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Makeup air for hood

C

Charlie M Peterson

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Joined
Aug 26, 2019
Messages
3
Location
Palatine
I am attempting to help out a relative that owns a restaurant. She has two hoods in the kitchen and each has it's own exhaust fan. The issue is makeup air. There is no unit on the roof to supply makeup air for either hood. The new hood was installed with the make up air duct sticking up into the attic area and is just open. The type of hood is called a short circuit I believe. The makeup air comes in right at the inside front of the hood.

The older hood has the makeup air coming from the side or I believe it is called a side curtain. It is connected to duct work that draws from the ceiling in the dining area but it is a passive system.

This lack of makeup air has led to all kinds of problems including difficulty opening outside doors into the restaurant because of negative pressure inside the restaurant, back drafting, air conditioning and heating issues, etc.

My questions are many. Does the incoming air if we install a powered intake unit ducted to the hoods need to have tempered air? Or can I just pull outside air in as it will be exhausted immediately out again through the hoods.

How far from the exhaust fan should the makeup air unit be located? I do not want to contaminate the fresh incoming air with the exhausted air.

If the exhaust fan is 2300 cubic feet a minute and the makeup air unit is 1600 cubic feet a minute, does this work? The new hood manufacturer states this is the makeup unit matched with the hood installed.

The old hood has a side curtain makeup air location pointed straight down at the floor. I am thinking if air from the outside is blown in straight down, it will need to be heated or cooled depending on the season. Or can a deflector be installed to redirect the makeup air back into the hood?

Thanks for anyone who can assist me with these questions.
 
Welcome

Which state is this in??

I can do this one

“How far from the exhaust fan should the makeup air unit be located? I do not want to contaminate the fresh incoming air with the exhausted air. ””

Ten feet and ten feet to property line

If I understand right this is normal :::


“”The old hood has a side curtain makeup air location pointed straight down at the floor. I am thinking if air from the outside is blown in straight down, it will need to be heated or cooled depending on the season. Or can a deflector be installed to redirect the makeup air back into the hood?””
 
Best suggestion get a good hvac company that deals with kitchen hoods to check everything
 
Any suggestions on finding a good HVAC company that deals with restaurant hoods? There are a lot of HVAC companies out there. However finding one that is knowledgable in restaurant hoods is the key.
 
Welcome

Repeat

Talk to the company that does the extinguishing system inspection

Ask them for three or four companies
 
Yes the make up air needs to be tempered. Now that can come from the HVAC system which sounds like that is part of the problem or it can be an independent system or a combination of both.
FYI
Using the HVAC as part of the tempered make up air is very expensive on the utility bill for heating and cooling and a sure way to cut into the profits which may contribute to the ultimate closure of the restaurant.

2012 IMC
508.1 Makeup air.
Makeup air shall be supplied during the operation of commercial kitchen exhaust systems that are provided for commercial cooking appliances. The amount of makeup air supplied to the building from all sources shall be approximately equal to the amount of exhaust air for all exhaust systems for the building. The makeup air shall not reduce the effectiveness of the exhaust system. Makeup air shall be provided by gravity or mechanical means or both. Mechanical makeup air systems shall be automatically controlled to start and operate simultaneously with the exhaust system. Makeup air intake opening locations shall comply with Section 401.4.
508.1.1 Makeup air temperature.
The temperature differential between makeup air and the air in the conditioned space shall not exceed 10ºF (6ºC) except where the added heating and cooling loads of the makeup air do not exceed the capacity of the HVAC system.

401.4 Intake opening location.
Air intake openings shall comply with all of the following:
1. Intake openings shall be located a minimum of 10 feet (3048 mm) from lot lines or buildings on the same lot.
2. Mechanical and gravity outdoor air intake openings shall be located not less than 10 feet (3048 mm) horizontally from any hazardous or noxious contaminant source, such as vents, streets, alleys, parking lots and loading docks, except as specified in Item 3 or Section 501.2.1. Outdoor air intake openings shall be permitted to be located less than 10 feet (3048 mm) horizontally from streets, alleys, parking lots and loading docks provided that the openings are located not less than 25 feet (7620 mm) vertically above such locations. Where openings front on a street or public way, the distance shall be measured from the closest edge of the street or public way.
3. Intake openings shall be located not less than 3 feet (914 mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening.
4. Intake openings on structures in flood hazard areas shall be at or above the elevation required by Section 1612 of the International Building Code for utilities and attendant equipment.
 
As stated in a previous post, the makeup air shall be approximately equal to the exhaust air. If not, then you could have issues with opening doors, which have pull force requirements.

Inspected a new small restaurant and the owner did not want to put the make-up air unit in, just wanted to rely on a screen back door. Did a test with the hood running and all doors closed as in winter conditions. It was very difficult to open the egress doors and they would have caused serious injury if closed and someone was in the door way.
 
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