McQuay MPS 025B Installation Manual

Operation Manual OM 1077

DDC Rooftop Unit Controller

Heating & Cooling, Gas/Electric & Electric/Electric Models MPS 003B – 025B 3 to 25 Tons [10.6 to 87.9 kW] R-410A Refrigerant

Group: Applied Air Systems Part Number: OM 1077 Date: August 2010

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Safety Information . . . . . . . . . . . . . . . . . . . . . . . . 3

Third party Building Management System . . . 3

Programmable 24 Volt Thermostat. . . . . . . . . 4

Control Inputs and Outputs . . . . . . . . . . . . . . . . . . 6

Control Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Control Input Descriptions. . . . . . . . . . . . . . . . 6

Control Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Control Output Descriptions . . . . . . . . . . . . . . 8

Unit Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Sequence of Operation. . . . . . . . . . . . . . . . . . . . . 12

Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Heat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Integrated Furnace Control. . . . . . . . . . . . . . 12

Electric Heat . . . . . . . . . . . . . . . . . . . . . . . . . 14

User Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Keypad 15

General information Screen . . . . . . . . . . . . . 16

Unit Status Screen . . . . . . . . . . . . . . . . . . . . 17

Effective Occupancy Screen . . . . . . . . . . . . 17

Temperature Screen. . . . . . . . . . . . . . . . . . . 18

Set points Screen. . . . . . . . . . . . . . . . . . . . . 18

Economizer. . . . . . . . . . . . . . . . . . . . . . . . . . 19

Integrated Furnace Control Screen . . . . . . . 21

Time Delays Screen . . . . . . . . . . . . . . . . . . . 21

Initial Test Sequence . . . . . . . . . . . . . . . . . . 22

Alarm List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

QUICK START - Units with Thermostat Control. 28

Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Introduction

General

Read this manual and any instructions packaged with separate equipment prior to installation. Give this manual to the owner and explain its provisions. The owner should retain this manual for future reference.

Unit Manual

Rooftop unit control configuration OM 1077 BACnet Communication Module IM 1000 LonWorks Communication Module IM 999 Field Installed Accessories IM 921 Maverick I, 3 to 5 ton Installation and Maintenance IM 970 Maverick I, 6 to 12 ton Installation and Maintenance IM 971 Maverick I, 15 to 25 ton Installation and Maintenance IM 972

Safety Information

DANGER

These instructions are intended as an aid to qualified service personnel for proper installation, adjustment, and operation of this unit. Read these instructions thoroughly before attempting installation, adjustment, or operation. Failure to follow these instructions can result in improper installation, adjustment, service or maintenance, possibly resulting in fire, electrical shock, property damage, personal injury, or death.

DANGER

Introduction

NOTICE

This equipment generates, uses, and can radiate radio frequency energy and; if not installed and used in accordance with this instruction manual, may cause interference to radio communications. It has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC rules. These limits are designed to prov i d e reasonable protection against harmful interference when the equipment is operated in a commercial envi ro nment. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at their own expense.

The Maverick I 3 to 25 ton Package has a Rooftop Unit Controller factory mounted and wired in their respective control panel. The DDC Controller is a solid-state microprocessor-based control board that provides flexible control and extensive diagnostics for all unit functions. The DDC Controller through proportional/integral control algorithms perform specific unit functions that govern unit operation in response to; zone conditions, system temperatures, ambient conditions and electrical inputs. The DDC Controller features an LCD display and a five-button keypad for local configuration and direct diagnosis of the system.

The Maverick I 3 to 25 ton Package Air Conditioner with integral Rooftop Unit Controller (DDC Controller) is specifically designed to be applied in three distinct applications:

Third party Building Management System

Before beginning any modification, be sure main disconnect switch is in the “off” position. Failure to do so can cause electrical shock resulting in property damage, personal injury or death. Tag disconnect with a suitable warning label.

CAUTION

Static sensitive components. Discharge any static electrical charge by touching the bare metal inside the control panel before performing any service work. Never unplug cables, circuit board terminal blocks, or power plugs while power is applied to the panel.

In an application where a third party building management is in use or will be incorporated the Maverick I is communication compatible with the system that supports the BACnet Application Specific Controller device profile, LonMark Space Comfort Controller functional profile. This is accomplished with a field installed BACnet or LonMark communication module. The BAS system provides the schedule functions for the DDC controller.

