In the proposed design an AHU is connected to a lot of zones. In that AHU there is a preheat coil. I have to model the baseline model as system 4 PSZ-HP. In order to meet the setpoint temperatures I think that I cannot create a PSZ-HP that is connected to so many zones, i.e. I have to create more than one PSZ-HP system. According to G3.1.2.3 “If the HVAC system in the proposed design has a preheat coil and a preheat coil can be modeled in the baseline, the baseline system shall be modeled with a preheat coil controlled in the same manner”. If I create many PSZ-HP systems in the baseline model, corresponding to an only AHU system in the proposed building, shall every PSZ-HP system have a preheat coil?
With Regards
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
October 22, 2012 - 1:17 pm
No preheat coil is required for a system 4.
Francesco Passerini
engineer90 thumbs up
October 22, 2012 - 1:36 pm
Hello, Marcus. Do you mean that for system 4 preheat coil is required even if there is no preheat coil in the proposed building? What is the reason?
In EnergyPlus I could satisfy the electric auxiliary heat with an AirLoopHVAC:UnitaryHeatPump:AirToAir in which the electric coil is after the DX heating coil. It is illustrated at p.995 of the manual: http://apps1.eere.energy.gov/buildings/energyplus/pdfs/inputoutputrefere...
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
October 24, 2012 - 12:16 pm
You do not model a preheat coil for a system 4 in the baseline despite G3.1.2.3. The preheat coil would be electric resistance and the resistance coil cannot operate above 40 degrees so there is a potential conflict in modeling a preheat coil for a system 4.