[Equest-users] Water-side Economizers NOT on Airside System?

Paul Riemer Paul.Riemer at dunhameng.com
Thu May 13 14:04:03 PDT 2010


James & Cassie,
I have been able to have chilled water loops with only process loads.  To avoid the zero design flow errors on loops, I often put in a tiny process load with a schedule that is only on for a single hour on the design day.
Admittedly, I have not tested this approach with all of the free cooling operations but I think it is worth trying before creating a dummy space and AHU.

Paul Riemer
Dunham


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of James Hansen
Sent: Thursday, May 13, 2010 3:58 PM
To: Cassie Waddell; equest-users at lists.onebuilding.org
Cc: Amit Khanna
Subject: Re: [Equest-users] Water-side Economizers NOT on Airside System?

You already know how to make it work (your last recommendation about building a dummy zone).

Build a dummy zone, include the IT room max power load (KW), create a fan coil system for that room, and just zero out the fan energy.  You'll also need to use a free-cooling chiller in your loop.

Or, you can do it all thru the chiller - the free-cooling chiller provides waterside economizer operation automatically for your chilled water loop, and you don't have to specify a system if you don't want to.  However, I've never done it this way before, and I'm not sure if a loop HAS to have a system attached, otherwise you might get no-flow errors even with a process load??  You'd have to check this...

It would be interesting to do it both ways, and compare results.

GHT Limited
James Hansen, PE, LEED AP
Senior Associate
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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Cassie Waddell
Sent: Thursday, May 13, 2010 4:47 PM
To: equest-users at lists.onebuilding.org
Cc: Amit Khanna
Subject: [Equest-users] Water-side Economizers NOT on Airside System?

We are designing an integrated water-side plant to serve cold water directly to IT racks (No air). We're projecting that at 65F water temperature, we should get more than 65% compressor-free cooling.

The current modeling approach it to build a dedicated cooling system (chiller, cooling tower, associated loops) with a direct load placed on the loop. We are having difficulty in determining whether or not we can model a water-side economizer using this approach because the water-side economizer is specified within the air system (which we have none). The issue in eQuest is how to introduce water-side economizer in a secondary loop that only serves process loads and no zones? Is the correct way to build a dummy zone and system and zero-out the fan power?

Any ideas?
________________________________
Cassie Waddell
Mechanical Engineer, LEED(r) AP
Arup
560 Mission St, Seventh Floor
San Francisco CA 94105
tel: 1 415 946 1660
fax: 1 415 957 9096
cassie.waddell at arup.com<mailto:cassie.waddell at arup.com>
www.arup.com


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