Kitchen Exhaust Systems
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
Showing changes from Rev 1
to Rev 2
in Kitchen Exhaust Systems.
---
title: Kitchen Exhaust Systems
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### General exhaust fans and fan selection for non-grease service are covered by [[sync/hvac-fans]]; only grease-rated exhaust fans are within this standard. {note}
−### Volume, fire, and combination fire/smoke dampers are covered by [[sync/louvers-and-dampers]]; Type I grease ducts are exempt from dampers and shall contain none, but dampers in connected makeup air and general systems remain under that standard. {note}
+### Volume, fire, and combination fire/smoke dampers are covered by [[sync/louvers-and-dampers]]; Type I grease ducts are exempt from dampers and shall contain none, but dampers in connected makeup air and general systems remain under that standard.
### Air balancing, capture-and-containment field verification, and commissioning of the completed system are covered by [[sync/testing-adjusting-and-balancing]]. {note}
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## Type I hoods shall be provided over all cooking equipment that produces grease-laden vapors, and Type II hoods shall be provided over equipment that produces only heat, moisture, or products of combustion without grease. {note}
−## Makeup air shall maintain the kitchen at a slight negative pressure, on the order of −0.05 in. w.g. relative to adjacent occupied spaces, so that cooking odors and heat do not migrate into the dining room while the kitchen does not depressurize enough to backdraft fuel-fired appliances. {note}
+## Makeup air shall maintain the kitchen at a slight negative pressure, on the order of −0.05 in. w.g. relative to adjacent occupied spaces, so that cooking odors and heat do not migrate into the dining room while the kitchen does not depressurize enough to backdraft fuel-fired appliances.
## In cold climates, makeup air shall be tempered so that untempered outdoor air does not chill staff at the cooking line or collapse the thermal plume the hood relies on for capture; energy-code limits on winter supply temperature shall be observed, with indirectly tempered makeup air permitted to be delivered as low as 60 °F under ASHRAE 90.1. {note}
+## The hood cooking duty classification shall be specified to match the cooking equipment served by the hood.
+
```datasheet
label: Hood Cooking Duty Classification
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```
+## The hood type shall be specified as Type I or Type II based on whether the cooking equipment produces grease-laden vapor.
+
```datasheet
label: Hood Type
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```
+## The climate zone makeup air tempering shall be specified so untempered outdoor air does not chill the cooking line or collapse the hood's thermal plume, subject to applicable energy-code supply-temperature limits.
+
```datasheet
label: Climate Zone Makeup Air Tempering
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### Type I hood interior surfaces shall be liquid-tight and continuously welded so that condensed grease drains to the integral grease trough and gutter rather than seeping into seams.
−### Each Type I hood shall be furnished with listed grease filters or baffle extractors, removable for cleaning, that drain captured grease to the hood's grease cup. {note}
+### Each Type I hood shall be furnished with listed grease filters or baffle extractors, removable for cleaning, that drain captured grease to the hood's grease cup.
−### Each Type I hood shall be furnished with a continuous grease gutter and a removable grease cup at the low point of the hood. {note}
+### Each Type I hood shall be furnished with a continuous grease gutter and a removable grease cup at the low point of the hood.
```datasheet
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### The hood shall be mounted so that the lower edge is no higher above the cooking surface than the listing and the duty permit, because raising the hood enlarges the capture area and increases the required exhaust rate.
−### The hood face shall maintain a capture velocity of at least 50 FPM for light-duty cooking and at least 75 FPM for heavy-duty and wok cooking per ASHRAE 154-2016. {note}
+### The hood face shall maintain a capture velocity of at least 50 FPM for light-duty cooking and at least 75 FPM for heavy-duty and wok cooking per ASHRAE 154-2016.
```datasheet
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### Where a short-circuit or front-face supply plenum is integral to the hood, it shall deliver makeup air at the hood face without disrupting the capture of grease-laden vapor into the exhaust collar.
−### Short-circuit makeup air introduced through an integral plenum shall be limited to the fraction the hood is listed to handle.
−
−### Short-circuit makeup air reduces the heating and cooling load on the makeup air unit by introducing a portion of replacement air directly at the hood; excessive short-circuit air beyond the listed fraction spills cooking effluent past the filters. {note}
−
```datasheet
label: Integral Supply Plenum
…6 unchanged lines
```
+### Short-circuit makeup air introduced through an integral plenum shall be limited to the fraction the hood is listed to handle.
