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  1. #1
    Join Date
    Jun 2009
    Posts
    59
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    Whats the best way to balance an exhaust hood / make up air for comm. kitchen??

    Looking for the best way to balance an exhaust hood and make up air..

    It is in San Francisco and the restaurant its self has a large air handler with chilled water for cooling that is constantly running in economiser mode wich I need to factor in on balancing some how also has a small make up air on roof and exhaust fan belt drivenhave no numbers on hp or rpm yet need a permit just to get on roof of establishment I also know I will need possibly new pulleys any info will be greatly appreciated on the basics of balancing a hood

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  3. #2
    Join Date
    Jul 2009
    Location
    Fort Pierce, FL
    Posts
    15
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    Overall, the restaurant should be positively pressurized. It sounds like the hood has both a supply and exhaust fan. Typical exhaust values for a commercial hood are around 100 CFM per square foot, but could be less depending on what equipment is below the hood. The supply fan should bring in about 80 to 90 percent of the air being exhausted. With the kitchen / hood area being kept negatively pressurized to contain cooking odors, additional make-up air should be brought in through the air conditioning system to pressurize the restaurant. This outdoor air quantity shall be determined based on occupancy ventilation rates as per ASHRAE 62.1, or what is required to interact properly with the hood system - whichever is greater. Of course, too much outdoor air shall not be brought in as to overload the existing air conditioner's capacity.

    A Test & Balance firm, and a local Mechanical Engineer may prove valuable in preparing a good set of plans to work from.

  4. #3
    Join Date
    Nov 2014
    Location
    Gastonia NC
    Posts
    45
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    MUA in CKV for dummies, book needed.
    I know this is an old post as well, but I need advice on a heated mua by captive aire.. the kitchen stays in neg pressure. Pulling doors open in kitchen and making doors hard to open from outside. Also, causing some insulated spiral in dining area to sweat. Pulls all a.c. out..Has two 12" returns in kitchen plus 6 : 8-10" supplies. Hood fans are RDUS U2245CA 5ho 208 3phase. MUA is an A2-D.250-G15 with a 5 hp 208 3oh an has a 2" perforated return plenum sorta like ait curtain. Is the voyagers on the roof closing the dampers preventing any extra mua? Removed plenum perforations and of course the air wooshed by and significant helped.. it still never ended the problem. More mechanical mua? Or just more fresh air intakes ? Checked all belts on all units ..filters too. They are 4 years old an very well kept. Ideas on solving this neg pressure in a timely manner ? The condition only exists when fans are running. Mua is wired to ex fan. Moved over to commercial service a year ago from 20+ yrs in residential. Reading ckv(commercial kitchen ventilation) but not getting far they want it fixed yday. I should know this stuff who said hvac without the v is just a hac? S..o...S

  5. #4
    Join Date
    May 2011
    Location
    Las Vegas, Nevada
    Posts
    349
    Post Likes
    It did nothing to remove the perforated supply plenum. You do feel the air now because it's no longer evenly distributed. Reinstall the double perforated panels. The issue is with the air balance. 95% sure of this. Was a certified air balance performed 4 years ago? Did someone speed up the exhaust fan to overcome dynamic effects? Did someone shut the economizers on the RTU's that can sometimes account for 20% of the MUA?

    Give me the job number on the manufacturer's tag and I will tell you what I can about this specific job.
    "Quality is never an accident; it is always the result of intelligent effort. The bitterness of poor quality lingers long after the sweetness of low price is forgotten" --- John Ruskin

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