# Ventilation systems in commerical restaurants



## Bryant (Feb 21, 2019)

Greetings,
As a first time posting, I had a general question regarding the components that make up the ventilation system in a restaurant/Kitchen environment. My understanding is there are 4 parts to an effective ventilation system.
1. ventilation hoods
2. heat exhaust hoods
3. grease exhaust hoods
4. exhaust fans
 Is this an accurate representation of what entails an effective ventilation system?
And as a ventilation hood is to exhaust grease and heat from work areas , is it a different mechanism than an actual grease hood, or is one and the same? I'm thinking the ventilation hood captures work areas  and the grease hood is directly over the cooking apparatus

thanks


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## cda (Feb 21, 2019)

Welcome on your first post


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## cda (Feb 21, 2019)

Yeah kind of 
Basically two types of hoods;::;



HOOD.An air intake device used to capture by entrapment, impingement, adhesion or similar means, grease, moisture, heat and similar contaminants before they enter a duct system.

Type I.A kitchen hood for collecting and removing grease vapors and smoke. Such hoods are equipped with a fire suppression system.

Type II.A general kitchen hood for collecting and removing steam, vapor, heat, odors and products of combustion.


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## rgrace (Feb 21, 2019)

Hi Bryant, and welcome.

Forgive me, but I do not completely understand what you are questioning, so some specifics. I am in a jurisdiction that has adopted the 2015 International Mechanical Code (IMC), so that is where I get my information from related to ventilation systems. Here is a link if you need access to this code: https://codes.iccsafe.org/category/I-Codes?year[]=2015&page=1

I do not believe that the four parts that you listed in your post could actually be considered an accurate representation of an effective ventilation system. I'm not certain what a "ventilation hood" really is. The IMC has definitions for "ventilation, ventilation air, and air distribution system." cda provided the definition for "hood." Can you elaborate on what exactly you are working on and what you are looking to define? Perhaps more detail can enlighten me and I can assist. Thanks !


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## rgrace (Feb 21, 2019)

Perhaps a better link since you're from VA 

https://codes.iccsafe.org/content/VMC2015


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## mtlogcabin (Feb 21, 2019)

Every exhaust ventilation system will need to include makeup air and most geographical areas in this country will require the make up air to be conditioned


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## ADAguy (Feb 21, 2019)

mtlogcabin said:


> Every exhaust ventilation system will need to include makeup air and most geographical areas in this country will require the make up air to be conditioned


Thank you for bringing this to his attention. No makeup, no fresh air exchange.


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## Bryant (Feb 22, 2019)

Sorry for the delay, neck deep in plan review. also thanks for the responses!
Really what I was after is the balancing act of exhausting restaurant air and balancing it out with outside fresh/makeup air? As I understand it, difficult at best to compensate for every CFM in this set up. How many times have you been in a restaurant and smelled something good or bad?
in attempting to define the components in the exhaust spectrum, I wanted to identify the differing exhausting mechanisms. In this case grease hoods type I steamers and dishwashing equipment type II and other exhausts such as bathrooms and or smoke areas and the returns for any heating and cooling capacities.  
To say the least a daunting task to calculate all the differing variables to balance out the system. The burden is on the designer to show compliance and as a plan reviewer, being able to digest it. And to throw gas on the fire, having to deal with the IECC demand control ventilation requirements.

Informative site !
thank you


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## JPohling (Feb 22, 2019)

Bryant,  You should consider becoming a sawhorse as you can see the knowledge here and willingness to share is paramount.


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## Bryant (Feb 22, 2019)

I will be coming back! In my locale, we have to transverse over the five disciplines of plan review, building, electrical, plumbing, mechanical/gas, & energy codes.
Staying busy is an understatement.


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## cda (Feb 22, 2019)

Bryant said:


> Sorry for the delay, neck deep in plan review. also thanks for the responses!
> Really what I was after is the balancing act of exhausting restaurant air and balancing it out with outside fresh/makeup air? As I understand it, difficult at best to compensate for every CFM in this set up. How many times have you been in a restaurant and smelled something good or bad?
> in attempting to define the components in the exhaust spectrum, I wanted to identify the differing exhausting mechanisms. In this case grease hoods type I steamers and dishwashing equipment type II and other exhausts such as bathrooms and or smoke areas and the returns for any heating and cooling capacities.
> To say the least a daunting task to calculate all the differing variables to balance out the system. The burden is on the designer to show compliance and as a plan reviewer, being able to digest it. And to throw gas on the fire, having to deal with the IECC demand control ventilation requirements.
> ...




