A value of 0.001 in the MIN-AIR-SCH activates an air-side economizer, allowing a unit to provide cooling by varying the volume of outside air.
In a dedicated outdoor air system (DOAS) or other air-side system with 100% outside air, hourly values of the MIN-AIR-SCH should be 1.0.
What about a 100% OA system with variable flow?
I think the hourly values in the MIN-AIR-SCH should still be set to 1.0 for all hours. Hourly reports in my tests show the flowrate increasing above the MIN-FLOW-RATIO during cooling conditions, while the OA is still at 100%.
If I use 0.001 in the MIN-AIR-SCH, the hourly OA% drops way below 100%.
Does this seem right?
Thanks,
~Bill
Custom hourly reports can show the flowrate and OA% of air handlers. This is a typical BDL input for hourly reporting of total system supply air flow rate and OA ratio, in this case for a system "RVU-2":
"RVU-2 Hourly Block" = REPORT-BLOCK
VARIABLE-TYPE = "RVU-2"
VARIABLE-LIST = ( 17, 39 )
..
"Hourly Report" = HOURLY-REPORT
LIBRARY-ENTRY "Hourly Report"
REPORT-BLOCK = ( "EM1 Hourly Report Block", "FM1 Hourly Report Block",
"RVU-2 Hourly Block" )
..
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
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bbishop at pathfinder-ea.com
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