SECTION 15985

SEQUENCE OF OPERATION

PART 1 GENERAL

SECTION INCLUDES

Cabinet heaters.

Central refrigeration system.

Central fan system.

Combustion air unit heaters.

Electrical rooms and telephone rooms.

Elevator machine room.

Emergency generator.

Excess pressure control.

Fan coil units.

Heating Coils.

Heating water zone control.

Humidifier.

Induction units.

Parking garage ventilation system.

Radiant panel.

Radiation [and convectors].

Refrigeration system.

Terminal air units

Unit heaters.

RELATED SECTIONS

Section 15973 - Pneumatic Control Systems.

Section 15975 - Direct Digital Control Systems.

SYSTEM DESCRIPTION

This Section defines the manner and method by which controls function. Requirements for each type of control system operation are specified. Equipment, devices, and system components required for control systems are specified in other Sections.

SUBMITTALS

Submit under provisions of Section [01300.] [01340.]

Submit diagrams indicating mechanical system controlled and control system components. Label with settings, adjustable range of control and limits. Include written description of control sequence.

Include flow diagrams for each control system, graphically depicting control logic.

Include draft copies of graphic displays indicating mechanical system components, control system components, and controlled function status and value.

PROJECT RECORD DOCUMENTS

Submit documents under provisions of Section [01700.] [01720.]

Accurately record actual setpoints and settings of controls, including changes to sequences made after submission of shop drawings.

PART 2 PRODUCTS

Not Used

PART 3 EXECUTION

CABINET HEATERS

Single temperature [electric] [room] [pneumatic] thermostat [mounted in cabinet return air] set at [68] [_____] degrees F ([20] [_____] degrees C) maintains constant space temperature by cycling unit fan motor.

Single temperature thermostat on return heating water line [from floor mounted cabinet heaters] de-energizes unit on temperatures below [95] ([_____] degrees F ([35] [_____] degrees C).

Single temperature [room] thermostat [mounted in cabinet return air] set [68] [_____] degrees F ([20] [_____] degrees C) maintains constant space temperature by cycling unit fan motor and electric heating elements. [Integral thermostat continues fan operation until element temperature falls below [100] [_____] degrees ([38] [_____] degrees C).]

CENTRAL REFRIGERATION SYSTEM

Time Schedule: Start and stop condensing water pump.

Condensing Water Pump: Allow start on proof of water in cooling tower sump and on outdoor temperatures above [50] [_____] degrees F ([10] [_____] degrees C). [Start on demand from ventilation system.]

Energize chilled water pump to start and allow cooling tower fans to start when condensing water pump started.

When chilled water pump starts, open chiller control valve. Modulate chiller control valve to maintain constant flow through chiller.

When chilled water flow and condensing water flow are proven by flow switches, allow refrigeration machine to start.

Maintain minimum condenser water temperature of [55] [75] [_____] degrees F ([13] [24] [_____] degrees C) by cycling cooling tower fans.

Maintain temperature in cooling tower sump of 40 degrees F ([4.5] [_____] degrees C) by cycling electric sump heaters. Outdoor thermostat set at [35] [_____] degrees F ([2] [_____] degrees C) shall activate electric heat tapes.

Thermostat in cooling tower sump, set at [35] [_____] degrees F ([2] [_____] degrees C), opens drain lines, closes make-up valve, and deactivates sump heaters and piping electric heat tapes.

Display:

System graphic.

Condensing water pump on/off indication.

Chilled water pump on/off switch.

Chiller on/off indication.

Chiller condensing water supply and return temperature.

Chiller chilled water supply and return temperature.

Chiller condensing water control point adjustment.

Common chilled water control point adjustment.

Low level cooling tower sump alarm.

Expansion tank low level alarm.

Cooling tower fan on/off indication.

Cooling tower sump heater on/off indication.

Cooling tower dump indication.

Chilled water control point adjustment.

