Hi all,
I am modeling a multifamily building where the common spaces are served by PSZ. The OA is provided by a DOAS. I used "AirLoopHVAC:UnitarySystem" for the PSZ and "ZoneHVAC:OutdoorAirUnit" for the individual DOAS. The outdoor air is pre-heated at 55F. The PSZ provide 100% air economizer.
Most of the model runs fine, except that ... I get a lot of hours where the heating set-point is not met for the common spaces. I have run multiple hourly reports and I noticed that randomly, the PSZ stop providing heating when it is actually needed. I feel like this might not be a capacity issue since the "Unitary System Total Heating Rate" variable returns 0 for the hours where the heating set-point is not met and greater than 0 otherwise. What I cannot figure out is why my the PSZ stop providing heating because the systems are set to run all the time and to always be available. I have checked the heating/cooling sequence in "ZoneHVAC:EquipmentList", the DOAS are set to 1 and the PSZ to 2 so the PSZ should run...
Also, I the .err file shows the following warning "Calculated design heating load for zone= [...]is zero." for some of the common zones. This doesn't seem like it would be linked but since it happens only for the common zones, I thought that it might be important to precise it here.
According to you, what could I be missing? What should I investigate?
I have attached a excerpt of an hourly report.
Thank you in advance for your help!
Attachment not found: D:\Eudora\Attach\HourlyReport.xlsx