+
+### Short-circuit makeup air reduces the heating and cooling load on the makeup air unit by introducing a portion of replacement air directly at the hood; excessive short-circuit air beyond the listed fraction spills cooking effluent past the filters. {note}
+
# Exhaust Airflow {toc}
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### Horizontal grease duct runs shall slope not less than 1/4 in. per foot (2%) toward the hood or toward an approved grease reservoir per IMC Section 506.3.2 and NFPA 96 §4.3.
−### A flat or reverse-sloped duct section pools condensed grease and creates a fire hazard, so the slope shall be verified in the structural and BIM coordination of every horizontal run. {note}
−
```datasheet
label: Horizontal Duct Slope Toward Hood / Reservoir
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```
+### A flat or reverse-sloped duct section pools condensed grease and creates a fire hazard, so the slope shall be verified in the structural and BIM coordination of every horizontal run. {note}
+
## Velocity {toc}
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### Grease duct shall maintain a clearance to combustible construction of not less than 18 in. per IMC Section 506.3.1 and NFPA 96 §4.2.1, reducible to 3 in. to noncombustible construction.
−### Where the 18 in. clearance cannot be maintained, the duct shall be enclosed in a fire-rated shaft or wrapped in an ASTM E2336 listed zero-clearance enclosure system installed per its listing.
−
−### Grease duct routed through occupied spaces without a rated shaft or a listed zero-clearance enclosure is a common permit-review rejection, so the enclosure strategy shall be resolved and shown on the drawings before submission. {note}
−
```datasheet
label: Duct Clearance / Enclosure Strategy
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```
+### Where the 18 in. clearance cannot be maintained, the duct shall be enclosed in a fire-rated shaft or wrapped in an ASTM E2336 listed zero-clearance enclosure system installed per its listing.
+
+### Grease duct routed through occupied spaces without a rated shaft or a listed zero-clearance enclosure is a common permit-review rejection, so the enclosure strategy shall be resolved and shown on the drawings before submission. {note}
+
### Type I grease ducts shall not contain fire dampers or smoke dampers; they are exempt under IBC Section 717.5.3 and NFPA 96 §4.5, and a damper installed in a grease duct traps grease and creates a fire hazard. {note}
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### Cleaning access panels shall be provided at each change of direction and along straight runs at not more than 12 ft on center on horizontal runs and not more than 20 ft on center on vertical runs per NFPA 96 §12.2.
+```datasheet
+label: Horizontal Access Panel Spacing
+type: range
+unit: ft
+min: 6
+max: 12
+step: 1
+default: 12
+```
+
### Access panels shall be not less than 20 in. × 20 in. where the duct dimension permits, sized so the full internal duct surface can be reached and cleaned.
−### Undersized or too-widely-spaced access panels prevent the duct from being cleaned to NFPA 96 §11 and are routinely rejected by fire marshals and health inspectors, so panel size and spacing shall be shown on the grease duct shop drawings. {note}
−
```datasheet
label: Access Panel Size
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```
−```datasheet
−label: Horizontal Access Panel Spacing
−type: range
−unit: ft
−min: 6
−max: 12
−step: 1
−default: 12
−```
+### Undersized or too-widely-spaced access panels prevent the duct from being cleaned to NFPA 96 §11 and are routinely rejected by fire marshals and health inspectors, so panel size and spacing shall be shown on the grease duct shop drawings. {note}
### The routing of the grease duct from each hood collar to the exhaust fan is shown on the drawings. [[drawing: grease duct routing plan]]
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### Upblast roof-mounted fans, inline grease-tight fans, and grease-rated utility sets are each acceptable for grease service when listed to UL 705 Supplement SC; the upblast roof fan is the default for typical restaurant applications. {note}
−### Inline fans, where used, shall be a grease-tight housing listed for the service and shall be provided with a residue collection and drainage provision at the housing low point. {note}
+### Inline fans, where used, shall be a grease-tight housing listed for the service and shall be provided with a residue collection and drainage provision at the housing low point.
```datasheet
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### A grease collection device shall be provided at the base of each duct riser or at the fan to receive drained grease, and the collector shall not exceed 1 gal capacity before an automatic shutoff or alarm per NFPA 96 §7.2.
−### The fan housing and curb shall be sealed grease-tight so that condensed grease drains back into the duct and collector rather than onto the roof membrane. {note}
+### The fan housing and curb shall be sealed grease-tight so that condensed grease drains back into the duct and collector rather than onto the roof membrane.
```datasheet
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### Makeup air quantity shall be specified at 80% to 90% of the exhaust volume so that the kitchen is held at a slight negative pressure relative to adjacent spaces, with a default of 85%.
