VAV Diversity in Fan Sizing
VAV Diversity in Fan Sizing
(OP)
Are there any rules of thumb on the amount of air flow diversity that can be expected in a a VAV system? In other words, how much below total cooling load design can the airflow be lowered? I have seen systems with a wide variety of percentages below design - anywhere from 0% to 25%
My thinking is that the only variable you can count on is the sun exposure throughout the day. Unless you know some internal diversity that is guaranteed, it seems to me that the sun is the only variable you can count on.
So I would think that the sun load on the east or west exposure (whichever is smaller) is the only thing that can be safely subtracted from the air flow.
Agree? Disagree? Any other thoughts?
My thinking is that the only variable you can count on is the sun exposure throughout the day. Unless you know some internal diversity that is guaranteed, it seems to me that the sun is the only variable you can count on.
So I would think that the sun load on the east or west exposure (whichever is smaller) is the only thing that can be safely subtracted from the air flow.
Agree? Disagree? Any other thoughts?





RE: VAV Diversity in Fan Sizing
RE: VAV Diversity in Fan Sizing
An interesting fact here with year round cooling is strong solar gain in December. My overall loads will be down as the humidity has dropped in the outside air, the ambinet dry bulb drops a bit, but the big difference is the lower dewpoint in december.
However, I need the highest airflow many times in December because of the solar gain especially in office with southern glass.
Up north it would be reduced run time on the heating system, here it is something to look out for in cooling.
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: VAV Diversity in Fan Sizing
RE: VAV Diversity in Fan Sizing
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: VAV Diversity in Fan Sizing
for all these years guys, I've never heard of Elite. Goes to show that you learn soemthing everyday. So, what is Elite?
RE: VAV Diversity in Fan Sizing
RE: VAV Diversity in Fan Sizing
Tell the program it is VAV and will come up with the peak air flow to design around
It is considerably lower than the sum of the peaks option you can do with constant volume
Take the "V" out of HVAC and you are left with a HAC(k) job.