Write a requirement for a balance test and a copy of the results


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## rgrace (Feb 25, 2019)

Bryant, you are correct, and I agree with your assessment, a balanced ventilation system can become complicated with all the different variables available to the design community. Intermittent or continuous use, demand control ventilation, variable speed control for hoods, infiltration/exfiltration, gravity means (barometric duct dampers), mechanical means, positive and/or negative provisions for specific spaces, mix in combustion air and venting requirements and you have a complicated cornucopia of balancing. Then we throw in code language statements like "the amount of supply air shall be approximately equal to the amount of return and exhaust air" and "the system shall not be prohibited from producing a negative or positive pressure" (403.1 _ventilation air_), "the amount of makeup air supplied to a building from all sources shall be approximately equal to the amount of exhaust air for all exhaust systems in the building" (508.1 kitchen _makeup air_) and new to 2015 "the total replacement air airflow rate shall *equal* the total exhaust airflow rate plus the net exfiltration" (508.1.2). Exfiltration ! I don't have time or resources to calculate total exfiltration or infiltration. This section also requires that a "design outdoor air balance" schedule or diagram be submitted with the design plans. 403.3.1.5 states that ventilation systems shall be balanced by an _approved_ method. That means AHJ approved method. My method would be to ask the design professional to provide an air balance schedule on projects that contained complicated ventilation system designs and do spot check verification on the figures they provided. If I saw something grossly exaggerated, I would question it. VCC 109.3 _Engineering details_ permits a plan reviewer to request this information when not directly quoting 508.1.2.


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## steveray (Feb 25, 2019)

Usually you want the kitchen to be slightly negative......Then they don't clean the grease filters and it gets easier to open the doors...


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## Bryant (Feb 25, 2019)

quick question concerning exhaust systems in the above example, late in the day my mind is mush now! commercial dishwashing equipment. Is this not considered a laden vapor e.g. heat, steam and odor and in that light requiring a type II hood? 
thanks


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## cda (Feb 25, 2019)

Type II.A general kitchen hood for collecting and removing steam, vapor, heat, odors and products of combustion.


Yes

Which edition of IMC do you have adopted????


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## rgrace (Feb 26, 2019)

Bryant said:


> quick question concerning exhaust systems in the above example, late in the day my mind is mush now! commercial dishwashing equipment. Is this not considered a laden vapor e.g. heat, steam and odor and in that light requiring a type II hood?
> thanks



Maybe, depends on the dishwasher and the design. 507.3 states a Type II hood be installed above dishwashers that produce heat or moisture. There are dishwashers out there that sorra don't. They capture the heat and moisture and either drain it or recycle it. Also contained in 507.3 is the provision to incorporate the additional heat and moisture load of the dishwasher into the HVAC system design.


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## Bryant (Feb 26, 2019)

cda said:


> Type II.A general kitchen hood for collecting and removing steam, vapor, heat, odors and products of combustion.
> 
> 
> Yes
> ...


still in VMC 2012, until September


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## cda (Feb 26, 2019)

Oh Vermont mechanical code

More than likely VMC is similar to IMC


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## rgrace (Feb 26, 2019)

I'm sure Bryant meant the Virginia Mechanical Code, not Vermont (link provided in post #5). Adoption date for the 2015 codes was September 4, 2018. Virginia allows a one year grace period during the code adoption process, allowing the use of the 2012 editions until September 3, 2019, provided permit application is submitted during that period. The grace period is _intended_ for project designs that are substantially completed at the time of adoption, so that designers don't have to start from scratch with a new code edition. It is not intended for the startup of a new project design after September 4, 2018. If a new project design is started after that date, it should be based on the 2015 codes.


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## rgrace (Feb 26, 2019)

[retract this post]


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## Bryant (Feb 27, 2019)

rgrace said:


> I'm sure Bryant meant the Virginia Mechanical Code, not Vermont (link provided in post #5). Adoption date for the 2015 codes was September 4, 2018. Virginia allows a one year grace period during the code adoption process, allowing the use of the 2012 editions until September 3, 2019, provided permit application is submitted during that period. The grace period is _intended_ for project designs that are substantially completed at the time of adoption, so that designers don't have to start from scratch with a new code edition. It is not intended for the startup of a new project design after September 4, 2018. If a new project design is started after that date, it should be based on the 2015 codes.


correct Virginia Mechanical Code which is referenced via the USBC Uniformed statewide building code.


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## MFisc (Feb 27, 2019)

Bryant said:


> correct Virginia Mechanical Code which is referenced via the USBC Uniformed statewide building code.



Damn good to know.

_______________________


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## chris kennedy (Feb 27, 2019)

MFisc said:


> Damn good to know.
> 
> _______________________



Welcome to the forum.

This is not a place to just drop links.

Please feel feel to offer information pertaining to the thread and ask questions.


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