BACnet Communication Module

The BACnet Communication Module allows communication between the DDC Controller and the BACnet network. The communication module translates input and output variables between the DDC Controller protocol and the BACnet protocol.

The BACnet Communication Module is compatible with MSTP EIA-485 daisy chain networks communicating at 38.4 bps. It is compatible with twisted pair, shielded cables.

See IM 1000 for full documentation

LonMark Communication Module

The LonMark Communication Module allows communication between the DDC Controller and a Lon Works Network. The

McQuay OM 1077 3

Introduction

Communication module translates input and output variables between the DDC Controller protocol and the Lon Talk protocol. The Lon Talk Communication Module has been developed to communicate with building automation systems that support the Lon Mark Space Comfort Controller (SCC).

The LonMark Communication Module utilizes an FTT-10A free topology transceiver communicating at 78.8 kbps. It is compatible with Echelon qualified twisted pair cable, Belden 8471 or NEMA Level 4 cables. The Module can communicate up to 1640 ft. with no repeater. The LonWorks limit of 64 nodes per segment applies to this device.

See IM 999 for full documentation

Programmable 24 Volt Thermostat

The Maverick with integral DDC Controller is compatible with programmable 24 volt thermostats. The programmable thermostat can supply the time schedule functions when the DDC controller is not connected to a BAS system. Connections are made via conventional thermostat connection screw terminals on terminal T81. Extensive unit status and diagnostics are displayed on the LCD screen.

Zone sensor with time clock

The Maverick I with integral DDC Controller is compatible with a zone sensor and mechanical or solid state time clock.

The DDC Controller in each Maverick I 3 to 25 ton Package Air Conditioner has many design features that optimize operation, installation and service. Each unit with the DDC Controller has the following features:

Blower On/Off Delay. Adjustable time delay between blower

on and off mode

economizer. The DDC Controller communicates with the ELM for control, setpoint, and diagnostics. The DDC Controller has several choices for controlling the economizer. See Economizer Menu Screen. The ELM monitors the mixed air temperature, return air enthalpy (optional), minimum position set point (local or remote), power exhaust set point, CO2 set point, CO2, and outdoor enthalpy sensor, if selected, to control dampers to an accuracy of ±5% of stroke. The actuator is spring returned to the closed position any time that power is lost to the unit. It is capable of delivering up to 44 inch pounds of torque and is powered by 24VAC.

Unit Diagnostics. The DDC Controller monitors all sensors

and functions related to unit operation to provide critical information and maintain diagnostic code information even if a power failure occurs.

Exhaust Fan Control Modes. Exhaust fans are controlled by

fresh air damper position. Setpoint is adjustable through the unit display and keypad.

Field Changeable Control Parameters. Over 50 different

control parameters allow customization of the unit operation by changing delays, cooling stages, dead bands, and set points.

Minimum Compressor Run Time. Ensures proper oil return

to the compressor.

Comfort Alert. The DDC Controller has two inputs to monitor

optional Copeland Comfort Alerts. The inputs can provide the following information: Locked rotor, Open Circuits, Missing Phase, Reverse Phase, and Welded Contactor.

Smoke Alarm Mode. The input will shutdown the unit and

requires a manual reset. The sensor is used to detect smoke due to fire in the air conditioning or ventilation ducts.

Built-in Control Parameter Defaults. No programming

required.

Compressor Time-off Delay. Adjustable time delay between

compressor shutoff and start up

Dirty Filter Switch Input. The DDC Controller will signal an

increase in static pressure across the air filter, indicating a dirty filter condition.

On Board User Interface Display/Keypad. Displays control

parameters, diagnostic codes, and sensor readings. The keypad allows scrolling through display menu and field configurable changes to be made.

Economizer Control. The economizer is controlled by the

Economizer Logic Module (ELM) that comes with the

Lead Lag Compressor Operation. Stage 1 compressor

operation based on compressor accumulated run time.

Staging. Depending on the unit controls up to 2 stages of

cooling, 2 stages of gas heat, and 2 stages of electric heat.

Active Protection. Provides active unit protection when any

of the following occurs three times within a thermostat cycle: low pressure trip, high pressure trip, gas heat limit trip.

