ASHRAE-90.1-2022- - Page 081
Extracted Content
Table 6.4.3.4.3 Maximum Damper Leakage [a,b] , cfm per ft [2] at 1.0 in. of water
| Climate Zone | Outdoor Air Intake | Col3 | Exhaust/Relief | Col5 |
|---|---|---|---|---|
| Climate Zone | Nonmotorized a | Motorized | Nonmotorized c | Motorized |
0, 1, 2
Any height 20 4 20 4
3
Any height 20 10 20 10
4, 5B, 5C
| Fewer than three stories | 20 d | 10 | 20 | 10 |
|---|---|---|---|---|
| Three or more_stories_ | 20 d | 10 | 20 d | 10 |
| 5A, 6, 7, 8 | Col2 | Col3 | Col4 | Col5 |
|---|---|---|---|---|
| Fewer than three stories | 20 d | 4 | 20 | 4 |
| Three or more_stories_ | 20 d | 4 | 20 d | 4 |
a. When tested in accordance with AMCA Standard 500-D. b. Dampers smaller than 12 in. in height, width, or diameter need not be tested but shall be of the same design and construction as the smallest tested damper
meeting the listed leakage rate requirement. c. Nonmotorized dampers smaller than 24 in. in height, width, or diameter may have a leakage rate of 40 cfm/ft [2] . d. Where allowed by Section 6.4.3.4.2, Exception 2.
6.4.3.4.5 Parking Garage Ventilation Systems. Parking garage ventilation systems shall meet all of the following:
a. Separate ventilation systems and control systems shall be provided for each parking garage section . b. Control systems for each parking garage section shall automatically detect and control contaminant lev els and shall be capable of and configured to reduce airflow to 20% or less of design capacity . c. The ventilation system for each parking garage section shall have controls and devices that result in fan
motor demand of no more than 30% of design wattage at 50% of the design airflow.
Exception to 6.4.3.4.5: Garage ventilation systems serving a single parking garage section having a
total ventilation system motor nameplate horsepower not exceeding 5 hp at fan system design con- ditions and where the parking garage section has no mechanical cooling or mechanical heating .
6.4.3.5 Heat-Pump Auxiliary Heat Control. Heat pumps equipped with internal electric resistance heaters shall have controls that prevent supplemental heater operation when the heating load can be met by the heat pump alone during both steady-state operation and setback recovery. Supplemental heater operation is permitted during outdoor coil defrost cycles.
Exception to 6.4.3.5: Heat pumps whose minimum efficiency is regulated by NAECA and whose rat ings meet the requirements shown in Table 6.8.1-2 and include all usage of internal electric resis- tance heating. 6.4.3.6 Humidification and Dehumidification Control 6.4.3.6.1 Dehumidification. Humidistatic controls shall not use mechanical cooling to reduce the humidity below the lower of a dew point of 55°F or relative humidity of 60% in the coldest zone served by the system .
Informative Note: Lower humidity is permitted when operating mechanical cooling for temperature control.
6.4.3.6.2 Humidification. Humidistatic controls shall not use fossil fuel or electricity to produce relative humidity above 30% in the warmest zone served by the system .
6.4.3.6.3 Control Interlock. Where a zone is served by a system or systems with both humidification and dehumidification capability, means (such as limit switches, mechanical stops, or, for DDC systems, software programming) shall be provided capable of and configured to prevent simultaneous operation of humidification and dehumidification equipment .
Exception to 6.4.3.6.1 and 6.4.3.6.2: Systems serving zones where specific humidity levels are
required, such as museums and hospitals, and approved by the authority having jurisdiction or
ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 79