| OFF-THE-CHARTS
(OTC) COMPLIANCE DETAILS AS RELATED TO ICC CODE, AHRI, AND ACCA MANUAL S |
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THIS INFORMATION IS
INTENDED FOR INFORMATIONAL PURPOSES ONLY, TO ASSIST THE USER OF THIS
PRODUCT IN DETERMINING WHETHER IT IS COMPLIANT WITH THE REGULATIONS OF THE
JURISDICTION IN WHICH THEY INTEND TO USE IT. |
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(Software author comments
in bold italic print) |
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| I |
INTERNATIONAL MECHANICAL CODE 2009 |
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| A. |
In section M1401.3 Sizing:
"Heating and cooling equipment
shall be sized in accordance with ACCA Manual S based on building loads
calculated in accordance with ACCA Manual J or other approved
heating and cooling calculation methodologies."
The approval is by the code enforcement
official, as in all other referenced "approved's" in the code. |
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| II |
AHRI SEER Standard 210-240
- PERFORMANCE RATING OF UNITARY AIR-CONDITIONING AND AIR-SOURCE HEAT PUMP
EQUIPMENT |
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| A. |
Section 6.5, Tolerances,
reads: "To comply with this standard, measured test results shall not
be less than 95% of Published Ratings for performance ratios and
capacities." OTC average results, therefore, are
twice as accurate as the very ratings from which the manufacturer expanded
data is created from. |
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| III |
ACCA MANUAL S (2014 RELEASE) |
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| A. |
We fully realize that OTC
is NOT an officially ACCA "approved" product, and has not been
deemed "ACCA manual S compliant". |
| B. |
Section 2-5 states that
"Equipment selection and sizing requires values for total and latent
cooling capacity for the equipment operating conditions caused by the
summer design conditions for outdoor air and indoor air; and when
applicable, the effect of return duct loads, and/or engineered ventilation
loads." OTC takes these values into
consideration, which are generated by manufacturer formulas, which the
user may then compare the resulting accuracy against. |
| C. |
Appendix 13 States in the
first sentence that "The manufacturer's expanded performance data for
a particular make, model and size may be approximated by a set of linear
equations. Converting a data table to a set of equations has certain uses
and advantages. Accuracy, as it relates to the OEM's data set may be good,
but not perfect." OTC
allows for the comparison to published data and making the small
correction of error if desired. |
| D. |
Appendix 13 Section 1, use
#4 states that "The model may be used for final equipment selection
and sizing if the accuracy of the calculation engine is acceptable." OTC
is accurate to less than a standard deviation average error of 2.01%,
which can then be corrected further if desired. |
| E. |
Appendix 13 Section 1, use
#5 states that "An accurate model may be used by a code official to
verify final equipment selection and sizing". This
has always been the jurisdiction of the state building officials. |
| F. |
Appendix 13 Section 1, use
#7 states that "A model that has 1% to 10% error (typically 5% or
less) over a comprehensive range of operating conditions may be used for
preliminary design work." OTC would hope that a
building official would use the same 5% criteria to which AHRI is held for
SEER determination, in the design capacity calculation as well. |
| G. |
Appendix 13, Section 16:
Accuracy of Expanded Data: "Models attempt to duplicate OEM data
whether it is correct, or not..", "When this is not the case,
compare the questionable data with data for similar makes/models of the
same size..", " So, the questionable data was discarded, and
replaced with data that is consistent with expected tendencies. Discussing
data accuracy with an OEM is not a simple matter." OTC
realized this early on in discussions as well, and a statistical outlier
factor for questionable data was determined in our sampling data set. This
number is the basis of the maximum number we allow for results adjustment
in our product. IF YOU HAVE MANUFACTURER DATA BEYOND OUR ADJUSTMENT, YOU
SHOULD HEED ACCA'S ADVICE, AND CONTACT THE MANUFACTURER. |
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NOTE: OTC CALCULATION
ERRORS IN 11% OF 3090 SAMPLE POINTS FROM RANDOM MANUFACTURER PRODUCT DATA,
2009-2015, EXCEEDED 5%, 2.4% EXCEEDED 7%, AND 0.2 % EXCEEDED 10%. ONLY ONE
SAMPLE POINT EXCEEDED 11% ERROR. Average
sheet error from published random expanded data is currently 2.313%. The
statistical standard deviation between errors is 1.942%. |
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THE OTC SHEET IS FOR USE
WITH 0.5 THROUGH 7.5 TON AIR-COOLED RESIDENTIAL TYPE SPLIT SYSTEMS, BOTH
SINGLE AND TWO STAGE TYPES. SOME RESULTS WITH HIGH ERROR COULD OCCUR IF A
SPECIFIC BRAND HAS QUESTIONABLE EXPANDED DATA (OUTLIERS). DO NOT USE THIS
SHEET FOR TRUE VARIABLE SPEED (FREQUENCY-DRIVE) COMPRESSOR SYSTEMS EXCEPT
FOR MAXIMUM SPEED RATING. |
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OTC has not been tested with water cooled systems, results
may vary. |
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OFF-THE-CHARTS, COPYRIGHT 2012, KR SERVICES, STATE OF
LOUISIANA |
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Spreadsheet Copyright 2012
by KR Services, State of Louisiana |
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(Ver. 16.80.32
and 16.80.64) |
KR-Services-com LLC