Thermostat Bounce Delay. Protects compressor from short

cycling when mechanical thermostat is used

Warm-up Mode Delay. Adjustable time that the economizer

dampers are kept in the closed position during morning warmup input

4 McQuay OM 1077

Figure 1: Controller Component Locations

Introduction

P5 P11

LED 4

Keypad

MOD1

P10

P13

Comfort Alert

LCD Display

Fan, CC1, CC2, Common

24 VAC

Common

T14

P12

Item Description

P1 Electric heat connector Fan Indoor blower motor connector CC1 Compressor1 connector CC2 Compressor 2 connector

Reversing valve 1, Reversing valve 2, Outdoor

P10 RJ11 connector for factory run test P11 Configurable pins used to set unit type P12 Test Pins to force defrost for heat pump models

Coil temperature sensor 1, Outdoor Coil temperature sensor 2, Outdoor Fan 1, and Outdoor Fan 2 connector Motorized Fresh Air Damper, Economizer Logic Module (ELM), and Smoke Detector connector Return air temperature sensor, Fan proving switch, Clogged filter switch, and Discharge air temperature sensor connector Freeze sensor 1, Freeze sensor 2, Outside air temperature sensor, High pressure switch 1, High pressure switch 2, Low pressure switch 1, and Low pressure switch 2 connector

MOD2

T81

Item Description

Connector to Integrated Furnace Control (IFC) –

P13

T14 Not supported T81 Thermostat screw terminals Common

terminals 24 Volt terminals Comfort

Alert LED4

MOD1 LED

MOD2 LED

provides power and communication between DDC Controller and IFC

Field Installed Space Temperature Sensor with Setpoint and Override, Field configurable 1, and Field configurable 2 terminal block

T erminals used for 24 volt common connections & power supply

Terminals used for 24 volt hot connections & power supply

T erminals used to connect a Comfort Alert module LED4 is blinking when the control has an ALARM

present, solid when power is applied. MOD1 LED blinks when the control is communicating on the internal network between

the IFC and/or economizer MOD2 LED blinks when the control is

communicating between the DDC Controller and field installed communication card

McQuay OM 1077 5

Control Inputs and Outputs

Control Inputs

Table 1: ControlInputs

Item Description Type Option

1 ST - Space temperature Thermistor 10k? Field Installed (optional) 2 RAT - Return Air Temperature Thermistor 10k? Factory Installed 3 SAT - Supply Air Temperature Thermistor 10k? Factory Installed 4 OAT - Outside Air Temperature Thermistor 10k? Factory Installed 5 FS1 - Freeze Stat Thermistor 10k? Factory Installed 6 FS2 - Freeze Stat Thermistor 10k? Factory Installed 7 Field Configurable input #1 Thermistor 10k? Field Installed (optional) 8 Field Configurable input #2 Analog input Field Installed (optional) 9 SPA - Set point Adjustment Resistance input Field Installed (optional)

G - Thermostat fan input 24VAC Field Installed (optional)

†

Y1 - Thermostat 1st stage compressor 24VAC Field Installed (optional)

12 Y2 - Thermostat 2nd stage compressor 24VAC Field Installed (optional) 13 W1 - Thermostat heating demand 24VAC Field Installed (optional) 14 W2 - Thermostat heating demand 24VAC Field Installed (optional) 15 HP1 - High Pressure Switch 1 24VAC Factory Installed 16 LP1 - Low Pressure Switch 1 24VAC Factory Installed

†

HP2 - High Pressure Switch 2 24VAC Factory Installed

18 LP2 - Low Pressure Switch 2 24VAC Factory Installed 19 Smoke Detector 24VAC Factory or Field Installed 20 FP - Fan proving 24VAC Factory Installed 21 CFS - Clogged Filter Switch 24VAC Factory Installed 22 Occupied input 24VAC Field Installed (optional) 23 L1 - Comfort Alert 1 Pulsed 24VDC Factory or Field Installed (optional) 24 L2 - Comfort Alert 2 Pulsed 24VDC Factory or Field Installed (optional) 25 Configuration pins Polarized Plug P11 Factory Installed

a.Heat Pump Only

Control Input Descriptions

(1) ST - Space temperature. The space temperature sensor is

used to measure the building zone temperature. Sensors should be located on an interior building wall.

