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PART 0 A/E INSTRUCTIONS 0.01 SYSTEM DESCRIPTION

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PART 0 A/E INSTRUCTIONS 0.01 SYSTEM DESCRIPTION A. Design Requirements: 1. General: a) The intent of this Design Guide Section is to provide the A/E with representative control sequences and point/data
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PART 0 A/E INSTRUCTIONS 0.01 SYSTEM DESCRIPTION A. Design Requirements: 1. General: a) The intent of this Design Guide Section is to provide the A/E with representative control sequences and point/data lists that the District has found satisfactory to use as an example in the final design of typical projects. b) The typical systems described are simple solutions to typical control designs. Before using them, be sure the control design for the project system is typical. Be aware that the final design is the responsibility of the Design Consultant. c) The District requires functional performance testing of the complete control system prior to Owner acceptance. 2. Kitchen suites with Make-up Units: a) Make-up air for kitchen hoods shall be controlled in sequence with the kitchen exhaust hood. (See Division 16 for hood and make-up unit controls). b) Make-up unit will run only when kitchen hood is on. c) Supplemental heat shall be provided via baseboard radiation units located at all rooms with exterior exposures. The radiation units shall be controlled by a separate thermostat. PART 1 GENERAL 1.01 SUMMARY A. Section Includes: 1. Hot water heating 2. Chilled Water Cooling 3. Air Handling Units (VAV) 4. Terminal Units PART 2 PRODUCTS Not used. PART 3 EXECUTION 3.01 SEQUENCE OF OPERATION A. VAV Air Handler: 1. The occupancy mode (occupied-unoccupied) shall be determined through a user-adjustable, graphical, seven-day schedule with an additional holiday schedule. a) Occupied Mode: i) All fans shall have a starter with hand-off-auto switch or a Variable Frequency Drive (VFD). When the starter switch is in the hand position, the fan shall run. When the switch is in the off position the fans shall stop. When the switch is in the auto position, the fan shall be under the control of the DDC Controls System. When the fan is controlled by the VFD, the DDC Control System shall interface with the VFD controller and make all monitoring and control points available to the DDC System. The VFD shall have a by-pass switch to allow for manual operation of the fan when the VFD is not operational Page 1 of 17 15985 Page 2 of 17 The supply fan shall be energized. The supply fan speed shall modulate to maintain duct static pressure setpoint (adjustable). The final setpoint shall be determined in consultation with the balancing contractor. Initial duct static pressure setpoint shall be 1.0 w.g. (adjustable). Provide a high static alarm when the duct static pressure rises above 3.0 w.g. (adjustable). ii) Whenever the supply fan is energized, the return/exhaust fan shall be energized. The return fan speed shall modulate to maintain the return Building static pressure setpoint of 0.10 w.g. (adjustable). iii) The exhaust air damper shall modulate to maintain the space static pressure setpoint of 0.05 w.g (adjustable). Building static pressure sensors shall be located in a space where there will be small changes in the pressure between inside and outside pressure changes. Recommended places: Second floor corridors, common spaces, offices, or library. Do not locate sensor near elevators or exterior doors. iv) Discharge air temperature setpoint shall be reset based upon return air temperature according to the following reset schedule. All parameters shall be independently adjustable. The cooling coil control valve shall modulate to maintain the discharge air temperature setpoint, 55 degrees F (adjustable). The heating coil control valve shall modulate to maintain the discharge air temperature as described below. Discharge air temperature setpoint is 55 degrees F (adjustable) when outdoor temperature is greater than 70 degrees F. Discharge air temperature setpoint is 65 degrees F (adjustable) when outdoor temperature is less than 30 degrees F. v) Economizer Control: Whenever the outside air temperature is above the space temperature (75 degrees F, cooling; 72 degrees F, heating) the outside air and return air dampers shall positioned for the minimum outside air scheduled. Or the CO2 sensor in the return air duct shall modulate the outside and return air dampers to maintain the minimum outside air required for the occupancy. When the outside air temperature is below 55 degrees F (adjustable), the outside and return air dampers shall be positioned to maintain the mixed air temperature. vi) Indirect tower cooling (where applicable for evaporative cooling) Fill the tower sump if the outside air temperature is above 55 degrees F (adjustable). Maintain tower sump water temperature by cycling tower fan s off-low-high using a local temperature controller mounted to the tower sump. Provide hardwired time delay internal to the magnetic motor starter when going from