[Equest-users] Table G 3.1.3.7

[Matthew Baron]

HI,
The type and number of chillers for system 7 & 8 (G3.1.3.7) states that you shall model the chillers as indicated on the table. The table shows if you have a peak building load of more than 600 tons you need to have 2 water cooled centrifugal chillers minimum with no chiller over 800 tons.(see attachments)
[G3.1.3.7.png]
[table g3.1.3.7.png]

For the kw they are simply taking the COP=Work done/Work input. So they are converting the cooling tons to kw and dividing it by the COP to obtain chiller demand.

Thanks,
Matthew J. Baron
[wendel EM]

Wendel, 140 John James Audubon Pkwy, Suite 201, Buffalo, NY 14228
p 716.688.0766   f 716.625.6825   e mbaron at wendelcompanies. com   w wendelcompanies. com

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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Rakesh Desai
Sent: Thursday, October 17, 2013 8:58 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Table G 3.1.3.7

Dear All,


1.        I had submitted energy model for certification and have received following reply:

As per table G3.1.3.7, ASHRAE 90.1.2007, "as chiller auto size capacity is more than 600 tons, centrifugal chiller should be considered".

My building conditioned area is < 22296 m2 and as per model my chiller capacity is more than 600 TR and I have to use 2 chillers. I have modeled 2 nos. screw chillers of equal capacity (auto size mode) with 5.5 COP.

I checked the table and no where it is written that we need to model centrifugal chillers.

Can someone help me to understand where I went wrong?


2.        I had submitted PS E report of all rotations of base case and have received following reply:
Peak demand (946.52kW) reported for cooling is not matching with chiller input (For 2*613 TR and 5.5 COP, 783kW). So cooling savings in not justified.

As per first submittal comment, I had changed my chiller to auto size mode and the chiller capacity is selected by model and not by me. Now, I have received above comment. What is the way out?



Thanks,

Rakesh Desai
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