(2) RAT - Return Air Temperature. The DDC Controller has a

return air temperature input. This input is used to monitor system functionality and to provide diagnostics on how the system is operating. This sensor input can be used in place of the space temperature input. It also acts as a backup in case of a space temperature sensor failure.

(3) SAT - Supply Air Temperature. The DDC Controller has a

supply air temperature input. This input is used to monitor system functionality and to provide diagnostics on how the system is operating.

(4) OAT - Outside Air Temperature. The outdoor air

temperature sensor is factory installed in the unit to monitor the outside temperature. This temperature is used to control the economizer.

(5) FS1 - Freeze Stat. When the thermistor reads a

temperature below 37°F continuously for 15 minutes, the

control will shutdown compressor #1 and continue to run the indoor blower. The system will return to normal operation when the thermistor reads a temperature above 42°F for 15 minutes.

(6) FS2 - Freeze Stat. When the thermistor reads a

temperature below 37°F continuously for 15 minutes, the control will shutdown compressor #2 and continue to run the indoor blower. The system will return to normal operation when the thermistor reads a temperature above 42°F for 15 minutes.

(7) Field Configurable input #1. Used for custom installation

of a 10K ohm temperature sensor (e.g. discharge air temperature sensor installed in supply duct).

(8) Field Configurable input #2. Used for custom installation

of an analog input (e.g. 0-10VDC input from outdoor airflow monitoring station).

(9) SPA - Set point Adjustment. If the set point adjustment is

enabled, then the control will consider the hard wired potentiometer input to determine occupied set points only. If the remote set point adjustment is enabled but the input reads

6 McQuay OM 1077

Control Inputs and Outputs

an invalid number, the control will default back to the occupied set point selection.

(10) G - Thermostat fan input. This is a 24 volt input that is

used to control the indoor fan when the DDC Controller is used in conjunction with a thermostat.

(11) Y1 - Thermostat 1st stage compressor. This is a 24 volt

input that is used to control the first stage of mechanical cooling when the DDC Controller is used in conjunction with a thermostat.

(12) Y2 - Thermostat 2nd stage compressor. This is a 24

volt input that is used to control the second stage of mechanical cooling when the DDC Controller is used in conjunction with a thermostat.

(13) W1 - Thermostat heating demand. This is a 24 volt

input that is used to control the first stage of heating (electric heat or gas heat) when the DDC Controller is used in conjunction with a thermostat.

(14) W2 - Thermostat heating demand. This is a 24 volt

input that is used to control the second stage of heating (electric heat or gas heat) when the DDC Controller is used in conjunction with a thermostat.

(15 &17) HP1, HP2 - High Pressure Switch 1 & 2. When the

HPC is opened, the compressor for that circuit is turned off. The compressor will not be allowed to restart for a minimum of 3 minutes. If three consecutive open conditions occur during an active call for operation, the compressor will be locked out, a diagnostic will appear on the LCD display and communicated to the network if applicable. Cycling the call for operation will restart the compressor. On dual compressor units only the affected compressor circuit is locked out.

(16 & 18) LP1, LP2 - Low Pressure Switch 1 & 2. When the

LPC is opened, the compressor for that circuit is turned off. The compressor will not be allowed to restart for a minimum of 3 minutes. The low pressure switch is ignored during defrost and for the first 90 seconds of compressor run time. If three consecutive open conditions occur during an active call for operation, the compressor will be locked out, a diagnostic will appear on the LCD display and communicated to the Network if applicable. Cycling the call for operation will restart the compressor. On dual compressor units only the affected compressor circuit is locked out.

(19) Smoke Detector. The sensor is only applicable on units

equipped with a smoke detector. The input will shutdown the unit and requires a manual reset. The sensor is used to detect smoke due to fire in the air condition or ventilation ducts.

(20)FP - Fan proving. The unit mounted fan proving switch

monitors the pressure differential across the unit blower to detect when the indoor fan is blowing air. A diagnostic signal is sent to the LCD display if the pressure differential indicates that the indoor blower is not operating. The control will also monitor the system and if the blower is running and is not required a fault will be sent to the DDC Controller.

