Hours outside of throttling range -VAV system

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I likewise have been having enormous trouble reducing the hours outside of
the throttling range for my design case building. In the winter months in
the morning I will have multiple hours outside of the throttling range for
multiple zones and this exceeds 300 hours.

Things I have varied but did not solve the problem include:

1. Occupancy schedule
2. Heating Design Day Schedule
3. Night Setback Temperature
4. Boiler Size
5. Loop Capacity
6. Pump Size
7. Delta T for heating and Pre-heating coils
8. Minimum Outside Air
9. Throttling Range
10. Design temperature

At this point I am randomly changing settings to reduce the amount of hours
outside of throttle range, but I would like to have a more deductive
process.

I have a suspicion that there was a setting in the wizard that is overriding
my inputs, but that is conjecture.

My engineer designed the system in Trane Trace and oversized it by 25% so
the designed heating equipment should be adequate.

Thank you,

James F. Geers

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Go to: Air-side HVAC System Parameters -> Fans -> Night Cycle Control -> Select: Cycle on any.

Timothy Howe, MS, LEED(r) AP

Howe, Timothy's picture
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Using "Cycle on Any" does the trick. Thank you. Will this affect my DCV?

James F. Geers

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Turning "cycle on any" on will allow the system to cycle on at night or
whenever the fan schedule is set to "0". This will usually get rid of the
hours that are out of range when the system starts up.

Steve Mignogna's picture
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