Condensing water pump on/off [auto] switch.

Chilled water pump on/off/auto switch.

Chiller on/off [auto] switch.

CENTRAL FAN SYSTEM

Time Schedule: Start and stop supply and return fans. Determine fan status [through auxiliary contactors in motor starter and] by pressure differential switches. If fan fails to start as commanded, signal alarm.

Safety Devices:

Freeze Protection: Stop fans [and close outside air dampers] if temperature [before supply fan] [downsteam of preheat coil] [and in preheat coil return line] is below 37 degrees F (3 degrees C); signal alarm.

High Temperature Protection: Stop fans and close outside dampers if temperature in return air is above 300 degrees F (150 degrees C); signal alarm.

Smoke Detector: Stop fans, close outside dampers, and close smoke dampers if smoke is detected; signal alarm.

Preheat Coil:

When fan is "off", and outside air temperature is below 40 degrees F (5 degrees C), fully open preheat coil valve to heating.

When fan is "on", maintain constant [mixed air] [supply air] temperature of 55 degrees F (12 degrees

by modulating preheat coil valve.

Outside Air Damper: When supply fan is "on", open [minimum] outside air damper. [Prevent supply fan starting until outside air damper is open and position is verified.]

Humidifier: When supply fan is "on" [and there is water in humidifier sump], humidistat located in return air, reset from outdoors [modulates normally closed humidifier valve.] [cycles spray pumps.] [and modulates valve on spray header.] Set outdoor reset to 50 percent relative humidity at 70 degrees F (21 degrees C) and 15 percent relative humidity at -30 degrees F (-35 degrees C).

Outside, Return, and Relief Dampers:

When supply fan is "off, outside and relief dampers are closed and return damper is open.

When supply fan is "on", dampers are controlled and operate with outside and relief dampers opening, and return damper closing.

For cooling and outside air temperatures below 55 degrees F (12 degrees C), modulate dampers to maintain [mixed] [supply] air temperature of 55 degrees F (12 degrees C)[.] [or higher.]

For cooling and outside air temperatures between 55 and 70 degrees F (12 and 21 degrees C) outside and relief dampers are open and return damper is closed.

For cooling and outside air temperatures between 70 and 79 degrees F (21 and 26 degrees C) compare return and outside air temperatures. If return air temperature is lower, drive outside damper to minimum, close relief damper, and open return damper.

For outside air temperatures above 79 degrees F (26 degrees C), drive outside damper to minimum, close relief damper, and open return damper.

For heating, drive outside damper to minimum, close relief damper, and open return damper.

Modulate [mixed air dampers] [preheat coil valve] [and face and bypass dampers] [and cooling coil valve] in sequence to maintain [constant] [mixed] [supply] air temperature.

Multizone System:

[Single] [Dual] temperature room thermostat set at [75] [___] degrees F ([24] [___] degrees C) maintains constant space temperature [during the day and 15 degrees F (8 degrees C) cooler at night] by modulating zone dampers.

Room thermostat calling for greatest heating modulates reheat coil valve. [Room thermostat calling for greatest cooling modulates cooling coil valve.]

Dual Duct System:

Control hot deck temperature in accordance with outdoor reset schedule by modulating reheat coil valve.

Control hot deck at maximum 135 degrees F (57 degrees at outdoor temperature of -30 degrees F (-35 degrees C), and minimum 75 degrees F (24 degrees C) at outdoor temperature of 75 degrees F (24 degrees C), with straight line relationship between.

Maintain constant cold deck temperature of 55 degrees F (12 degrees C) by modulating cooling coil valve.

Induction System:

Control hot deck temperature in accordance with outdoor reset schedule by modulating reheat coil valve.

Control zone supply temperature at maximum 135 degrees F (57 degrees C) at outdoor temperature of -30 degrees F (-35 degrees C), and minimum 55 degrees F (12 degrees C) at outdoor [solar compensated] temperature of 75 degrees F (24 degrees C), with straight line relationship between, by modulating reheat coil valve.