(21) CFS - Clogged Filter Switch. The unit mounted clogged

filter switch monitors the pressure differential across the return air filters. It is mounted in the filter section and is connected to the DDC Controller. A diagnostic signal is sent to the LCD display if the pressure differential across the filters is at least

0.5" w.c. The contacts will automatically open when the pressure differential across the filters decreases to approximately 0.4" w.c., the clogged filter output is operating, and the clogged filter switch has been closed for at least 2 minutes. The system will continue to operate regardless of the status of the filter switch.

(22) Occupied input (OC). This is a 24 volt input that is used

to control the occupancy (occupied or unoccupied mode) when the DDC Controller is used in conjunction with a zone sensor and solid state time clock.

(23 & 24) L1, L2 - Comfort Alert. The DDC Controller has

two inputs to monitor up to two compressor circuits using optional Copeland Comfort Alerts. The inputs can provide the following information: Locked rotor, Open Circuits, Missing Phase, Reverse Phase, and Welded Contactor. Note: The Comfort Alert sends the Open Circuit Alarm (code 5) only after the fault has been sensed for a minimum of 4 hours.

(25) Configuration pins (P11). The DDC Controller features a

7 pin header (P11) on board for the connection of a configuration key. This 7-position connector allows the controller to determine the unit application mode without a menu entry. Table 2 describes the connections necessary for each one of the possible options. The configuration connector provides a quick and safe way of replacing boards while keeping the proper configuration of the unit.

Table 2: Configuration Connector Parameters

P11 – Unit configuration 1 2 3 4 5 6 7

Cooling only (default for 3-25T) – default Single stage Cooling with 2 stages EH x x Single stage G/E(cool) with 1 stage GH x x Single stage G/E(cool) with 2 stages GH x x 2 stages cool with 2 stages EH x x 2 stages G/E(cool) with 2 stages GH x x Selection is made through the display x x x x

McQuay OM 1077 7

Control Inputs and Outputs

Control Outputs

Table 3: Control Outputs

1 CC1 - Compressor output 1 24VAC 1.5A @ 24VAC, pilot duty 2 CC2 - Compressor output 2 24VAC 1.5A @ 24VAC, pilot duty 3 W1 - Heat output 24VAC 1.5A @ 24VAC, pilot duty 4 W2 - Heat Output 24VAC 1.5A @ 24VAC, pilot duty 5 G - Fan Output 24VAC 1.5A @ 24VAC, pilot duty 6 L - thermostat signal 24VAC 25mA loading

Control Output Descriptions

(3) W1 - Heat output. The DDC Controller has two outputs to

control resistance electric heat.

(1) CC1 - Compressor output 1. The DDC Controller can

control the compressor contactors. The DDC Controller can monitor the system and respond to system faults and comfort alert inputs to shut down the compressors in the event of a failure.

(2) CC2 - Compressor output 2. The DDC Controller can

control the compressor contactors. The DDC Controller can monitor the system and respond to system faults and comfort alert inputs to shut down the compressors in the event of a

(4) W2 - Heat Output. The DDC Controller has two outputs to

control resistance electric heat.

(5) G - Fan Output. The DDC Controller can control the

indoor fan by use of a fan relay.

(6) L - Thermostat signal. The “L” terminal will output a

flash code to an indoor 24 V thermostat equipped with an “L” terminal.

failure.

Table 4: Thermo stat Options

Device Part Number Description

Stand alone 24V thermostat / touch screen 113129801 Up to 2-heat / 2-cool Stand alone 24V thermostat 113129901 Up to 2-heat / 2-cool

Table 5: Zone Sensor Module Wire Guide

Device

Wall mounted sensor w/ tenant override 113117701 18 3 Solid 18 AWG 3/C CL2P Thermostat Wall mounted sensor w/ space point adjustment 113117701 18 3 Solid 18 AWG 3/C CL2P Thermostat

Part Number

Wire Gauge

Conductors Type Listings

8 McQuay OM 1077

Unit Installation

Important - The DDC Controller is shipped with the control disabled so units do not accidentally energize during installation. The commissioning of the rooftop unit therefore requires the configuration of the Occupied Mode menu prior to initial startup. See Effective Occupancy‚ page 17.

DANGER

Before beginning any modification, be sure main disconnect switch is in the “off” position. Disconnect all electric power, including remote disconnect before servicing. Fai lure to do so can cause electrical shock resulting in property damage, personal injury or death. Follow proper lockout/tag out procedures to ensure the power cannot be inadvertently energized.

