Air Flows

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Sorry for all of the questions recently on this list, but this is the first serious modelling attempt I am trying with eQuest.

I have a constant volume, 100% OA unit serving patient rooms and corridors? in a long term care facility.? I have set the airflow for the unit at 7,500 cfm.? When I look at the SV-A report, the airflow is showing at 9,090 cfm.? I then tried going into each individual sub-zone and setting the airflows.? The sub-zones airflows in the SV-A report are higher than what I have entered, and the total airflow still remains at 9,090. I am thinking perhaps I have picked the wrong system.? I assumed I could use a packaged single zone for this case.? Perhaps I should be using a different system type???

The other part of the question is how do I model the fact that is 100% OA?? Th only reasonable solution I have found is to have the exhaust air in each zone track the supply flow.? It is also asking for either static pressure and efficiency, or kw/cfm.? As the exhaust is at the unit itself via heat recovery using a heat pipe, I am not sure what I should be entering here, as the fan details would be entered at the unit itself.? Thanks in advance for any help.?

Brad Robinson

Brad Robinson's picture
Joined: 2011-09-30
Reputation: 0

Because the unit is discharging the relief air and not individual room
exhaust fans, you should leave all exhaust fans out of the picture. Make
sure you set the unit to be minimum of 1.00 ratio of outdoor air as well, to
ensure that the unit is 100% OA.

I would also check your elevation coefficient, this could be the cause of
the increased supply air numbers you are seeing (but for the rather large
increase you are seeing, something else may be causing issues as well). I
typically see values less than 10% for elevation values (at 1.10, would make
your 7,500 cfm unit become 8,250 cfm).

I'm sure others will have good ideas as well.


rdh4176's picture
Joined: 2011-02-14
Reputation: 0

The increased airflow is probably due to a system sizing ratio greater than


No Username provide's picture
Joined: 2011-09-30
Reputation: 200

because the airflow you input is based at sea level. if you input 1,000
cfm and your project is in tucson it will be multiplied by an altitude
correction factor of 1.08. rio rico, az has an altitude correction
factor of 1.14. this is for all air flows you manually input. exhaust,
return, supply. check your .inp file near the top & it will have a line
telling you what the altitude correction factor is. divide your input
cfm by this number so when it multiplies it back out the simulation uses
the cfm you want it to, if that's your goal.

Patrick J. O'Leary, Jr.'s picture
Joined: 2011-09-30
Reputation: 200