4 JOHNSON CONTROLS
Ratings
ARI CERTIFICATION PROGRAM
The performance of YORK Millennium chillers is certied
to the Air Conditioning and Refrigeration Institute (ARI)
complying with the certication sections of the latest issue
of ARI Standard 550/590. Under this Certication Pro-
gram, chillers are regularly tested in strict compliance with
this Standard. This provides an independent, third-party
verication of chiller performance.
COMPUTERIZED PERFORMANCE RATINGS
Each chiller is custom-matched to meet the individual
building load and energy requirements. A large number
of standard heat exchangers and pass arrangements are
available to provide the best possible match.
It is not practical to provide tabulated performance for
each combination, as the energy requirements at both full
and part- load vary signicantly with each heat exchanger
and pass arrangement. Computerized ratings are avail-
able through each Johnson Controls sales ofce. These
ratings can be tailored to specic job requirements, and
are part of the ARI Certication Program.
OFF-DESIGN PERFORMANCE
Since the vast majority of its operating hours are spent
at off-design conditions, a chiller should be chosen not
only to meet the full-load design, but also for its ability to
perform efciently at lower loads and lower tower water
temperatures. It is not uncommon for chillers with the
same full-load KW/TON to have an operating cost differ-
ence of over 10% due to part-load operation.
Part-load information can be easily and accurately gener-
ated by computer. And because it is so important to an
owner’s operating budget, this information is now stan-
dard within the ARI Certication Program in the form of
an Integrated Part-Load Value (IPLV), and Non-Standard
Part-Load Value (NPLV).
The IPLV / NPLV formulas from ARI Standard 550/590
closely track chiller operations, and provide a more ac-
curate indication of chiller performance than the previ-
ous IPLV / APLV formula. A more detailed analysis must
take into account actual building load proles, and local
weather data. Part-load performance data should be ob-
tained for each job using its own design criteria.
Rated in accordance with the latest
issue of ARI Standard 550/590.
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