The unit DDC Controller must have a thermostat or zone sensor input in order to operate the unit. If the zone sensor is not present, or has failed, the unit will use the return air temperature sensor to maintain the occupied setpoint. The flexibility of the unit mode capabilities depends upon the type of zone sensor or thermostat selected to interface with the DDC controller.

The descriptions of the following basic Input Devices used within the DDC controller network are to acquaint the operator with their function as they interface with the various modules. Refer to the unit's electrical schematic for the specific module connection.

Unit Installation

Controls using DC Analog Input/Outputs (Standard Low Voltage Multi-conductor Wire)

Before installing any connecting wiring between the unit and components utilizing a DC analog input/output signal, refer to the unit installation manual for the electrical access locations provided on the unit.

• Use shielded cable for high EMI environments.

Note: Resistance in excess of 2.5 ohms per conductor can

cause deviations in the accuracy of the control s.

• Ensure that the wiring between controls and the unit's

termination point does not exceed two and a half (2.5) ohms per conductor for the length of the run.

• Do not run the electrical wires transporting DC signals in or

around conduit housing high voltage wires.

• Most sensor wire insulation has a voltage rating less than the

line voltage. Route Zone Sensor and Network Cable behind low voltage shield during unit installation per Figure 2. This is necessary to meet NEC and UL 1995 requirements for separation of high and low voltage circuits.

Figure 2: Low Voltage Shielding

Sheilding for Low Voltage Conductors

The following controls are available from the factory for field installation:

Controls using 24 VAC

Before installing any connecting wiring, refer to the unit installation manual for AC conductor sizing guidelines “Field Wire Size For 24 Volt Thermostat Circuits”, for the electrical access locations provided on the unit, and;

• Use copper conductors unless otherwise specified.

• Ensure that the AC control wiring between the controls and

the unit's termination point does not exceed three (3) ohms per conductor for the length of the run.

Note: Resistance in excess of 3 ohms per conductor may

cause component failure due to insufficient AC voltage supply.

• Be sure to check all loads and conductors for grounds,

shorts, and mis-wirings.

• Do not run the AC low voltage wiring in the same conduit

with the high voltage power wiring.

• Some thermostat wire insulation has a voltage rating less

than the line voltage. Route Thermostat Wire behind low voltage shield during unit installation per Figure 2. This is necessary to meet National Electrical Code (NEC) and UL 1995 requirements for separation of high and low voltage circuits.

Conduit for Low Voltage Conductors

Stand Alone with Thermostat

Once Occupied Mode is set to “Control by Thermostat” the DDC Controller will follow the commands from a regular 24VAC thermostat, according to the following convention:

• G - Indoor fan

• Y1 - First stage of compressor

McQuay OM 1077 9

Unit Installation

• Y2 - Second Stage of compressor

• B - Not Used

• W1 - First Stage Auxiliary heat (electric or gas)

• W2 - Second Stage Auxiliary heat (electric or gas)

• L - Comfort Alert signal (output)

• R & C - 24VAC

Figure 3: Thermostat Inputs and Outputs

+24VAC

1st Stage

Compressor

2nd Stage

Compressor

Occupancy Signal

Comfort Alert

Not Used

Indoor Fan

24V Common

2nd Stage Heat

1st Stage Heat

Figure 4: Standalone with Zone Sensor and Time Clock

Standalone with Zone Sensor and Time Clock

If Occupied Mode is set to any of the options other than “Off” and “Control By Thermostat”, the control will operate in Stand Alone mode or network using its local temperature sensors to determine demand. The system can be set up with a zone sensor to determine heat or cool demand and a solid state time clock to determine occupancy . (See Occupied Mode‚ page

17)

Zone Sensor

10k Thermistor

Time Clock

Override

Button

10k Pot

Setpoint Adj.

10 McQuay OM 1077

Unit Installation

Standalone with Building Automation System

If Occupied Mode is set to any of the options other than “Off” and “Control By Thermostat”, the control will operate in Stand Alone mode or network using its local temperature sensors to

Figure 5: Zone Sensor with Building Automation System

determine demand. The system can be set up with a zone sensor, 910108514 or 910108214 communication card, and 2nd party building automation system that will be controlled from a central location.

