Homemade makeup air system

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Smith76
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2017/07/14 10:50:51 (permalink)

Homemade makeup air system

Anyone with knowledge of this let me know what you think. I have been thinking about make up air for my truck and this is my what I have come up with. I am mounting a 1200cfm centrifugal duct fan under the truck and then piping it to vents under the hot line. My hood vent fan and this duct fan are both variable speed so I believe I can match them up so it all equals out. Thoughtsm
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    Blakkmoon
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    Re: Homemade makeup air system 2017/07/14 14:48:44 (permalink)
    K
    Gotta ask because I am working on the same kind of thing right now...
    1. Hood - commercial type?
    2. You have a fan for your hood?  Side discharge or big mushroom fan?
    3. This fan under the truck...  blows INTO the truck? or sucks air out?
    #2
    Smith76
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    Re: Homemade makeup air system 2017/07/14 15:07:17 (permalink)
    I have a 10 foot low proximity hood vent from ventilation direct with a mushroom fan capable of 1500 cfm which i have turned down some. The duct fan is 1200cfm, mounts under the truck and blows into the truck under the hot line equipment.
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    Blakkmoon
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    Re: Homemade makeup air system 2017/07/14 15:48:32 (permalink)
    .
    post edited by Blakkmoon - 2017/07/15 10:08:36
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    chefbuba
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    Re: Homemade makeup air system 2017/07/14 16:16:42 (permalink)
    I worked on catering trucks for seven years when I did movie catering. 24' kitchens, 36' fifth wheel pulled by a toter, and my own 20' trailer for seven years.
    Open a window, makeup air is a waste of time and money. AC is also a waste,unless you have an ice cream truck in the tropics, it all goes up the hood.
    Just ma two cents worth from someone that's been doing it for a while.
    #5
    edwmax
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    Re: Homemade makeup air system 2017/07/14 18:47:25 (permalink)
    Smith76
      ... I am mounting a 1200cfm centrifugal duct fan under the truck and then piping it to vents under the hot line.  .... Thoughtsm



    I think the hot line equipment will disrupt ( as well as personnel standing over the vents) the air flow causing the air to blow though out the truck and with it draw smoke and heat from the hot line and away from the hood.   You need a clear path for this to work.    This is why commercial hoods with makeup air does it with an 'air curtain' at the front of the hood.
     
    So if you want to build your own 'make air' system do it with an air duct at the ceiling just in front of the hot line & hood.  Point the makeup air vents (air flow) towards the back wall & hot line at grill top level.
     
     
    #6
    RodBangkok
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    Re: Homemade makeup air system 2017/07/14 20:26:21 (permalink)
    We consistently used the Backwall make up air model referenced in the study referenced below.  I have used this when we designed systems for conveyor fryer lines in commercial applications.  
    So when it came to our food trucks as we had an open to outside wall I used basically the same concept but instead of bringing the inlet down the back wall we just put the fan along the floor.  I used two or three bathroom vent vans with louvers set into the walls so the louvres were flush then put a screen over that.  Frankly I don't remember how I calculated the cfm right now but they worked good for us.  You need to be aware of airflow directly into any gas manifolds that may effect the performance of gas heating equipment.
     
    I believe I referenced this somewhere in the forums in the past, but in case I didn't here's a useful study performed on the types of makeup air systems, that's what I based our designs on when it came to our first commercial design.
     
    I does a good job of comparing the different types of makeup air supply, it also warns against the use of short circuit type vents, which I found there are a lot of out there.
     
    I have used this when we designed systems for conveyor fryer lines in commercial applications.  
     
    As far as efficiency in a small open food truck, all I can say is its providing its own outside air from within the natural flow of air from bottom to top vertically thru the equipment and directly out the top, I don't think there's a more natural air flow than that.  (That helped influence me when we took the plunge the first time into doing back wall in a commercial system.)  
     
    Keep any A/C you have focused on the people, your probably not going to efficiently cool the entire kitchen, but by keeping a blast of cool air on the employees it helps a lot.  Speaking from a guy that has done a shift or two in Bangkok.
     
    Referenced article:
     
    http://www.energy.ca.gov/...-04-10_500-03-007F.PDF
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    Blakkmoon
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    Re: Homemade makeup air system 2017/07/15 10:13:47 (permalink)
    Thanks RodBangkok
    I knew I read that somewhere. 
    Almost as much fun to read as the NFPA96.
     
    I think it was you that helped to influence the way I am trying to model MY air exchange.
     
    Although, as the study suggest, even a small disruption in airflow will mess with the airflow.
    So people, fans, air conditioners, open windows and doors, will all affect it.
     
    But hey, we can only do what we can do.
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    Inkys
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    Re: Homemade makeup air system 2017/09/07 11:51:55 (permalink)
    The whole point of make up air is for places with tightly sealed spaces (created by modern insulation and such) so the hood isn't trying to pull a vacuum on the interior air space. I see no reason on a food truck. Just open a window
    #9
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