Unmet Load Hours and Baseline Outside Air (Jason Boehning)

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I have done several Trace runs with VRV and have seen a lot of unmet
load hours. Following are some suggestions:
1. Download the latest update from CDS. I believe they have corrected
some issues regarding unmet load hours.
2. Check your T'stat location, it should be "Room".
3. Tighten up your set back temperatures on the thermostat template. I
don't know if you are but I never use a T'stat schedule. Use the set
back temperatures and Cycle with Occupancy on the fans screen.
4. Check for very low airflows in janitors closets, storage rooms etc.
These spaces with low cooling loads may not have enough air flow to
heat. I sometimes add a minimum airflow using AC/H for these spaces.
5. IT rooms, try "No Fan Cycling" and/or no set back for these spaces.
6. Have you tried a morning warm-up schedule.
7. Make sure you use a ventilation schedule to close OA at night.
8. Last resort, increase capacity on the System's Coil's tab.

Outdoor Air,

Fans available is OK as long as you select cycle with occupancy. I would
use a fan schedule for room exhaust and optional vent fans. Schedule OA
off at night. Schedules need to be the same for baseline and proposed.

Hope this helps

Bvogt's picture
Joined: 2010-10-05
Reputation: 1