Maintain constant supply static pressure of [1.5] [_____] inches wg ([380] [_____] Pa) by modulating supply and return fan inlet vane dampers in sequence. Locate sensor minimum [50] [_____] ft ([15] [_____]m) downstream of supply fan in supply air duct.

Maintain constant supply static pressure of [1.5] [_____] inches wg ([380] [_____] kPa) by modulating supply fan inlet vane dampers. Maintain constant building pressure of [0.05] [_____] inches wg ([12] [_____] kPa) measured at grade by modulating return air fan inlet vane dampers.

Maintain constant supply static pressure of [1.5] [_____] inches wg ([380] [_____] kPa) by modulating supply fan inlet vane dampers. Maintain constant differential air flow rate between supply and return by modulating return fan inlet vane dampers from velocity pressure measurements in supply and return ducts.

Display:

System graphic.

System on/off indication.

System day/night mode indication.

System fan on/off indication

Return fan on/off indication.

Preheat coil pump on/off indication.

Spray pump on/off indication.

Outside air temperature indication.

Mixed air temperature indication.

Fan discharge air temperature indication.

Reheat zone air temperature indication.

Return humidity indication.

Fan discharge temperature control point adjustment.

Return humidity control point adjustment.

Reheat zone control point adjustment.

Supply static pressure indication.

Supply static pressure control point adjustment.

Building static pressure indication.

Building static pressure control point adjustment.

System on/off auto switch.

System day/night/auto switch.

Supply fan on/off switch.

Return fan on/off/auto switch.

Preheat coil pump on/off switch.

Spray pump on/off auto switch.

COMBUSTION AIR UNIT HEATERS

Single temperature room thermostat set at [68] [_____] degrees F ([20] [_____] degrees C) maintains constant room temperature by modulating [two-way] [three-way] heating control valve.

Single temperature thermostat on return heating water line de-energizes unit fan on temperatures below [95] [_____] degrees F ([35] [_____] degrees C).

ELECTRICAL ROOMS AND TELEPHONE ROOMS

On room temperatures above [95] [_____] degrees F ([35] [_____] degrees C) [open intake damper and] start [exhaust] fan.

ELEVATOR MACHINE ROOM

On room temperatures above [85] [_____] degrees F ([30] [_____] degrees C), open intake dampers and start exhaust fans.

On room temperatures above [90] [_____] degrees F ([32] [_____] degrees C), signal alarm.

EMERGENCY GENERATOR

When generator is "off", outside and exhaust dampers are closed and recirculation damper is open.

When generator is "on", dampers are controlled and operate with outside and exhaust dampers opening, and recirculating dampers closing, to maintain room temperature of [85] [_____] degrees F ([30] [_____] degrees C).

On room temperatures above [95] [_____] degrees F ([35] [_____] degrees C) open intake damper and start exhaust fan.

Provide solenoid valve to shut off fuel supply when generator is not operating.

EXCESS PRESSURE CONTROL

Maintain constant pressure differential between supply and return lines by [modulating bypass valve.] [cycling pumps in sequence.] [varying pump speed through variable speed drive control.]

FAN COIL UNITS

[Single] [Dual] temperature unit mounted thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) maintains constant space temperature [during the day and [15] [_____] degrees F ([8] [_____] degrees C) cooler at night] by [modulating] [opening and closing] two-way control heating valve [with spring range of [3 to 7 psig (20 to 48 kPa)] [3 to 13 psig (20 to 90 kPa)].]

[Single] [Dual] temperature unit mounted thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) maintains constant space temperature [during the day and [15] [___] degrees F ([8] [_____] degrees C) cooler at night] by [modulating] [opening and closing] two-way control heating valve [with spring range of 3 to 7 psig (20 to 48 kPa)] [and two-way cooling control valve [with spring range of 8 to 13 psig (55 to 90 kPa)] in sequence.

