Baseline has space heat, but proposed has zero space heat

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Dear All,

I have a model located in Mexico. The baseline is equipped with PSZ+Heat
pump and proposed is equipped with VFD + Heat pump. For some reasons, the
baseline has a normal space heat, but the proposed shows 0 space heat. The
envelop, schedule, setpoints, outside air flow rates are all the same.
1. What could be the possible reason for something like this?
2. Does anyone know how eQuest calculate the heating/cooling capacity at
the system and zone level? For example, I set up the cooling and heating
capacity for the system and set up setpoints for each zone. So in the SV-A,
it only shows the heating/cooling capacity of the system, and for each zone
will be zero heating and cooling capacity?
3. What is the extraction rate (KBTU/HR) and addition rate(KBTU/HR) in
SV-A? Where are they from?

[image: image.png]

[image: image.png]

Thank you!

Jing Hong's picture
Joined: 2011-09-30
Reputation: 0


Some ideas:
1-see other email on System Heating Temperatures.
2-The Capacities are based on the Heating & Cooling Degree (HDD/CDD) days (if entered) or from the weather file if no HDD/CDD is specified (I believe). The System Sizing, Cooling Sizing Ratio, and Heating Sizing Ratio are all used, if entered. They default to 1.0 if no capacities are entered, or grey out if capacities are entered. The sizing calculations are the first ~20% of the eQuest simulation. On SV-A the Heating and Cooling Capacities will be shown at the top. The Zone Heating Capacities should show up on a zone by zone basis in the table below. Right now shown as ?0.0?, most likely due to issue(s) from other email.
3-These can be confusing. The Cooling Capacity is a function of if there is a zoing cooling coil (theres not in a VAV system) The Extraction Rate is the calculation to determine what the maximum heat which can be extracted from the zone, based on the airflow and temperature difference of the Design-Cool-T and the Min-Supply-T. The Heating Capacity is the capacity of the zone heating coil (reheat coil in a VAV case) and is the 1.08*CFM*Reheat_deltaT*Supply Ratio. The Addition Rate is similar, though it is 1.08*CFM*(Max-Supply-T - Design Heat-T)*Supply Ratio.

Mechanical Engineer, Energy Analyst

Henderson Engineers
daric.adair at

Licensed in KS

Daric Adair's picture
Joined: 2017-10-21
Reputation: 0