ASHRAE-90.1-2022- - Page 085
Extracted Content
- Ducts or plenums located in heated spaces, semiheated spaces, or cooled spaces .
- For runouts less than 10 ft in length to air terminals or air outlets, the rated R-value of insula- tion need not exceed R-3.5.
- Backs of air outlets and outlet plenums exposed to unconditioned space or indirectly condi- tioned space with face areas exceeding 5 ft [2] need not exceed R-2; those 5 ft [2] or smaller need not be insulated.
6.4.4.1.3 Piping Insulation. Piping shall be thermally insulated in accordance with Tables 6.8.3-1 and 6.8.3-2. Exceptions to 6.4.4.1.3:
- Factory-installed piping within HVAC equipment tested and rated in accordance with Section 6.4.1.
- Piping that conveys fluids having a design operating temperature range between 60°F and 105°F, inclusive.
- Piping that conveys fluids that have not been heated or cooled through the use of fossil fuels or electricity (such as roof and condensate drains, domestic cold-water supply, and natural-gas piping ).
- Where heat gain or heat loss will not increase energy use (such as liquid refrigerant piping ).
- In piping 1 in. or less, insulation is not required for strainers, control valves, and balancing valves.
6.4.4.1.4 Sensible Heating Panel Insulation. All thermally ineffective panel surfaces of sensible heating panels, including U-bends and headers, shall be insulated with a minimum of R-3.5. Adjacent build- ing envelope insulation counts toward this requirement.
6.4.4.1.5 Radiant Floor Heating. The bottom surfaces of floor structures incorporating radiant heating shall be insulated with a minimum of R-3.5. Adjacent building envelope insulation counts toward this requirement.
Exception to 6.4.4.1.5: See Section 5 requirements for heated slab-on-grade floors incorporating
radiant heating.
6.4.4.2 Ductwork and Plenum Leakage 6.4.4.2.1 Duct Sealing. Ductwork and all plenums with pressure class ratings shall be constructed to Seal Class A . Openings for rotating shafts shall be sealed with bushings or other devices that seal off leaking air. Pressure-sensitive tape shall not be used as the primary sealant unless it has been certified to comply with UL-181A or UL-181B by an independent testing laboratory, and the tape is used in accordance with that certification. All connections shall be sealed, including (but not limited to) spin-ins, taps, other branch connections, access doors, access panels, and duct connections to equipment . Sealing that would void product listings is not required. Spiral lock seams need not be sealed. All duct pressure class ratings shall be designated in the design documents.
6.4.4.2.2 Duct Leakage Tests. Ductwork that is designed to operate at static pressures in excess of 3 in. of water and all ductwork located outdoors shall be leak-tested according to industry-accepted test procedures (see Informative Appendix E). Representative sections totaling no less than 25% of the total installed duct area for the designated pressure class shall be tested. All sections shall be selected by the building owner or the designated representative of the building owner. Positive pressure leakage testing is acceptable for negative pressure ductwork . The maximum permitted duct leakage shall be
Lmax = CLP [0.65]
where Lmax = maximum permitted leakage, cfm per 100 ft [2] of duct surface area CL = 4, duct leakage class, cfm per 100 ft [2] of duct surface area per in. of water [0.65]
P = test pressure, which shall be equal to the design duct pressure class rating, in. of water 6.4.5 Walk-In Coolers and Walk-In Freezers. Site-assembled or site -constructed walk-in coolers and walk-in freezers shall conform to the following requirements:
a. Shall be equipped with automatic door closers that firmly close walk-in doors that have been closed to
within 1 in. of full closure. Exception to 6.4.5(a): Doors wider than 3 ft 9 in. or taller than 7 ft. b. Doorways shall have strip doors (curtains), spring-hinged doors, or other method of minimizing infiltra tion when doors are open.
ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 83