[Equest-users] PSZ-HP High heating unmet load hours

[Lam, Linda]

Equest Users:
 
I'm modeling a single story building with 2 packaged rooftop HP units in Las Vegas. I have allowed the program to autosize airflow and cooling and heating capacities.
 
I'm guessing that the high amount of underheated hours is due to the fact that the PSZ system type uses only one of its assigned zones as the control for constant volume airflow.  I have designated the control zone as the zone with the highest internal loads.  This works OK in cooling mode, though, I still have about 400 undercooled hours.  But in heating mode, the zone with the highest internal loads does not need as much heat as the other zones.  Since it's a constant volume system and the control zone is saying "no heat needed", the rest of the zones are not getting any heat.  Is that right??
 
Following through with the assumption above, I tried to increase the minimum cfm/sqft on zone level to 0.5, but my underheated hours went up.
I only manage to decrease unmet heating hours after I increase the cfm on the system level to about 5 times what Trane sizes. 
 
Can someone help me out here?
Thank you!!
Linda
 
 
Linda Lam, LEED® AP
WSP Flack + Kurtz
405 Howard Street, Suite 500
San Francisco, CA 94105
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