[Single] [Dual] temperature unit mounted thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) maintains constant space temperature [during the day and [15] [_____] degrees F ([8] [_____] degrees C) cooler at night] by modulating four-way control valve. During heating cycle, modulate hot water supply to coil and divert return water to heating return pipe. During cooling cycle, modulate chilled water supply to coil and divert return water to cooling return pipe. When space temperature is at thermostat setting, prevent flow from occurring in either circuit and in coil.

Change over from heating to cooling by indexing thermostat from thermostat on supply piping. When supply is above room temperature, operate thermostat in direct acting manner, opening valve when temperature falls below thermostat setting. When supply is below room temperature, operate thermostat in reverse acting manner, opening valve when space temperature rises above thermostat setting.

For heating and cooling fan coil units with fan speed control during heating cycle, increase fan speed as space temperature falls below thermostat setting, provided hot water is available. During cooling cycle, increase fan speed as space temperature rises above thermostat setting, provided chilled water is available.

Mount thermostat with adjustable knob and speed switch on common plate engraved with "Heating Control and Fan Control" on top, with "Warmer and Cooler" and direction indicator around the thermostat knob.

HEATING COILS

[Single] [Dual] temperature thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) maintains constant space temperature [during the day and [15] [_____] degrees F ([8] [_____] degrees C) cooler at night] by [modulating] [opening and closing] [two-] [three-] way control heating valve [with spring range of [3 to 7 psig (20 to 48 kPa)] [3 to 13 psig (20 to 90 kPa)].]

Single temperature room thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) maintains constant space temperature by [energizing] [staging] [modulating electric output through action at SCR power controller, to] electric heaters.

HEATING WATER ZONE CONTROL

[Flow] [Pressure] switch in heating pump discharge provides on/off indication.

Control heating water supply temperature [set at [195] [_____] degrees F ([90] [_____] degrees C)] [in accordance with outdoor reset schedule] by [modulating steam control valve.] [modulating heating water control valve.] [modulating boiler gas valve.] [step firing boilers.]

Control heating water at maximum [195] [_____] degrees F ([90] [_____] degrees C) at outdoor temperature of [-30] [_____] degrees F ([-35] [_____] degrees C), and minimum [130] [_____] degrees F ([54] [_____] degrees C) at outdoor temperature of [75] [_____] degrees F ([24] [_____] degrees C), with straight line relationship

between.

Step fire boilers in sequence, [Boiler No. 1 - low fire, Boiler No. 1 - high fire, Boiler No. 2 - low fire, Boiler No. 2 - high fire.] [______________________________.]

[Flow] [Pressure] switch in heating water circuit on no flow conditions [closes valve and] indicates alarm.

On outside temperatures above [65] [_____] degrees F ([18] [_____] degrees C), de-energize heating pumps and suppress alarm.

Display:

System graphic.

System supply temperature.

System supply control point adjustment.

System return temperature.

Pump on/off indication.

Pump on/off switch.

Boiler lead lag switch.

HUMIDIFIER

When fan is "on" [and air flow switch proves air flow], line voltage room humidistat [reset from outdoors] maintains humidity [level of [30] [_____] percent] by [cycling unit fan and] [opening two position] [modulating] two-way [steam] [hot water] valve.

When supply fan is "on" [and air flow switch proves air flow], [and there is water in humidifier sump], humidistat located in return air, reset from outdoors [modulates normally closed humidifier valve] [cycles spray pumps] [and modulates valve on spray header]. Set outdoor reset to [50] [_____] percent relative humidity at [70] [_____] degrees F ([21] [_____] degrees C) and [15] [_____] percent relative humidity at [-30] [_____] degrees F ([-35] [_____] degrees C).

