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
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.
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)