Zone Sensor

10k Thermistor

Override

Button

10k Pot

Setpoint Adj.

LONWorks Daughter BoardBACnet Daughter Board

McQuay OM 1077 11

Sequence of Operation

Cooling

When the DDC Controller receives a call for cooling via thermostat or zone sensor compressor 1 energizes. After the indoor fan on delay (1-180 sec / default 10 sec) the indoor fan energizes. The indoor fan on delay starts when the call for cooling is initiated.

When used in local zone sensor mode of operation, the DDC Controller satisfies the set point using all or a partial number of stages available. When cooling demand exists, the DDC Controller will stage up in the following order: Economizer, First Stage Cooling, and Second Stage Cooling based on demand.

When used in local thermostat mode of operation, the DDC Controller allows the thermostat to control the demand for cooling. When cooling demand exists, the DDC Controller will stage up in the following order: Economizer, First Stage Cooling. Only two stages will be allowed to energize, so if the economizer is active then the first stage mechanical cooling will become second stage and second stage mechanical cooling will not be used.

Heat

When in heating mode of operation, the DDC Controller satisfies the set point using all or a partial number of stages available. When heating demand exists, the DDC Controller will utilize heat sources in the following order of priority as available: Gas Heat and Electric.

When the heat demand requires multiple heating outputs at the same time, a minimum staging delay of 5 seconds between energizing and de-energizing heating outputs is necessary to prevent the inrush current startup of multiple loads. The inter stage is adjustable between 5 and 50 seconds.

The source of demand, like the other modes of operation, is a result of one of either thermostat or remote sensors.

Integrated Furnace Control

The Integrated Furnace Control (IFC) is external to the DDC Controller, and on units so equipped, controls the furnace and gas valve operation based on signals from the DDC controller. The IFC also provides furnace troubleshooting information via LED flashing fault codes. When a fault condition exists, the LED (see Figure 6) flashes the number of times indicated by the code number, pauses, and repeats.

Figure 6: Integrated Furnace Control Status LED

LED

Table 6: Integrated Furnace Control Fault Codes

Code Meaning

1 Failure To Detect Or Sustain Flame 2 Pressure Switch Or Inducer Problem Detected 3 High Limit Protection Deice Open 4 Gas Valve Not Energized Or No “W” Signal 5 Flame Toll Out Switch Open

Call for Heat

After a call for heat the IFC checks to ensure the high temperature limit and rollout switches are closed. If either is open, the IFC responds with a fault code. If high limit and rollout switches are closed, the IFC checks that both pressure switches are open. If either pressure switch is closed, the IFC will respond with a fault code and it will flash code “2” on the LED, waiting indefinitely for both pressure switches to open. If both pressure switches are open, the IFC proceeds to prepurge.

Pre-Purge

The IFC energizes the low inducer motor, flashes code “2” on LED, and waits for the low pressure switch to close. If the low pressure switch does not close within 3 minutes, the control will energize the high inducer and wait for both pressure switches to close. The IFC will light on high fire and remain on high fire for the remainder of the heat cycle.

When the low pressure switch has closed, the IFC stops flashing the LED and begins timing the 30 second pre-purge period. If flame is sensed as present during pre-purge, the IFC restarts the pre-purge time to require a full pre-purge after flame is removed. When pre-purge time has expired, the IFC begins the ignition trial.

Ignition Trial

The IFC energizes the gas valve and spark. The IFC ignores flame sense for the first 2 seconds of the ignition trial. If flame is not established within 7 seconds, the gas valve and spark is de-energized and the IFC goes to an inter-purge. If flame is established, the spark is de-energized, the IFC energizes the high inducer (low inducer remains energized) and begins heat blower on delay.

12 McQuay OM 1077

Sequence of Operation

Heat Blower On-Delay

The control waits for 45 second heat fan on delay and then energizes the indoor blower heat speed. If the blower is already energized by a call for cooling or continuous fan, or in a blower off delay per iod, t he on dela y is ski pped and t he blower remains energized. After the blower on delay time is complete, the control goes to high fire warm-up mode.

The high pressure switch is ignored during the heat blower on delay to give time for the high pressure switch to close if lighting on low fire.

