[Equest-users] which chiller curve(s) to modify?

[Jeremy Poling]

Sounds like the same 2 curve names I received from Trane when I asked for them recently – I did a Google search and found something James Hirsch Associates prepared for California at:

 

http://www.energy.ca.gov/title24/2005standards/archive/documents/measures/20/20_2002-03_CONDENSER.PDF

 

The text that made me assume that “condenser relief” was synonymous with “condenser reset” was contained on the first page within the “Description” section.

 

Jeremy R. Poling, PE, LEED AP+BDC



 

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Diglio
Sent: Monday, March 14, 2011 10:32 AM
To: James Hansen; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] which chiller curve(s) to modify?

 

Jim:

What do you mean by condenser relief?

Paul Diglio

 

________________________________

From: James Hansen <JHANSEN at ghtltd.com>
To: equest-users at lists.onebuilding.org
Sent: Mon, March 14, 2011 11:23:04 AM
Subject: [Equest-users] which chiller curve(s) to modify?

I know there was a recent discussion about chiller curves, but I can’t seem to access www.gard.com right now, so I thought would send out this email since I don’t remember it being discussed.

 

I have two different curves for a standard water-cooled 200-ton screw chiller:

 

1)      EIR based on PLR, but with AHRI condenser relief

2)      EIR based on PLR, with NO condenser relief, and varying return chilled water temperature (from design at 100% to only about a 2 degree delta between supply and return at the 20% load range)

 

Which curves should I modify with custom curves?  I am so confused.

 

The f(PLR) curve says it should be the EIR vs PLR with no condenser water reset.  That one’s the easy one.  I already set that one up, and it’s about $1000 cheaper a year than the default curve, so I know it’s at least in the right range.

 

But the f(t evap leaving, t cond entering) says it’s a quadratic curve, but since there are two variables, shouldn’t it be bi-quadratic like the Cooling Capacity curve as a function of entering CW and leaving CHW?

 

When you all get chiller PLR curves with condenser relief, which curve(s) do you modify and to what extent?

 

Thanks!

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Cell)

703-243-1200 (Office)

703-276-1376 (Fax)

www.ghtltd.com <http://www.ghtltd.com/> 

 

 

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