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Originally Posted by antstudio  What is the recommended number of air exchanges per hour? And is my calculation correct below? |
I have stated before and will state again...... calculations based on air exchanges per hour just do not make sense.....
Tke a room 10 x 14 with an 8' ceiling - based on your calculations that room would have 6 exchanges oer hour for a total of X cubic feeet of air per hour (the actual number is not relevant)
Now - if we decide to make the ceiling 18' high - we suddenly need more than twice as much air?
Why?
We won't fit one more person in the room than we could before - and they are the ony thing we need to worry about dying if they don't get enough air...........
Fresh air supply should be provided based on the maximum number of people who will be in the room........ and then that number should be multiplied by a factor you feel is reasonable for the purpose.
As an example of this - the Internation Mechanical Code sets a minimum cfm per person in a music room of 15 cfm.
They have different rates for dfferent occupancies - but this is what they set for music rooms.
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I have a small sound "isolated" mixing/recording room-in-a-room. Fully sealed with a duct inlet and outlet on opposite sides for air circulation. I'm planning my air exchanger, an external fan installed in an insulated enclosure (plenum), connected via a vent duct, to vent old air out, thus pulling new air in from the enclosing room (garage).
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I do not know where you are from - but in the US this is a HUGE code violation.....
Fresh air is just that - fresh air - and it is required to be pulled from OUTSIDE the building - it is not allowed to be pulled from anywhere inside -
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Mostly it will be just me in the room, although it would be nice to record a guest performer once in a while.
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So around 30 cfm is what you really need......
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I was hoping to use a small, quiet computer case type fan (or maybe a pair of fans), but I'm not sure this is realistic. Really want to keep the noise down at all costs, since the room is close to silent right now (e.g., the computer lives outside the room).
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Computer fans will not CANNOT get the job done......
Although they might move air in the volume you are looking for - they do not have any capacity to overcome static pressue - picture that computer cases do not block air flow at all - what do you have - 15" or so from the front intake to the rear exhaust - usually only a few inches one way or another above one another.
Nope = you are going to have to decide what you want to supply for volume,,, then determine how much backflow pressure exists with your ductwork the way it is - then size a fan according to those criteria - and look for the best rating in sones that you can find.
Rod