FCU with Energy Recovery Ventilators (ERV)

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The system is a residential building with 10 FCU (cooling only) with CAV
fans. The 10 FCUs get fresh air from a dedicated (100% OA) Energy Recovery
Vent. System. The ERV system has an enthalpy wheel, a SF fan, a EF fan and a
cooling coil. All cooling is from a campus loop.

Now, we have two options to model this.

Option 1 -To model the FCUs (as they are) and then define a separate Single
Zone system with an ERV. This SZ system will not be attached to any zone but
will have an enthalpy wheel, a SF fan, a EF fan and a cooling coil. Next we
link the OA for the FCUs as "from" this Single Zone ERV system. This way we
can account for the SF, EF, Wheel Motor and CC energy at the ERV. This does
not work as eQ does not allow us to have a Single Zone system with an ERV
which is not connected to any zone.

Option 2 - Here, we are modeling the FCUs as Single Zone system with an
ERV. Thus I have a 10 Single Zone ERV systems and no FCU. Now, in the ERV
tab of the SZ ERV I can account for the air through ERV, SF kw, EF kw, wheel
motor but no CC energy. Also, we are prorating the total ERV energy based on
CFM for each FCU. The issue is that we are not able to program in the
cooling coil energy of the original ERV.

Currently, we are using Option 2 but would have preferred Option 1 as it is
closer to reality. Any thoughts?


Abhinav Devra

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Joined: 2011-09-30
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