fan high-speed to low-speed to allow for fan deceleration. The tower sump shall drain to the interior sump whenever the outdoor air temperature is below 35 degrees F (adjustable) for 60 minutes (adjustable). vii) Filter Status: A differential pressure switch across the filter shall signal an alarm the DDC system when the pressure drop across the filter is above the allowed minimum (adjustable). In addition, provide a magnic-helic gauge to indicate dirty filters. b) Unoccupied Mode: i) The supply and return fans shall be de-energized. Both outdoor air dampers and exhaust dampers shall be closed. The return air damper shall be open. ii) The heating coil valve and pump shall cycle to maintain mixed-air temperature of 45degrees F (adjustable). iii) The supply fan shall cycle to maintain the unoccupied setpoint temperature (65 F, adjustable). iv) If the unoccupied space temperature is not maintained the heating control valve shall modulate to maintain the space temperature. And the supply fan shall cycle on. c) Morning Warm-up: i) When the outside air temperature is below 55 degrees F, the DDC system shall perform a morning warm-up cycle prior to the occupied mode. ii) The outside air damper shall be closed and the return air damper shall be open. iii) The supply fan shall energize and the heating coil control valve shall open. iv) The Air Handling Unit shall remain in the morning warm-up mode until the return air temperature is 70 degrees F. After the system has achieved 70 degrees F (adjustable) the system shall enter the Occupied Mode. d) Safety Shutdowns: i) Duct smoke detection, high-pressure safeties and low-temperature limit trips shall deenergize the air-handling unit supply and return fans and close the outdoor air and exhaust air dampers. Manual reset shall be required to allow the fans to operate. e) Freeze Protection: i) When the outdoor air temperature is below 40degrees F (adjustable), the HW and CHW pumps shall be energized continuously for freeze protection. The heating coil valve shall cycle as described elsewhere. ii) If the unit has shutdown on the low temperature limit switch, energize the return fan until the condition has been resolved. B. Make-Air Unit (Gas-fired): 1. The occupied-unoccupied shall be determined by the kitchen exhaust fan status through a useradjustable, graphical, seven-day schedule with an additional holiday schedule with the DDC system. a) Occupied Mode: i) All fans shall have a starter with hand-off-auto switch. When the starter switch is in the hand position, the fan shall run. When the switch is in the off position the fans shall stop. When the switch is in the auto position, the fan shall be under the control of the DDC Controls System. The fan shall energize and run with the kitchen exhaust fan. When the exhaust fan is on the Make-up Unit shall run. ii) Discharge air temperature setpoint shall be reset based upon outdoor air temperature according to the following reset schedule. All parameters shall be independently adjustable. The cooling coil (if provided) control valve shall modulate to maintain the discharge air temperature setpoint, 55degrees F (adjustable). The gas-fired heat exchanger shall have a modulating gas valve that shall modulate to maintain the discharge air temperature as described below: 01) Discharge air temperature setpoint is 55degrees F (adjustable) when outdoor temperature is greater than 70degreesF Page 3 of 17 02) Discharge air temperature setpoint is 65degrees F (adjustable) when outdoor temperature is less than 30degrees F. iii) Indirect tower cooling (where applicable for evaporative cooling) Fill the tower sump if the outside air temperature is above 55degrees F (adjustable). Maintain tower sump water temperature by cycling tower fan s off-low-high using a local temperature controller mounted to the tower sump. Provide hardwired time delay internal to the magnetic motor starter when going from fan high-speed to low-speed to allow for fan deceleration. The tower sump shall drain to the interior sump whenever the outdoor air temperature is below 35 degrees F (adjustable) for 60 minutes (adjustable). iv) Filter Status: A differential pressure switch across the filter shall signal an alarm when the pressure drop across the filter is above the allowed minimum (adjustable). Provide a local light to indicate that the filter is to be changed. Red shall indicate filter to be changed. Green shall indicate that filter is adequate. In addition, provide a magnic-helic gauge to indicate dirty filters. b) Unoccupied Mode: i) The supply fan shall be de-energized. The outdoor air damper shall close. ii) The fan coil units or radiant heating control valve shall modulate to maintain the space temperature of 55degrees F (adjustable). C. Constant Volume Air Handler : 1. The occupancy mode (occupied-unoccupied) shall be determined through a user-adjustable, graphical, seven-day schedule with an additional holiday schedule. a) Occupied Mode: i) All fans shall have a starter with hand-off-auto switch. When the starter switch is in the hand position, the fan shall run. When the switch is in the off position the fans shall stop. When the switch is in the auto position, the fan shall be under the control of the DDC Controls System. The supply fan shall be energized. ii) Whenever the supply fan is energized, the return/exhaust fan shall be energized. iii) Discharge air temperature setpoint shall be reset based upon outdoor air temperature according to the following reset schedule. All parameters shall be independently adjustable. The cooling coil control valve shall modulate to maintain the discharge air temperature setpoint, 55 degrees F (adjustable). The heating coil control valve shall modulate to maintain the discharge air temperature as described below. 