[Bldg-sim] eQuest - FCU - how to make it cycle

Aulbach, John jaulbach at nexant.com
Wed Sep 24 11:44:21 PDT 2008


I believe a cycling type of fan shuts off when the space temperature falls below the Throttling Range you assign for the particular mode (Heating or Cooling) you are in. For example, a cooling thermostat of 72°F and a throttling range of 4°F yields a high limit of 74°F and a low limit of 70°F.  When you fall within this range, I believe the fan should shut off (if you choose the Fan Intermittent mode).There should be no airflow.
 
But now I am unsure if ALL SYSTEMS allow fan cycling..I believe you can with a fan coil.
 
The other responder is correct in that eQuest deals in hourly chunks, and a fan may only be on part of an hour, thus a lower CFM, but in reality, the same CFM for only part of the hour.
 
John R. Aulbach, PE, CEM
Project Manager
Nexant, Inc.
701 West Kimberly Ave., Suite 245
Placentia, CA 92870-6342 USA
Phone: 714-524-4402
Fax: 714-524-4407
email: jaulbach at nexant.com
 
 
 
 
 

________________________________

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Yuvaraj Saravanan
Sent: Wednesday, September 24, 2008 10:57 AM
To: equest-users-bounces at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] eQuest - FCU - how to make it cycle



Hi All, 
Does anyone know how to make a FCU cycle ON/OFF based on the zone thermostat setting? I tried choosing the "Fan on mode" to be intermittent in the Fan->Flow parameters tab. When I make the fan to be intermittent, fan is cycling but the supply CFM is no more a constant volume. It is varying the supply CFM. I observed this in the hourly report.

ASHRAE standard 90.1 requires the fan to cycle to meet the loads during unoccupied hours. How everybody model this in eQuest when you have a FCU system?

Any suggestions is greatly appreciated. 

Regards, 
Yuvaraj 
______________________________________________ 
Yuvaraj Saravanan, PE 
Engineer 

Arup 
12777 West Jefferson Boulevard Suite 200 
Los Angeles CA 90066 
tel:    1 310 578 4400 
dir:    1 310 578 4521 
fax:    1 310 577 7011 
internal freecall: x20521 
yuvaraj.saravanan at arup.com
www.arup.com <file://www.arup.com>  


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