[Equest-users] Written explanation of the System Sizing Logic as shown on the SYSTEM Tab

[John Aulbach]

My boss is a skeptic of the data presented in the System Sizing Tab that can be generated when you are the System screen and hit the Summary tab, and I don't have a good explanation.  We looked at a single office floor in the Southern California are, a floor with about 50% glass and about 29,000 sf. The System tab generated a size of 107 tons (installed tonnage for the floor was 80 tons). Most load information was defaulted.

The installed tonnage was 80 tons and the unmet hours were few.


When we increased the airflow slightly, the load size was 80 tons.  When we increased the total supply airflow double, the tonnage went to about 140 tons.

And, of course, the unmet hours varied, inconsistent of course between SS-R and SS-F and the System Sizing tab.

All I am looking for is a detailed explanation of how the system sizing tab is generated. Obviously, this is not TRACE sizing routine, but there are some of us who must use this table to have a sense if a builidng has enough cooling after equipment (read-SERVERS) has been added to a floor.

Can anyone who had had time to research this care to share their finds?

Thanks.

John Aulbach.


What is 



________________________________
From: Jun Furuta <JFuruta at energy-solution.com>
To: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
Sent: Tuesday, September 20, 2011 1:39 PM
Subject: [Equest-users] Modeling 2 stage cooling in a single zone packaged unit


Hello,
 
I would like to model a packaged single zone AC with gas furnace that has two stage cooling with using two compressors. The system has an integrated  economizer and a constant speed fan.
 
Is there a way to indicate two compressors in the PSZ system type or am I supposed to use the PVVT system, despite being a single zone system and not having neither a variable speed compressor or fan? And if the PVVT system type is to be used, any advice on configuring the system would be greatly appreciated.
 
Thanks,
 
-Jun
 
 
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