[EnergyPlus_Support] Air handling unit with economiser

["careym.cosmaj" <mc@xxxxxxxxxxxx>]

Hi,

Trying to cobble together a "simple" model with an air handler, mixing
box (recirculation and outdoor air), chilled water cooling coil,
heating water heating coil, and constant air volume fan complete with
an economiser on the outdoor air supply serving a single zone.

Have attempted;

1. To take a VAV system (COMPACT HVAC:SYSTEM:VAV), we can disable the
reheat coil and make the system serve a single zone however the model
varies air flow rate which is by nature what a VAV system does and not
what we are after.

2. To take a COMPACT HVAC:ZONE:FAN COIL and add economiser control to
the mixing box but all we end up with a model which heats and cools
without economiser and warnings about orphan objects

** Warning ** The following lines are "Orphan Objects".  These objects
are in the idf
**   ~~~   **  file but are never obtained by the simulation and
therefore are NOT used.
**   ~~~   **  See InputOutputReference document for more details.
************* Object=OUTSIDE AIR SYSTEM=FCU OA SYSTEM
**   ~~~   ** Object=CONTROLLER LIST=FCU OA SYSTEM CONTROLLER
**   ~~~   ** Object=AIR LOOP EQUIPMENT LIST=FCU OA SYSTEM EQUIPMENT
**   ~~~   ** Object=CONTROLLER:OUTSIDE AIR=FCU OA CONTROLLER

and no idea what we are missing from the file to get the outdoor air
controller to do its thing.

3. To take COMPACT HVAC:SYSTEM:UNITARY have e+ expand the model, which
results in a FURNACE:HEATCOOL and then switch the
COIL:DX:CoolingBypassFactorEmpirical for a COIL:Water:Cooling and the
COIL:GAS:HEATING for a COIL:Water:SimpleHeating (this is suggested
elsewhere in the yahoo group).  Unfortunately e+ will not permit a
COIL:Water:Cooling and COIL:Water:SimpleHeating in a FURNACE:HEATCOOL
object.


What is the recommended way of achieving such an air handling system,
construct our own air handler from basic objects? Which seems to be
what the example file SmOffPSZ.idf ends up doing.

Should we be expanding the COMPACT HVAC:SYSTEM:VAV and replacing the
variable speed fan with a constant speed fan?

Any suggestions?

Thank you.

Regards,

Mark Carey


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