01) Discharge air temperature setpoint is 55 degrees F (adjustable) when outdoor temperature is greater than 70 degrees F. 02) Discharge air temperature setpoint is 65 degrees F (adjustable) when outdoor temperature is less than 30 degrees F. The local DDC Controller shall modulate the Re-heat coils control valve in the zone duct to maintain the space setpoint, 72 degrees F. iv) Economizer Control: Whenever the outside air temperature is above the space temperature (75 degrees F, cooling; 72 degrees F, heating) the outside air and return air dampers shall positioned for the minimum outside air scheduled. Or the CO2 sensor in Page 4 of 17 the return air duct shall modulate the outside and return air dampers to maintain the minimum outside air required for the occupancy. When the outside air temperature is below 55 degrees F (adjustable), the outside and return air dampers shall be positioned to maintain the mixed air temperature. v) Filter Status: A differential pressure switch across the filter shall signal an alarm when the pressure drop across the filter is above the allowed minimum (adjustable). Provide a local light to indicate that the filter is to be changed. Red shall indicate filter to be changed. Green shall indicate that filter is adequate. b) Unoccupied Mode: i) The supply and return fans shall be de-energized. Both outdoor air dampers and exhaust dampers shall be closed. The return air damper shall be open. ii) The heating coil valve and pump shall cycle to maintain mixed-air temperature of 45 degrees F (adjustable). iii) The supply fan shall cycle to maintain the unoccupied setpoint temperature (65 degrees F, adjustable). iv) If the unoccupied space temperature is not maintained the heating control valve shall modulate to maintain the space temperature. And the supply fan shall cycle on. c) Morning Warm-up: i) When the outside air temperature is below 55 degrees F, the DDC system shall perform a morning warm-up cycle prior to the occupied mode. ii) The outside air damper shall be closed and the return air damper shall be open. iii) The supply fan shall energize and the heating coil control valve shall open. iv) The Air Handling Unit shall remain in the morning warm-up mode until the return air temperature is 70 degrees F. After the system has achieved 70 degrees F (adjustable) the system shall enter the Occupied Mode. d) Safety Shutdowns: i) Duct smoke detection, high-pressure safeties and low-temperature limit trips shall deenergize the air-handling unit supply and return fans and close the outdoor air and exhaust air dampers. Manual reset shall be required to allow the fans to operate. e) Freeze Protection: i) When the outdoor air temperature is below 40degrees F (adjustable), the HW and CHW pumps shall be energized continuously for freeze protection. The heating coil valve shall cycle as described elsewhere. ii) If the unit has shutdown on the low temperature limit switch, energize the return fan until the condition has been resolved CHILLED WATER SYSTEM A. The chiller shall be enabled whenever the outside air temperature is above 55degrees F for 30 minutes (both adjustable). The chiller shall be disabled when the outside air temperature drops below 54 degrees F for 30 minutes (both adjustable). B. Water-Cooled Chiller Control: 1. The chiller shall not be enabled unless the cooling tower sump is filled. 2. The chiller shall start and stop the chilled water and condenser water pumps through its internal controls. 3. The cooling tower fan shall sequence off-low-high to maintain condenser water supply temperature setpoint of 74 degrees F (adjustable). The fan shall be locked out whenever the chiller is de-energized Page 5 of 17 4. The cooling tower sump drain and fill lines shall drain whenever the outdoor air temperature is less than 35 degrees F for 30 minutes (both adjustable). The tower sump shall be filled whenever the outside air temperature is greater than 54 degrees F for 30 minutes (both adjustable). C. The chilled water supply temperature shall be reset from 45 degrees to 52degrees F. 1. The chilled water supply temperature setpoint shall be 52 degrees F when the outdoor air temperature is less than or equal to 55 degrees F. 2. The chilled water supply temperature setpoint shall be 45 degrees F when the outdoor air temperature is greater than or equal to 80 degrees F. D. Activation of any emergency-stop switches or refrigerant-detection alarms shall de-energize all central plant equipment except makeup-air units and exhaust fans. E. Air-Cooled Chiller Control: 1. The chiller shall operate with its associated pump in a lead/lag configuration. 