−### Mechanical makeup air shall not draw flue gases from water heaters, furnaces, or other fuel-fired appliances in adjacent spaces; the makeup air quantity shall be coordinated with the building pressurization so the kitchen does not backdraft those appliances. {note}
+### Mechanical makeup air shall not draw flue gases from water heaters, furnaces, or other fuel-fired appliances in adjacent spaces; the makeup air quantity shall be coordinated with the building pressurization so the kitchen does not backdraft those appliances.
```datasheet
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## Delivery and Tempering {toc}
−### Makeup air shall be delivered by an integral hood supply plenum, by ceiling diffusers near the cooking line, or by a transfer-air path from conditioned adjacent space, sized so that delivery velocity does not disturb hood capture. {note}
+### Makeup air shall be delivered by an integral hood supply plenum, by ceiling diffusers near the cooking line, or by a transfer-air path from conditioned adjacent space, sized so that delivery velocity does not disturb hood capture.
### The makeup air heating source shall be selected as direct-fired gas, indirect-fired gas, or heat-pump/DX, coordinated with the available fuel supply and the energy code, and the gas heating section shall be sized for the design winter heating load rather than for cooling capacity alone. {note}
−### Makeup air unit gas heating capacity shall be confirmed against the available gas service, because a large makeup air unit serving a large exhaust in a cold climate can demand more gas than the building service was sized to deliver; coordinate the gas load with the plumbing scope. {note}
+### Makeup air unit gas heating capacity shall be confirmed against the available gas service, because a large makeup air unit serving a large exhaust in a cold climate can demand more gas than the building service was sized to deliver; coordinate the gas load with the plumbing scope.
```datasheet
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## DCKV shall be evaluated for every Type I hood under the adopted energy code; ASHRAE 90.1-2019 Section 6.5.7.1 requires DCKV for any single Type I hood with an exhaust rate of 5,000 CFM or greater, or where total kitchen exhaust is 15,000 CFM or greater. {note}
−## Where DCKV is required or elected, the system shall vary exhaust fan and makeup air fan speed through variable-frequency drives in response to optical and temperature sensors that detect cooking activity. {note}
+## Where DCKV is required or elected, the system shall vary exhaust fan and makeup air fan speed through variable-frequency drives in response to optical and temperature sensors that detect cooking activity.
−## DCKV sensors shall be zoned to the cooking-equipment layout so that the fan reduces speed only when the equipment under a given sensor zone is idle; sensors placed over a cold zone that does not track the active fryers or broilers will not modulate correctly. {note}
+## DCKV sensors shall be zoned to the cooking-equipment layout so that the fan reduces speed only when the equipment under a given sensor zone is idle; sensors placed over a cold zone that does not track the active fryers or broilers will not modulate correctly.
## The DCKV submittal shall show the sensor zones overlaid on the cooking-equipment layout so that sensor-to-equipment correspondence can be verified before installation.
−## At reduced cooking load the exhaust and makeup air fans shall turn down together so that the design pressure relationship between the kitchen and adjacent spaces is maintained across the operating range. {note}
+## At reduced cooking load the exhaust and makeup air fans shall turn down together so that the design pressure relationship between the kitchen and adjacent spaces is maintained across the operating range.
```datasheet
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# Testing {toc}
−## Field testing and balancing of the completed kitchen exhaust and makeup air system shall be performed under [[sync/testing-adjusting-and-balancing]], and this section establishes the acceptance criteria to be verified. {note}
+## Field testing and balancing of the completed kitchen exhaust and makeup air system shall be performed under [[sync/testing-adjusting-and-balancing]], and this section establishes the acceptance criteria to be verified.
## Measured exhaust airflow at each hood shall be within ±10% of the scheduled value.
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## Grease duct material and listed factory-built duct shall be stored off the ground and kept dry and free of debris and oil so that welds and listed joints can be made clean.
−## Stainless-steel surfaces shall be protected from contact with carbon steel during storage and handling to prevent ferrous contamination and subsequent rust staining of the finish. {note}
+## Stainless-steel surfaces shall be protected from contact with carbon steel during storage and handling to prevent ferrous contamination and subsequent rust staining of the finish.
# Warranty {toc}
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## Exhaust fan and makeup air unit manufacturers shall provide their standard equipment warranty, and the DCKV control system shall carry the manufacturer's controls warranty.
−## The warranty shall cover the grease-tight integrity of the hood, duct, and fan assembly, including weld and joint failures that permit grease leakage. {note}
+## The warranty shall cover the grease-tight integrity of the hood, duct, and fan assembly, including weld and joint failures that permit grease leakage.
# Spare Parts {toc}
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- One set of fan and MAU drive belts (belt-driven)
```