23 09 93 Sequence of Operations for HVAC Controls

7.Shall have an LED display independently showing the status of serial communication, running, errors, power, all digital outputs, and all analog inputs.

8.Shall accept the following inputs: space temperature, setpoint adjustment, outdoor air temperature, indoor air qu- ality, outdoor air quality, compressor lock-out, fire shutdown, enthalpy switch, and fan status/filter status/humid- ity/remote occupancy.

9.Shall provide the following outputs: economizer, fan, cooling stage 1, cooling stage 2, heat stage 1, heat stage 2, heat stage 3/ exhaust/ reversing valve.

10.Shall have built-in surge protection circuitry through solid state polyswitches. Polyswitches shall be used on in- coming power and network connections. Polyswitches will return to normal when the “trip” condition clears.

11.Shall have a battery back-up capable of a minimum of 10,000 hours of data and time clock retention during power outages.

12.Shall have built-in support for Bryant technician tool.

13.Shall include an EIA-485 protocol communication port, an access port for connection of either a computer or a Bryant technician tool, an EIA-485 port for network communication to intelligent space sensors and displays, and a port to connect an optional LonWorks communications card.

14.Software upgrades will be accomplished by either local or remote download. No software upgrades through chip replacements are allowed.

23 09 33 Electric and Electronic Control System for HVAC

23 09 33.13 Decentralized, Rooftop Units:

23 09 33.13.A. General:

1.Shall be complete with self-contained low-voltage control circuit protected by a resettable circuit breaker on the 24-v transformer side. Transformer shall have 75VA capability.

2.Shall utilize color-coded wiring.

3.Shall include a central control terminal board to conveniently and safely provide connection points for vital con- trol functions such as: smoke detectors, phase monitor, economizer, thermostat, DDC control options, loss of charge, freeze switch, high pressure switches.

4.Unit shall include a minimum of one 8-pin screw terminal connection board for connection of control wiring.

5.Shall include integrated defrost system to prevent excessive frost accumulation during heating duty, and shall be controlled as follows:

a.Defrost shall be initiated on the basis of time and coil temperature.

b.A 30,60,90,120 minute timer shall activate the defrost cycle only if the coil temperature is low enough to indic- ate a heavy frost condition.

c.Defrost cycle shall terminate when defrost thermostat are satisfied and shall have a positive termination time of 10 minutes.

6.Defrost system shall also include:

a.Defrost Cycle Indicator LED.

b.Dip switch selectable defrost time between 30,60,90 and 120 minutes. Factory set at 30 minutes.

c.Molded plug connection to insure proper connection.

23 09 33.23.B. Safeties:

1.Compressor over-temperature, over current.

2.Loss of charge switch.

a.Units with 2 compressors shall have different sized connectors for the circuit 1 and circuit 2 low and high pres- sure switches. They shall physically prevent the cross-wiring of the safety switches between circuits 1 and 2.

b.Loss of charge switch shall use different color wire than the high pressure switch. The purpose is to assist the installer and service technician to correctly wire and or troubleshoot the rooftop unit.

3.High-pressure switch.

b.High pressure switch shall use different color wire than the low pressure switch. The purpose is to assist the installer and service technician to correctly wire and or troubleshoot the rooftop unit.

4.Freeze protection thermostat, evaporator coil.

5.Automatic reset, motor thermal overload protector.

23 09 93 Sequence of Operations for HVAC Controls

23 09 93.13 Decentralized, Rooftop Units:

23 09 93.13 INSERT SEQUENCE OF OPERATION

548J

Bryant 548J manual 23 09 93 Sequence of Operations for HVAC Controls

Models: 548J

23 09 93 Sequence of Operations for HVAC Controls