Commercial Kitchen Make up air Fan
Commercial Kitchen Make up air Fan
(OP)
Hello guys.
My office designed a kitchen expansion where a new 12x4 type II hood was installed. It included a thru roof Exhaust fan and a Make up air unit. City came back with a few revisions. They want us to show air balance on schedule. I consulted with a mechanical engr and proposed to show a diagram where MUAF is suplying the actual hood (inside). To me this does not make sense. I have always shown supply diffuser in the vicinity of the hood and it has been approved and built. Could you provide your feedback?
Ps. Curious guys asking what is an SE dealing with a Kitchen exhaust systems. Please refrain. I dont have the answer. Hahah :0)
My office designed a kitchen expansion where a new 12x4 type II hood was installed. It included a thru roof Exhaust fan and a Make up air unit. City came back with a few revisions. They want us to show air balance on schedule. I consulted with a mechanical engr and proposed to show a diagram where MUAF is suplying the actual hood (inside). To me this does not make sense. I have always shown supply diffuser in the vicinity of the hood and it has been approved and built. Could you provide your feedback?
Ps. Curious guys asking what is an SE dealing with a Kitchen exhaust systems. Please refrain. I dont have the answer. Hahah :0)





RE: Commercial Kitchen Make up air Fan
RE: Commercial Kitchen Make up air Fan
You can either put a schedule on your drawing and save your time, or send him a letter asking about the code reference he is using, city job is to make sure that your work conforms to the code, not to evaluate your design or arrange your drawings.
RE: Commercial Kitchen Make up air Fan
RE: Commercial Kitchen Make up air Fan
RE: Commercial Kitchen Make up air Fan
RE: Commercial Kitchen Make up air Fan
It sounds as though a registered mechanical P.E. did not design the system, so city is simply trying to verify the new expansion hasn't thrown off the building's overall balance and more importantly relative pressurization to the outdoors.
It's been awhile since I've designed or worked with a kitchen hood that includes exhaust and make-up air, but I seem to recall the exhaust air being greater than the make-up air (~10%). The reason for this would be to ensure that hood is always exhausting grease laden air instead of pushing that air into the kitchen (bad for people's heatlh). This becomes important to the overall building's pressure (balance) because if the hood exhaust is greater than all other sources of outside air, the building will go 'negative'. This is bad because 1) exterior doors can become "heavy" and hard to open (possibly hindering building egress if the doors swing outward); 2) a positively pressurized building keeps mold causing humidity out. Note that too much positive pressure can be bad too causing unwanted stress on the structure (think balloon), outward swinging exterior doors may not close or whistle.