Re: [EnergyPlus_Support] Unmet load hours due to increased fan pressure rise

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Subject: Re: [EnergyPlus_Support] Unmet load hours due to increased fan pressure rise

From: jeannieboef <jeannieboef@xxxxxxxxx>

Date: Thu, 17 Jan 2013 14:31:09 +0100

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Fan Pressure should have zero bearing on unmet loads. Its only function is to calculate electricity consumption. even though the motor heat will enter the airstream if it is designated as being in the airstream, I doubt this is your problem.

That being said, your method for baseline fan power sizing by adjustment of the pressure rise looks right.

You are allowed 300 hours unmet load, as long as the design case also has 250 or more but less than 300 (deviation of 50), though proper setpoint management should keep you under 50 for a good model.

Sent from my iPhone

On 17.01.2013, at 10:15, "JFCS" <jamo0312see@xxxxxxxxx> wrote:

My model gains unmet load hours or time set point not met during cooling operations, when even i increased fan pressure rise of my fans.

First I autosized a working model with complete hvac system for my Baseline case as per "G3.1.2.8 Design Airflow Rates". Then I need to adjust my VAV's fan power as "G3.1.2.9 System Fan Power" therefore I need to increase the pressure rise of my fans. Thought i got the correct fan power but the unmet load hours is below 300hours...

Any suggestions?

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