Hello all:
I am trying to simulate zero outside air. I set the min OA on the systems
tab to zero, economizer to fixed fraction, there are no OA numbers at the
zone level. I would assume this will give me zero OA but when I look at the
hourly variables (ratio of outside air to supply flow - Var 39, and the
minimum OA damper position - Var 80) they vary from 0.21 to 0.56.
What am I missing? Any pointers helpful.
-Rohini
OA hourly data
Apr 19, 2011
Rohini, Try setting all the zone level outside air fields to the
smallest number you can enter.
Kamel Haddad
Kamel, Bill,
Thanks for the reply. I changed the OA cfm for all the zones to 0. Now in
the SV-A report the zone OA is showing as zero but the system OA ratio is
0.2 and the custom hourly report variables (ratio of outside air to supply
flow - Var 39, and the minimum OA damper position - Var 80) are still
varying from 0.21 to 0.56. Not sure from where eQuest is getting 0.2 value
or these other values in the hourly report.
Does VAV have a default minimum outside air that cannot be overwritten?
Thanks
-Rohini
Rohini, I meant to indicate to use the smallest number that is > 0. A
zero value will make DOE-2 use the default.
Kamel Haddad.
Rohini:
Since there is no such thing as a damper that does not have a leakage value,
perhaps eQuest is factoring that in. Can you just remove the economizers?
Paul Diglio
I changed it to 0.01. No change in the results. Also the default at zone
level is 0.
-Rohini
I have set the OA control to fixed fraction.
-Rohini
Attached are the files. I am looking at RTU1 system.
Thanks
-Rohini
At the system level in flow parameters supply air is set to 20,000 cfm
but return is set to 16,000 cfm. Difference is set as OA. Clear the
return air flow field and you will get 0 OA air flow.