[Equest-users] eQUEST - serios trouble with LEED review

[Bishop, Bill]

Heinrich,
 
The chiller pumps requirement your reviewer is referring to is in
Section G3.1.3.11 (not G3.1.11). The model you sent currently has one
primary CHW pump attached to each of your two chillers, a separate
primary CHW pump on the primary loop, one secondary CHW pump and one
condenser water pump. You labeled your primary chiller pumps "Secondary
Pump CHW 1" and "Secondary Pump CHW 2", which is probably why the
reviewer thinks you only have one primary pump (the one on the primary
CHW loop labeled "Primary CHW Pump"). I suggest making the following
changes:
*	Delete the separate pump attached to the primary CHW loop
*	Relabel the chiller pumps to indicate they are primary loop
pumps
*	Add condenser water pumps for each chiller through the "Loop
Attachments" tab of the chillers; delete the other CW pump.
*	Change both the primary loop and secondary loop sizing option to
"secondary" to allow eQUEST to size based on coil loads.
*	Change the chiller capacity ratio for each chiller to 0.50. (Or
use 0.575 if you want to oversize by 15% per G3.1.2.2 - I don't know if
this is supposed to apply to chillers.) Each chiller will be sized for
half the total load.
*	Allow the chiller capacity to default (remove the 0.9 MBtu/h).
*	Make sure you include both/all pages of the PS-C report - your
reviewer will then see that the secondary CHW pump is variable flow.
(Your zones have two-way valves already.)
*	The PV-A report will show that the total primary CHW pump flow
will nearly match the secondary CHW pump flow.
 
Regards,
Bill
 
William Bishop, PE, BEMP, LEED(r) AP | Pathfinder Engineers & Architects
LLP
Mechanical Engineer
 
 134 South Fitzhugh Street                 Rochester, NY 14608
T: (585) 325-6004 Ext. 114            F: (585) 325-6005
wbishop at pathfinder-ea.com           www.pathfinder-ea.com
<http://www.pathfinder-ea.com/> 
P   Sustainability - the forest AND the trees. P 
________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of
Heinrich.ib-bauklima.de
Sent: Monday, January 24, 2011 12:28 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] eQUEST - serios trouble with LEED review
 
Hi Everyone,
 
I got a review comment that got me in big trouble and I can't find the
solution yet.
May be there is no solution for this in eQUEST....!
I rate this forum as the very best address for difficulties with eQUEST
and LEED EAc1 simulation.
So please give me some guidance and feel free to testthe model attached.
 
Hereare the two comments of the reviewer.
"It appears as if the pumps and circulation loops were not modeled
correctly for the Baseline Case. It appears based on the PS-C reports
that there is only one primary chilled water pump and one condenser
water pump for the Baseline Case. However, ASHRAE 90.1 Section G3.1.11
requires that each chiller be modeled with separate condenser water and
chilled water pumps interlocked to operate with each associated chiller.
Please model two primary chilled water pumps and two primary condenser
water pumps in accordance with Section G3.1.11. Also update the chilled
water valves to two-way valves so that the secondary chilled water loop
operates as a variable flow loop with pumps riding the curve. Provide
updated PS-C reports confirming that the changes have been made."
"It is unclear why the pump flow for the secondary chilled water loop is
so much larger than that of the primary chilled water loop when the
temperature differential for both loops is expected to be the same. It
also appears based on the outputs in PS-C that the secondary chilled
water loop is operated at the same load for every hour that it is on
even though it is a variable speed pump. Please update the secondary
chilled water loop flow to be consistent with the primary chilled water
loop flow, and confirm that the secondary chilled water loop is
operating as a variable flow loop."
 
I have to say:
I didn't see any equest-model modeled with separate condenser water and
chilled water pumps interlocked to operate with each associated chiller.

I manually resized the boilers and chillers with reference to SS-D
report, because auto sizing of eQUEST generated capacities that were
double the size of SS-D report. Resizing of the volume flow of secondary
loop of chillers according to primary loop of chillers generated
warningmessages but changed nothing.
 
Heinrich
 
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