[Equest-users] IPLV in Heat Pumps

Carolyn Balant CBalant at mcw.com
Tue Dec 22 11:53:36 PST 2009


A colleague of mine has an answer about this below.

Regards,

Carolyn Balant P.Eng., LEED AP
Senior Energy Engineer

MCW Custom Energy Solutions Ltd. <http://www.mcw.com>
156 Front Street West Suite 600
Toronto, ON M5J 2L6
Phone 416-598-2920 ext.315
Fax 416-598-5394

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Carolyn:

Short answer:
Amadeep should use SEER for his project.  IPLV is used for chillers, but it is no better than SEER.  I believe EER and SEER include fan power, but I am not positive.  I know that IPLV does not include power for any peripherals.

Long answer:
EER (BTUH/watt) and COP (dimensionless) are rated at full load.
SEER (seasonal efficiency ratio) and IPLV are supposedly based on an entire "average" season of operation in a "typical" system, with a large number of assumptions about load profiles, outdoor temperature profiles, presence or absence of economizer cycles, and operating profiles.  SEER is in BTUH/Watt, and IPLV is either in kW/ton or expressed as COP (dimensionless).  The "V" stands for Value because, incredibly, the units of IPLV are ambiguous!

IPLV is generally used for chillers. It is based on:
1% of time at     100% load
42% of time at   75% load
45% of time at   50% load
12% of time at   25% load,
with different assumed condenser water temperatures at the various loads.

(There are published formulae for calculating IPLV with any arbitrary load profile. Unfortunately, and likely because of the ambiguity of the units, the authors used the COP form of the formula for kW/ton, and vice versa.  Because COP and kW/ton are essentially reciprocals of each other, the formulae don't work.  But that's another story.)

SEER is another ARI standard, presumably based on a similar load profile.  I don't know what the profile looks like, because ARI charges $45 for a peek at the standard.  And guess what...

Regards,

Jamie


Jamie Smith P.Eng
Mechanical Engineer

MCW Consultants Ltd. <http://www.mcw.com>
156 Front Street West Suite 600
Toronto, ON M5J 2L6
Phone 416-598-2920 ext.264
Fax 416-598-5394

This e-mail may be privileged and confidential. Any unauthorized use is strictly prohibited. If you received this e-mail in error, please contact the sender directly.

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________________________________
From: Paul Diglio [mailto:paul.diglio at sbcglobal.net]
Sent: Monday, December 21, 2009 5:15 AM
To: Amandeep Singh; equest-users at lists.onebuilding.org; John Aulbach
Subject: Re: [Equest-users] IPLV in Heat Pumps

Amandeep:

I agree with John.  Actually, I believe IPLV is a somewhat new rating that applies to larger systems.  EER or COP are much more accurate ratings.

I am confused about the SEER and IPLV ratings.  What temperature bin do they use to calculate these numbers?  It would seem to me that an AC system in the south would operate at a higher load throughout the cooling season than one in the northeast.  Of course, it would depend on how the system was sized.  An oversized system will operate at a much lower load ratio than a tightly sized system.

Does anyone know the formula?

Paul Diglio, CEM

--- On Sun, 12/20/09, John Aulbach <jra_sac at yahoo.com> wrote:

From: John Aulbach <jra_sac at yahoo.com>
Subject: Re: [Equest-users] IPLV in Heat Pumps
To: "Amandeep Singh" <amandeep.singh at energycenter.org>, equest-users at lists.onebuilding.org
Date: Sunday, December 20, 2009, 9:02 PM
Amandeeph:

As far as I am concerned, IPLV is a mythical number, like SEER. It is based on assumed levels of usage for a pumed annual usage. If your truly need part load curves, ask the manufacturer for the 75%, 50% and 25% points. You cannot evolve these four numbers out of a single mnumber (IPLV).

________________________________
From: Amandeep Singh <amandeep.singh at energycenter.org>
To: equest-users at lists.onebuilding.org
Sent: Thu, December 17, 2009 1:03:45 PM
Subject: [Equest-users] IPLV in Heat Pumps
Hello everyone,

I was working on a school model located in Lakeside,  San Diego county. The school has Bard wall mount heat pumps (capacity - 2 to 4 tons), really old one. I got manufacture data of the old and new units for replacement. The new units data has EER, IPLV and COP ratings. I  would prefer to use IPLV instead of EER rating in case of cooling  to calculate savings.  The eQuest does have options for EER and SEER but not for IPLV in the schematic design wizard.  What should I do here?

Does it make sense to use IPLV instead of EER to calculate savings for the Lakeside?

Thanks,
Aman


[cid:image001.jpg at 01CA8313.E37BD040]

Amandeep Singh
Energy Engineer
8690 Balboa Ave, Suite 100
San Diego, CA 92123-1502
858.634.4729 phone
858.244.1178 fax
www.energycenter.org<http://www.energycenter.org/> web


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