need help with make-up air design

[roberta-aire]

hello

i'm not getting enough make-up air to a commercial kitchen exhaust hood, and i'm trying to size and install a proper supply fan.

my understanding is that the current intake fan, a propeller type 18" fan blade, does not handle much static pressure. i was told i need to replace this fan with centrifugal blower motor. i've been looking at floaire's website (whose equipment is currently on the roof), but i'm not certain which size to go with. any help would be appreciated. below i listed some factors that may be relevant.

it's a job i'm doing for my wife's aunt. unfortunately, my father, a 50 yr. HVAC veteran mechanic, passed away this past year w/ pancreatic cancer. the solution would have been so simple for him! no, i'm not an HVAC mechanic (i guess that's obvious). i did work with him for a number of years, and yes, i wish i picked up more than i did. i hope i've given you enough info to offer me some help.


possibly relevant factors:
current exhaust fan - Belt Drive Centrifugal Upblast Exhaust Fan with 18.75" wheel, 1HP motor,
current supply fan - Economy Make-Up Air Fan with an 18" wheel, 1/3HP motor
15 - 20 ft. of 12" flex duct supplying make up air from roof
4 x 8 hood w/ 2 - 20 x 8 make up air grilles
restaurant space - 600 sq.ft. w/ 10ft. ceiling

thanks again.
mike

[maddfridge]

firstly sorry to here about your father

i am in the uk so really cannot comment on the us but here we have standards which you can refer to ie the number of people in a space dictates fresh air conmbustion and flow rates

Is there a local standards library near you or you could look on the net

Good luck

[cxagent]

Find the test adjust and balance report on that kitchen. It will list the airflows through each fan/hood. If there is no TAB report, getting one is where you need to start.