Hey All,
I am running a load with many zones on 5 floors totaling over 300 zones. There are some zones with many unmet hours, some of the core, some perimeter. I went in and changed the sizing ratio of these zone to reduce the unmet heating hours. I am modeling this building with 9 AHU's, all VAV w/ reheat. Does anyone have any insight or suggestions on why or how these unmet hrs. exist. I have changed the hot water loop flow GPM but it had no effect on the unmet heating hrs. so I deduced this is not the cause.
Janne Kairento, E.I.T., LEED AP
Check for reverse acting thermostat, or make sure that your min-air flow
for heating is sufficient.
-rohini
Janne,
Without information on HW loop temp, cooling system type and control,
and heating control, it's tough to figure out what is going on with your
model. That being said, I will provide what help I can. The sizing
ratios on the coils only increase the coil size and do not increase
airflow which is generally why zones will have hours out of range.
Check the minimum flow ratio and airflow to your zones and make sure
they are appropriate for the loads in the space. With regards to your
system setup, make sure your reheat setpoints and supply air setpoints
are consistent.
For future reference, if you provide the input file, myself or others on
the list serve will be able to better respond to future questions.
Sam Mason
Also, make sure the throttling range is 4-6 not whatever it defaults
too. There is a writeup in online help talking about why you should do so.
Carol