2. The chiller controls shall alternate the lead chiller every 336 hours, minimum. 3. The chilled water system shall be enabled by the DDC System when ever the outside air tempeature is above the setpoint listed above. 4. The chiller shall operate by the micro-processor based control system provided by the manufacturer. The chiller controls shall stage the chiller to maintain the discharge water temperatures listed above. 5. Each chiller shall have a flow switch directly connected to the control chiller panel. The chiller shall not operate unless water flow is proven. 6. All points shall be available to the DDC System. F. Chilled Water Pump Control: 1. The pumps shall be designed for 100% and stand-by operation. The pumps shall be started simultaneously. 2. Each pump shall be provide with a hand-off-auto switch. When the switch is in the hand position the pump shall run. When the switch is in the off position the pump shall be stopped. When the switch is in the auto position, the pump shall be under control of the DDC System. 3. The distribution pumps shall be started and run when the outside air temperature rises 55 F (adjustable). 4. Each Pump status shall be reported through a current sensing relay 3.03 CABINET UNIT HEATER A. A conventional electric space thermostat shall open/close the control valve and cycle the unit fan to maintain space temperature at setpoint of 68degrees F(adjustable). For hot water heating, when heating water is not available as sensed by the aquastat, the fan shall be de-energized UNIT HEATER A. A conventional electric thermostat shall cycle the unit fan to maintain space temperature at setpoint of 68 degrees F. For hot water heating, when heating water is not available as sensed by the aquastat the fan shall be de-energized BASEBOARD HEATING A. Fintube radiation shall be modulated in sequence with the associated VAV box. Heating with Fintube and cooling with the VAV box shall not occur simultaneously. Use non-overlapping spring ranges or sequencing relays on the Fintube control valve and VAV damper actuator VAV BOXES Page 6 of 17 A. DDC Control varies the airflow from maximum to minimum and modulates the heating valve in sequence to maintain the space temperature setpoint. The heating valve shall not begin to open until the airflow has reached its minimum setting Set minimum and maximum CFM as shown on the drawings FACE AND BYPASS PREHEAT COIL (MAKE-UP AIR UNITS ONLY) A. Two-position preheat coil valve shall open full when outside air temperature is below 35 F. Face and bypass dampers shall modulate to maintain 50 F (adjustable) preheat coil discharge air temperature HOT WATER HEATING A. Heating Water Supply (Steam Heat Exchanger): 1. Hot water supply temperature shall be reset inversely with changes in outside temperature locate OA sensor on north exposure). its setting by modulating in sequence, two normally-closed control valves in parallel in the steam supply to the hot water heat exchanger. Fail-safe operation of steam valve shall be to fail closed. B. Zone Control: 1. Building to be zoned as required by floors, orientation and function as determined for specific project. 2. Provide for each zone a night, weekend and holiday setback. 3. Provide each zone with an adjustable morning warm-up time period. C. Temperature reset of a controlled variable is encouraged where overall system energy use will be minimized while still maintaining building temperature control requirements. D. Boiler Control: 1. The boilers shall be enabled or disabled by the DDC System. Packaged boiler conrollers shall modulate the boilers to maintain the heating water supply temperature scheduled (180 F, adjustable). 2. The following points shall be available to the DDC System: a) Enable/Disable the boilers. b) High Temperature Limit c) Low Water Cut-off d) No flow detected e) Manual Shut Down 3. Combustion Air Control: Combustion air dampers shall open when the boiler is enabled. The damper end switch shall prove that the damper is open prior to enableing the boiler. If the damper is not proven open, the DDC System shall sen and alarm and the boilers shall be shut down. E. Heating Water Pumps: 1. Each boiler production (primary) pump shall be provide with a hand-off-auto switch. When the switch is in the hand position the pump shall run. When the switch is in the off position the pump shall be stopped. When the switch is in the auto position, the pump shall be under control of the DDC System. 2. Each production pump shall be started whenever its associated boiler is enabled. 3. Heating water distribution (secondary) pumps shall be provide with a hand-off-auto switch. When the switch is in the hand position the pump shall run. When the switch is in the off position the pump shall be stopped. When the switch is in the auto position, the pu
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