[Bldg-sim] How much fan power included in EER / SEER ratings?

[Eric Studer]

Thanks for the link, James.  

I still have never seen a reliable method of converting a code-listed
unitary performance value to condensing section EIR.  

Based on my past work evaluating installed energy efficiency measures where
savings were based on installing high efficiency custom built RTUs rather
than code-compliant unitary RTUs, most savings arise from reduced internal
pressure drops and improved fan efficiencies.  The downfall of the analyses
that I reviewed, if you are wondering, is an approach that can be summarized
as follows:
  Annual ton-hrs * 12 ÷ (Base Avg Unitary EER - Proposed Avg Unitary EER)

It seems that many off-the-shelf RTUs have fan efficiencies that hover
around 55% while custom units have fan efficiencies that are around 65%.
Custom units tend to have larger coils with lower pressure drops.

Simply knowing the external static pressure during standard testing
conditions is not going to get you to a performance value for the condensing
unit if you do not also know the specific internal pressure drops or fan
efficiency.

What to assume for the generic code case fan power?  For what it is worth,
my rule of thumb is to knock ~0.20 kW/ton off the unitary EER rating.

Eric

Ph:   (781) 431-1100 ext 12
Fax:  (781) 431-1109
 
-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James V. Dirkes
II, PE
Sent: Wednesday, November 04, 2009 8:52 PM
To: 'RobertWichert'; 'Crockett, Jim'
Cc: 'BLDG-SIM'
Subject: Re: [Bldg-sim] How much fan power included in EER / SEER ratings?

The Standard is available on the AHRI Web site at
http://ari.org/Content/FindaStandard_218.aspx?Listing_PK=143

All fan energy must be included and that is calculated using a minimum
external static pressure that varies with capacity (See Table 5)


The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
 

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of RobertWichert
Sent: Wednesday, November 04, 2009 8:14 PM
To: Crockett, Jim
Cc: BLDG-SIM
Subject: Re: [Bldg-sim] How much fan power included in EER / SEER ratings?

Actually I wold expect the ARI testing to be done with 0.5" of static,
which is normally the "rated" static anyway.

I don't see any need to call this "significantly underestimating" the
energy use.  If you design to 0.5" of static, you're good to go.



-- 
Robert P. Wichert, P.Eng.
+1 916 966 9060
FAX +1 916 966 9068




================================================



Crockett, Jim wrote:

>My understanding (from very unofficial sources found while googling) is
>that when units are tested per ARI 210/240 (or 340/360), they are tested
>with a clean filter and minimal ductwork (total static of around 0.3").
>Thus, you would need to back this minimal amount of energy from the EER,
>and then add the actual fan energy.
>
>If you simply use the rated EER with no adjustment, and set your supply
>fan energy to zero, (as was recommended in the archives), then you will
>significantly underestimate your fan energy.
>
>So, is anyone familiar with the ARI 210/240 or 340/360 tests, and know
>how much fan energy is included in these tests?  Also, is the included
>fan energy different for packaged units vs. split systems?
>
>Thanks,
>
>
>
>Jim
>
>
>
>
>-----Original Message-----
>From: RobertWichert [mailto:robert at wichert.org] 
>Sent: Wednesday, November 04, 2009 8:54 AM
>To: Crockett, Jim; BLDG-SIM
>Subject: Re: [Bldg-sim] How much fan power included in EER / SEER
>ratings?
>
>Here is my favorite, from the archives.
>
>http://lists.onebuilding.org/htdig.cgi/bldg-sim-onebuilding.org/2007-Oct
>ober/005987.html
>
>
>
>
>Crockett, Jim wrote:
>
>  
>
>>How much fan power is included in the EER / SEER ratings for packaged 
>>systems, and split systems? I want to make sure I'm not 
>>double-counting fan energy.
>>
>>Thanks,
>>
>>Jim Crockett, P.E.
>>
>>Senior Project Engineer
>>
>>Energy & Carbon Management
>>
>>Nexant, Inc.
>>
>>4021 S. 700 E., Suite 250
>>
>>Salt Lake City, Utah 84107
>>
>>(801) 639-5603 - phone
>>
>>(801) 266-4786 - fax
>>
>>-----------------------------------------------------------------------
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>  
>



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