INDUCTION UNITS

[Single] [Dual] temperature unit mounted thermostat maintains constant space temperature at [75] [_____] degrees F ([24] [_____] degrees C) during the day and [60] [_____] degrees F ([16] [_____] degrees C) cooler at night] by [modulating] [opening and closing] two-way control heating valve [with spring range of [3 to 7 psig (20 to 48 kPa)] [3 to 13 psig (20 to 90 kPa)] [8 to 13 psig (55 to 90 kPa)].]

PARKING GARAGE VENTILATION SYSTEM

Time Schedule: Stop exhaust fan at night.

Carbon Monoxide (CO) detector maintains maximum CO level of 50 ppm by cycling exhaust fan. When CO level exceeds 100 ppm, signal alarm.

When exhaust fan starts, start make-up unit.

RADIANT PANEL

[Single] [Dual] temperature thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) shall maintain constant space temperature [during the day and [15] [_____] degrees F ([8] [_____] degrees C) cooler at night] by [modulating] [opening and closing] two-way control heating valve [with spring range of [3 to 7 psig (20 to 48 kPa)] [3 to 13 psig (20 to 90 kPa)].]

[Single] [Dual] temperature thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) shall maintain constant space temperature [during the day and [15] [_____] degrees F ([8] [_____] degrees C) cooler at night] by modulating four-way control valve. During heating cycle, modulate hot water supply to coil, and divert return water to heating return pipe. During cooling cycle, modulate chilled water supply to coil and divert return water to cooling return pipe. When space temperature is at thermostat setting, prevent flow from occurring in either circuit and in coil.

Change over from heating to cooling by indexing thermostat from aquastat on supply piping. When supply is above room temperature, operate thermostat in direct acting manner, opening valve when temperature falls below thermostat setting. When supply is below room temperature, operate thermostat in reverse acting manner, opening valve when space temperature rises above thermostat setting.

RADIATION [AND CONVECTORS]

[Single] [Dual] temperature thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) maintains constant space temperature [during the day and [15] [_____] degrees F ([8] [_____] degrees C) cooler at night] by [modulating] [opening and closing] two-way control heating valve [with spring range of [3 to 7 psig (20 to 48 kPa)] [3 to 13 psig (20 to 90 kPa)].]

Single temperature room thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) maintains constant space temperature by [energizing] [staging] [modulating electric output through action at SCR power controller, to] electric heaters.

REFRIGERATION SYSTEM

Maintain constant [supply] [return] air duct temperature of [55 degrees F (13 degrees C)] [75] [_____] degrees F ([24] [_____] degrees C)] [__________] by cycling refrigeration system and signalling step capacity, minimum of [__________] steps.

TERMINAL AIR UNITS

[Single] [Dual] temperature thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) maintains constant space temperature [during the day and [15] [_____] degrees F ([8] [_____] degrees C) cooler at night] by [modulating] [opening and closing] two-way control heating valve [with spring range of [3 to 7 psig (20 to 48 kPa)] [3 to 13 psig (20 to 90 kPa)].]

[Single] [Dual] temperature thermostat set at [75] [_____] degrees F ([24] [_____] degrees C) maintains constant space temperature by modulating [variable volume damper] [and] [dual duct damper] operator.

Where reheat coils or radiation is also provided, sequence two-way heating control valve with damper operator[.] [having spring range of 8 to 13 psig (55 to 90 kPa).]

UNIT HEATERS

Single temperature electric room thermostat maintains constant space temperature of [68] [_____] degrees F ([20] [_____] degrees C) by cycling unit fan motor.

Single temperature thermostat on return heating water line [from floor mounted cabinet heaters] de-energizes unit on temperatures below [95] [_____] degrees F ([35] [_____] degrees C).

Single temperature room thermostat set at [68] [_____] degrees F ([20] [_____] degrees C) maintains constant space temperature by cycling unit fan motor and energizing electric heating elements. [Integral thermostat continues fan operation until element temperature falls below [100] [_____] degrees F ([38] [_____] degrees C).]

END OF SECTION