840 N BROADWAY 2017-08-21 - Laserfiche WebLink

1.1. Required differential pressure;or wet-bulb temperature shall meet the energy 1.2. Reset directly based on zone hydronic efficiency requirement for axial fan open-circuit demand,or other zone load indicators;or cooling towers listed in Table C403.2.3(8). 1.3. Reset directly based on pump power and Exception:Centrifugal open-circuit cooling pump differential pressure. towers that are designed with inlet or discharge 2. For systems having a combined pump motor ducts or require external sound attenuation. horsepower that exceeds 20 hp(15 kW)or C403.4.3.3 Tower flow turndown.Open-circuit smaller systems with direct digital control, cooling towers used on water-cooled chiller systems pump speed shall be a function of either: that are configured with multiple-or variable-speed 2.1. The static pressure set point as reset condenser water pumps shall be designed so that all based on the valve requiring the most open circuit cooling tower cells can be run in parallel pressure;or with the larger of the flow that is produced by the 2.2. Directly controlled based on zone smallest pump at its minimum expected flow rate or hydronic demand. at 50 percent of the design flow for the cell. C403.4.3 Heat rejection equipment.Heat rejection C403.4.4 Requirements for mechanical systems equipment such as air-cooled condensers,dry coolers, serving multiple zones.Sections C403.4.4.1 through open-circuit cooling towers,closed-circuit cooling C403.4.4.4 shall apply to mechanical systems serving towers and evaporative condensers used for comfort multiple zones. Supply air systems serving multiple cooling applications shall comply with this section. zones shall be VAV systems which,during periods of • Exception:Heat rejection devices where energy use occupancy,are designed and configured to reduce is included in the equipment efficiency ratings listed primary air supply to each zone to one of the following in Tables C403.2.3(1)A,C403.2.3(1)B, before reheating,recooling or mixing takes place: C403.2.3(1)C,C403.2.3(2),C403.2.3(3), 1. Thirty percent of the maximum supply air to C403.2.3(7)and C403.2.3(9). each zone. C403.4.3.1 Fan speed control.The fan speed shall 2. Three hundred cfm(142 L/s)or less where the be controlled as provided in Sections C403.4.3.1.1 maximum flow rate is less than 10 percent of the and C403.4.3.1.2. total fan system supply airflow rate. ■ 3. The minimum ventilation requirements of C403.4.3.1.1 Fan motors not less than 7.5 hp. Chapter 4 of the International Mechanical Code. Each fan powered by a motor of 7.5 hp(5.6 kW)or larger shall have controls that automatically change 4. Any higher rate that can be demonstrated to the fan speed to control the leaving fluid reduce overall system annual energy use by temperature or condensing temperature/pressure of offsetting reheat/recool energy losses through a the heat rejection device. reduction in outdoor air intake for the system,as approved by the code official. C403.4.3.1.2 Multiple-cell heat rejection 5. The airflow rate required to comply with equipment.Multiple-cell heat rejection equipment applicable codes or accreditation standards,such with variable speed fan drives shall be controlled in as pressure relationships or minimum air change both of the following manners: rates. 1. To operate the maximum number of fans allowed that comply with the manufacturer's Exception:The following define where requirements for all system components. individual zones or where entire air distribution 2. So all fans can operate at the same fan speed systems are exempted from the requirement for required for the instantaneous cooling duty, VAV control: as opposed to staged(on/off)operation. 1. Zones or supply air systems where at least Minimum fan speed shall be the minimum 75 percent of the energy for reheating or allowable speed of the fan drive system in for providing warm air in mixing systems accordance with the manufacturer's is provided from a site-recovered or recommendations. site-solar energy source. C403.4.3.2 Limitation on centrifugal fan 2. Zones where special humidity levels are open-circuit cooling towers.Centrifugal fan required to satisfy process needs. open-circuit cooling towers with a combined rated 3. Zones with a peak supply air quantity of capacity of 1,100 gpm(4164 Urn)or greater at 95°F 300 cfm(142 L/s)or less and where the (35°C)condenser water return,85°F(29°C) flow rate is less than 10 percent of the condenser water supply,and 75°F(24°C)outdoor air total fan system supply airflow rate. 2015 Washington State Energy Code CE-65 S��