High-fire Warm-up

The IFC remains on high fire for 120 seconds after flame is established. If the DDC Controller is calling for 2 nd stage heat, the IFC remains in high heat. If the IFC lit on high fire because the low pressure switch did not close within 3 minutes, then th e IFC remains on high fire for the entire call for heat regardless of 2nd stage thermostat call. If there is no DDC Controller demand for 2nd stage heat when the 120 second time has expired, the IFC transitions from high heat to low h eat.

Low Heat

IFC inputs are continuously monitored to ensure limit, rollout, and pressure switches are closed, flame is established, and the thermostat call for heat remains. Low gas, low inducer, and blower remain energized. If the DDC Controller calls for 2nd stage heat (Hi Heat), the IFC transitions to high heat.

High Heat

IFC inputs are continuously monitored to ensure limit, rollout, and pressure switches are closed, flame is established, and the DDC Controller calls for heat remain. Low gas, high gas, low inducer, high inducer, and blower remain energized. If the DDC Controller terminates the call for 2nd stage heat and the first stage call remains, the IFC transitions to low heat.

Low Heat to High Heat Transition

When the DDC Controller calls for 2nd stage heat after low heat is established, the IFC checks the high pressure switch. If the high pressure switch is closed, the IFC flashes “2” on the LED and waits indefinitely for the high pressu re sw itch to open. When the high pressure switch is proven open, the IFC energizes the high inducer motor and waits for the pressure switch to close. If the high pressure switch does not close within 60 seconds, the control flashes “2” on the LED and deenergizes the high inducer motor for 5 minutes. The high inducer is re-energized after the 5 minute period for 60 seconds and the cycle repeats indefinitely until the high pressure switch closes. When the high pressure switch closes, the IFC energizes the high gas output and proceeds to high heat.

High Heat to Low Heat Transition

When the DDC Controller ends the call for 2nd stage heat and the first stage call remains, the IFC de-energizes the high gas output. The high inducer remains energized for 60 seconds after the high gas de-energizes. The IFC proceeds to low heat.

Post Purge

When the DDC Controller demand for heat is satisfied, the IFC immediately de-energizes the gas valve(s). The Inducer output(s) remains on for a 5 second post-purge period. The IFC continues the heat blower off delay.

Heat Blower Off Delay

The IFC de-energizes the Indoor blower motor 90 seconds after the call for heat terminated

Interrupted Call For Heat

If the DDC Controller demand for heat is removed before the ignition period, the IFC will immediately de-energize the inducer.

If the DDC Controller demand for heat is removed after ignition has begun, the induced draft motor will run through a post purge and the indoor blower motor will run on heat speed for the delay off time.

Ignition Retry

If flame is not established on the first trial for ignition period, the induced draft motor remains energized and the IFC deenergizes the low gas valve. The IFC waits for a 60 second inter-purge period then attempts an ignition re-try. If the second ignition trial is unsuccessful, the IFC energizes the high inducer and waits indefinitely for the high pressure switch to close. When the high pressure switch closes, the IFC energizes the high gas output, interpurges 60 seconds and tries the 3rd and 4th ignition attempts on high fire.

If flame is not established on the fourth trial for ignition, the IFC de-energizes the high and low gas outputs and goes into lockout. The IFC indicates a fault by flashing the status LED 1 time to indicate lockout is due to failed ignition.

Ignition Recycle

If flame is established and maintained during the trial for ignition period and then flame is lost, the gas valve is deenergized, the induced draft motor continues to run, and the control begins timing the pre-purge delay. The indoor blower motor will be energized and/or remain energized on heat speed for the delay off time.

When the pre-purge delay is over, the control energizes the spark and gas valve for an ignition attempt. If ignition is unsuccessful, the IFC will attempt up to 3 more retries as described above. The IFC will recycle up to 17 flame losses (16 recycles) within a single call for heat before going to lockout. The IFC status LED will flash 1 time if lockout is due to too many flame loses. (This is same flash code as failed ignition.).

Open Limit switch

The limit switch is ignored unless a call for heat is present. If the limit switch opens while a call for heat is present, the indoor fan is energized on heat speed and both inducers are energized. The gas valve is de-energized if it was energized. The status LED will flash 3 times indicating the Limit switch

McQuay OM 1077 13

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