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New Restuarant A/C sizing

More to considor:
Type of cooking
fuel for cooking appliances, gas, electric or solid fuel
type of appliances, fryer, charbroiler, range, wok, grill
CFM exhausted by cooking hood and dishwashing hood
CFM and location of make-up air
Distance between exhaust termination on roof and intake air
Type of diffuser on make-up air
Is kitchen open or closed design.

The more I study kitchen air flow, the more I have come to realize the whole HVAC-intake-exhaust needs to be a complete integrated package. Go to captiveaire.com or greenheck.com or upyourstack.com or jdpinc.com/pdf/CKFquantified.pdf or IMC sections 509
or products3.3m.com and do a search for duct insulation.

Douglas Hicks
General Fire Equipment Co of Eastern Oregon, Inc

Comments

  • fast5frogfast5frog Member Posts: 21
    Sizing new restaurant for a/c

    Hey guys...I have never done any commercial work, but as a favor to a friend of mine, I am going to attempt it...hopefulle with some of your help. It is a 2000 sqft open area with a 337 sqft kitchen. My main fear is undersizing the unit. I know you have to compensate for the people (which the max is 92) but I dont know off the top of my head what that number is. Also, with it being an open area, how would you place the return ducts? And with that, I think I need to bring in 2500 cfm of fresh air from the outside as well...Can someone tell me if that is correct? The way I figure it, it should be a 6 ton unit, however, I also have to account for a exhaust fan in an open kitchen. I hope one or more of you fine gentlemen can help me out. After this I promise myself that I will just do residential...Thanks is advance guys. Ron
  • Eugene SilbersteinEugene Silberstein Member Posts: 1,380
    A few questions

    In order to better assist, here are a few questions for you to answer for us:

    Type of restaurant: cuisine etc.

    Freestanding or in a building?

    If in a building, what floor?

    Windows and other fenestration?

    List of cooking equipment?

    Zagat's Rating? (justkidding)

    Exhaust fan rating?

    Number of kitchen personnel?

    List of refrigeration/dishwashing and other heat-generating appliances?

    Location of refrigeration condensing units?

    This should give us a start.
  • don_181don_181 Member Posts: 4
    Thats a

    good start.Most localities require a stamp of approve plans and spec from a mechanical engineer....

    This would be a good time to hire one and pass the cost on to the job.

    Nothing like having another person to help share the burden if things don't go according to plan.

    Good Luck with your project.

  • fast5frogfast5frog Member Posts: 21
    Thanks

    I will review the plans in the morning and write a detailed post for you with all the info you asked for. But thanks again in advance...I really appreciate it guys!
  • Robert O'Connor_12Robert O'Connor_12 Member Posts: 724
    Ron

    What state is this in?

    You need a mechanical engineer to prepare these calculations. The type of structure and use dictate this in you're state's administrative code.

    I'd be quite careful attempting to compensate for the losses you will see from the kitchen exhausters.

    This is not to say you are not capable but merely a determination having stability. More than likely you will find the engineers mistakes and will probably have to correct them for a fee. If by chance you under-estimate the heat or cooling load as the effects of the exhausters are significant, will you be prepared to go to court and explain??



    Robert O'Connor/NJ
  • Empire_2Empire_2 Member Posts: 2,343
    Just some thoughts.

    Some of the restaurants we service have the Make Up Air units and you can allways tell in winter when they do not fire them because of fuel cost, but ever try to open the door when all exhaust fans are on with no MUA? Damn door is tough to open ;-) Plus a great problem with pilots going out to. They can never figure out why.......

    Mike T.
  • John Mills_5John Mills_5 Member Posts: 935
    6 ton total?

    Friend has a 1100 sq ft pizza joint. Block building, minimal wall insulation, attic has 6". West wall all glass. Unit came with 3 tons which barely kept up empty in steamy weather. We added 5 ton cooling only system wired as 2nd stage on the stat. Now he can handle hot weather. Place seats 34. 2 pizza ovens under hood, no MU air, numerous coolers.

    If you look at the average fast food joint. You may find 2500 sq ft but typically 20-30 tons! Judging from the cool & damp some of them get in the summer, that could be oversized. Most units 10 tons & up stage though which helps.
  • TechmanTechman Member Posts: 2,144
    Restaraunt HVAC sizing

    Be careful!Kitchen exhaust fan is a killer on HVAC loads.A properly installed make-up air system is a must.Preferabily the kitchen is seperate from the seating area for figuring out your BTU loads.Duct system should have a hi and low return. AC unit should be 2 or 3 stage with economizer.Same for heat. Also you must take into account the BTU's of thattasty food your friend is selling.Not to many people like to sweat and eat at the same time.Not to many people will return to sweat and eat again.
  • fast5frogfast5frog Member Posts: 21
    finally have it??

    > Be careful!Kitchen exhaust fan is a killer on

    > HVAC loads.A properly installed make-up air

    > system is a must.Preferabily the kitchen is

    > seperate from the seating area for figuring out

    > your BTU loads.Duct system should have a hi and

    > low return. AC unit should be 2 or 3 stage with

    > economizer.Same for heat. Also you must take into

    > account the BTU's of thattasty food your friend

    > is selling.Not to many people like to sweat and

    > eat at the same time.Not to many people will

    > return to sweat and eat again.



  • fast5frogfast5frog Member Posts: 21
    finally have it??

    Ok, heres what weve got so far...we figured out that the cooling load including the max number of patrons (45) two service people, 2500 cfm of make up air will all come out to a 10 ton unit. However, what I am thinking though is, she said that the cooking would be done before or after eating hours. She will only be open for breakfast and lunch. Now this leads me to this question, If the exhaust fan wont be running during eating hours and she is ok cooking in the kitchen with only the exhaust fan running, do I need to take into consideration the MUA? If I do, Like I believe Mike said, the 10 ton unit will have variable speed to compensate for that, right?
  • Empire_2Empire_2 Member Posts: 2,343
    Generally

    MUA is interlocked with full kitchen operation, meaning that when the big stuff is on,(exhaust fans) that's when the MUA can be also be turned on. Doesn't have to be on when light load cooking is being done. Plus I think your system will be staged, not variable speed unless they are going Cadillac. Remember MUA is only there to replace the air that is being exhausted when desired. It does not heat the kitchen in winter, only tempers the supply air in to the kitchen to keep a .01 or .02 positive pressure in the ENTIRE building. Many kitchens have no MUA, so take it with a grain of salt.

    If you have a larger kitchen, A dedicated A/C unit would help for the comfort level in this area. But I think you only have a typical small building of 2 to 3000 sq ft building.

    I hope this make it a-little clearer.

    Mike T.
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