Re: [EnergyPlus_Support] Compact HVAC problems

[Fred Buhl <wfbuhl@xxxxxxx>]

Josh,

In COMPACT HVAC:ZONE:VAV, try setting Zone Damper Heating Action to
Reverse Action.

fred Buhl

josh_miarch wrote:
> I'm working on a one-zone model that is conditioned using the COMPACT
> HVAC VAV objects. I'm having problems controlling the supply air flow. 
>
> I did a run to determine the maximum zone air flow, divided my minimum
> required OA flowrate by this number, and then set the result (0.0976)
> as the Zone Supply Air Min Flow Fraction in the COMPACT HVAC:ZONE:VAV
> object.
>
> The problem I'm having is that the simulation, when heating, fixes the
> supply air flowrate to the zone at its minimum, even when there is a
> substantial heating load on the zone. As a result, the zone
> temperature is often well below (~4°C) its heating setpoint when the
> VAV system is running in the heating season. Changing the Zone Supply
> Air Min Flow Fraction to a higher value (ie 0.3) fixes this problem in
> that it raises the minimum flowrate to an extent that the zone
> setpoint can be met, but the system still appears to fix the supply
> air flowrate at its minimum.
>
> I'm wondering if anyone can tell me why this system doesn't vary its
> supply air flow rate as a VAV system presumably should, or if I'm
> understanding something incorrectly. I will shortly upload the model
> if anyone would like to take a look
> at them.
>
> Many thanks,
>
> Josh
>
>
>
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