Results 1 to 10 of 10
  1. #1

    Rooftop central unit vs makeup

    What is the main difference between a rooftop central unit and a makeup unit?

  2. #2
    Join Date
    Jan 2009
    Location
    Indiana
    Posts
    3,228
    make up unit takes in fresh air to replace air that is being exhausted out of the building by another means...i.e. exhaust fans, kitchen hoods, industrial ovens

  3. #3
    Generally speaking, wouldn't the central unit be capable of compensating for exhaust fans, kitchen hoods, industrial ovens?

    The makeup is more than just a fan, it can heat or cool the air right?

  4. #4
    Join Date
    Jan 2009
    Location
    Indiana
    Posts
    3,228
    Quote Originally Posted by guitarboyled View Post
    Generally speaking, wouldn't the central unit be capable of compensating for exhaust fans, kitchen hoods, industrial ovens?

    The makeup is more than just a fan, it can heat or cool the air right?
    most in my part of the country are heat only. No a rooftop unit would not be able to supply the amount of air needed in kitchen hoods and industrial ovens.

    an old account we had before the plant shut down had 8 Makeup units with a BTU of 5 million each. air openings where aprox 5' X 12' Would u need one if u just had small fans for bathroom and let say an air brush station...probably not. but only IF the ac units fresh air damper is set up properly

  5. #5
    Join Date
    Jul 2001
    Location
    Southern NJ
    Posts
    1,241
    I think it sometimes just depends on what the architect calls them on the blueprints.

    I also get confused about unit ventilators, cabinet unit heaters, fan coils, air handlers, and a few other names on prints for seemingly identical equipment.
    Ryan
    Maintenance Guy
    -----------------
    naysayer, skeptic, conspiracy theorist

  6. #6
    Therefore, if nothing is sucking important volumes of air out of a room, it won't require a makeup.

    Technically an exact same unit could be used as a central unit in one application and as a makeup in an other?

  7. #7
    Join Date
    Mar 2004
    Location
    CHICAGO SUBURBS
    Posts
    464
    RTU's return air from space and recirc. it, only adding a minimal amount of makeup (outside) air. When you have need for a lot of air exchange I.E. auto painting or some industial process or a commercial kitchen, you are removeing a great deal of air that needs to be replaced to support human life, combustion of other equipment, and space positive pressure. I work in buildings that have both RTU's and make up units in the same zones. Winter temps in Chicago are cold and as the gentleman from Indiana said, if you are removing alot of exhaust from a building space and replacing as much or more in the winter around here, you better have some big burners on your make up air unit. Usually direct fire burners.
    Some people swear by me and some at me

  8. #8
    Join Date
    Jul 2009
    Location
    eastlake,ohio
    Posts
    73
    Most package rooftops at design temp can't handle more than 30% outside air,and to keep fresh air design for people load and exhaust loss,whatever reason a make-up unit would be used.We do alot of kitchen exhaust canopy's and some jobs we dump fresh tempered air into kitchen area,about 80% of exhausted air ,and on some jobs we close loop and dump in front and in and at the floor of the kitchen hood.This stops the loss of your conditioned air from the dining room,and backdraft of flue fumes.(and flies don't come in the front door at 120 mph)

  9. #9
    What if a relatively small new addition is added to an existent building. Would the unit providing air be called a secondary central unit or a make-up?

  10. #10
    Join Date
    Jan 2009
    Location
    Indiana
    Posts
    3,228
    i think our definitions are mixed up...give us your definition of each and then we will go from there. like mentioned before ive seen units named different things by architects.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event