ASHRAE-90.1-2022- - Page 084
Extracted Content
a. water-cooled chilled-water plants larger than 1500 tons peak cooling capacity for Climate Zones 5
through 8, 3C, and 4C, and larger than 1000 tons peak cooling capacity for all other zones; and b. air-cooled chilled-water plants larger than 860 tons peak cooling capacity for Climate Zones 5 through 8,
3C, and 4C, and larger than 570 tons peak cooling capacity for all other zones.
The efficiency shall be calculated in kW /ton (see Informative Appendix E).
6.4.3.11.2 Electric-Motor-Driven Chiller System Recording and Reporting. The electrical energy use efficiency shall be trended every 15 minutes and graphically displayed and include hourly, daily, monthly, and annual data. The system shall maintain all data collected for a minimum of 36 months.
6.4.3.12 Economizer Fault Detection and Diagnostics (FDD). Air-cooled direct-expansion cooling units listed in Tables 6.8.1-1 and 6.8.1-2, where an air economizer is installed in accordance with Section 6.5.1, shall include a fault detection and diagnostics (FDD) system complying with the following:
a. The following temperature sensors shall be permanently installed to monitor system operation:
- Outdoor air
- Supply air
- Return air, where required for economizer control b. The system shall have the capability of displaying the value of each sensor. c. The FDD system or unit controls shall be capable of and configured to provide system status by indicat ing the following:
- Free cooling available
- Economizer enabled
- Compressor enabled
- Heating enabled
- Mixed-air low-limit cycle active d. The FDD system or unit controls shall have provisions to manually initiate each operating mode so that
the operation of compressors, economizers, fans, and the heating system can be independently tested and verified. e. The FDD system shall be capable of and configured to detect the following faults:
- Air temperature sensor failure/fault
- Not economizing when the unit should be economizing
- Economizing when the unit should not be economizing
- Damper not modulating
- Excess outdoor air f. The FDD system shall be capable of and configured to report faults to a fault management application or DDC system accessible by operating or service personnel, or annunciated locally on zone thermostats .
Informative Note: ASHRAE Guideline 36 includes detailed sequences of control for monitoring and alarming air economizer faults for air economizers that are controlled by DDC systems .
6.4.4 HVAC System Construction and Insulation 6.4.4.1 Insulation 6.4.4.1.1 General. Insulation required by this section shall be installed in accordance with industryaccepted standards (see Informative Appendix E). These requirements do not apply to HVAC equipment . Insulation shall be protected from damage, including that due to sunlight, moisture, equipment maintenance and wind, but not limited to the following:
a. Insulation exposed to weather shall be suitable for outdoor service, e.g., protected by aluminum, sheet
metal, painted canvas, or plastic cover. Cellular foam insulation shall be protected as above or painted with a coating that is water retardant and provides shielding from solar radiation that can cause degradation of the material. b. Insulation covering chilled-water piping, refrigerant suction piping, or cooling ducts located outside the
conditioned space shall include a vapor retardant located outside the insulation (unless the insulation is inherently vapor retardant), all penetrations and joints of which shall be sealed.
6.4.4.1.2 Duct and Plenum Insulation. All supply and return ducts and plenums installed as part of an HVAC air distribution system shall be thermally insulated in accordance with Table 6.8.2.
Exceptions to 6.4.4.1.2:
- Factory-installed plenums, casings, or ductwork furnished as a part of HVAC equipment tested and rated in accordance with Section 6.4.1.
82 ANSI/ASHRAE/IES Standard 90.1-2022 (I-P)