Kitchen Area
(+0.001” IWC)
Bar & Dining Area
(+0.004” IWC)

16. Kitchen Exhaust Total The Total CFM Requiring heating and cooling
is Lowered to: 4,050 – 2,050 = 2,000
Cooking Hood: 3,450 CFM Dish washer Hood: 600 CFM Total: 4,050 CFM Bring 1,150 CFM into the hood by a separate outside air fan. Bring 600 CFM to dish wash area when exhaust hood is on through designated outside air fan. Bring 500 CFM into kitchen area from Bathroom ERV constant volume.

17. Kitchen Exhaust & OA Sketch
AIR In
1,150 CFM
AIR In
600 CFM
AIR In
Setting 1: 1,900 CFM
Setting 2: 100 CFM
EX. AIR
#2 Package Heat Pump
ERV
EX AIR OUT
500 CFM
EX. AIR
AIR In
500 CFM
EX 2
Supply Air
3,200 CFM
Return Air
Setting 1: 1,300 CFM
Setting 2: 3,100 CFM
2 Bathrooms
Airflow ½ each
EX 1
EX 2 AIR
600 CFM
EX AIR
Speed/Setting 1: 3,450 CFM
Speed/Setting 2: 1,650 CFM
Kitchen Area
(+0.001” IWC)
Bar & Dining Area
(+0.004” IWC)

18. Kitchen Exhaust Requirements Typical Type 1 Exhaust Hood With Perforated Perimeter Supply (11.5 ft. linear length 3,450 CFM hood with 1,150 CFM untempered ASHRAE 62 Class 1 makeup air)

19. Further Savings: Two Speed Type I Exhaust Hood
The Type I hood selected is designed with an automated control that senses usage. When there is no usage, down and the hood fan lowers it’s speed so only 1,650 CFM are being exhausted by the hood when the cooking equipment is not being used. Thus, only 100 CFM is being conditioned by the Kitchen HVAC system.

20. Kitchen Exhaust & OA Sketch
AIR In
1,150 CFM
AIR In
600 CFM
AIR In
Setting 1: 1,900 CFM
Setting 2: 100 CFM
EX. AIR
#2 Package Heat Pump
ERV
EX AIR OUT
500 CFM
EX. AIR
AIR In
500 CFM
EX 2
Supply Air
3,200 CFM
Return Air
Setting 1: 1,300 CFM
Setting 2: 3,100 CFM
2 Bathrooms
Airflow ½ each
EX 1
EX 2 AIR
600 CFM
EX AIR
Speed/Setting 1: 3,450 CFM
Speed/Setting 2: 1,650 CFM
Kitchen Area
(+0.001” IWC)
Bar & Dining Area
(+0.004” IWC)

21. Dining & Bar Exhaust & OA Sketch
AIR In
500 CFM
AIR In 689 CFM
# 1 Package Heat Pump
ERV
EX AIR OUT
500 CFM
EX. AIR
Supply Air
2,400 CFM
2 Bathrooms
Airflow ½ each
Return Air
1,711 CFM
Kitchen Area
(+0.001” IWC)
Bar & Dining Area
(+0.004” IWC)

22. Dedicated Outdoor Air Unit

23. Field Notes
Technicians should be able to identify imbalances in exhaust and makeup air by simply verifying airflow directions. Technicians can use a piece of tissue or a smoke pencil to identify airflow paths and the relative building pressures they indicate. Most commercial buildings have an airflow related problem somewhere within their walls. Understanding how the systems work together is very important before making an adjustment to any of the components.