Page 3 - Introduction; This manual provides information on the MicroTech II
McQuay OM 751 3 Introduction Introduction This manual provides information on the MicroTech II ® control system used in the AAF ® - HermanNelson ® Unit Ventilator product line. It describes the MicroTech II components, input/ output configurations, field wiring options and requirements, and service ...
Page 4 - NOTICE; interference or for the correction thereof.; WARNING; Extreme temperature can damage system components.; CAUTION
4 McQuay OM 751 Introduction Table 4: Software program literature Description Manual # Air Source Heat Pump with Electric Heat (Software Model 00) OM 748 Water Source Heat Pump with Electric Heat (Software Model 02)Water Source Heat Pump without Electric Heat (Software Model 03) OM 749 DX Cooling wi...
Page 5 - Acronyms/Abbreviations
McQuay OM 751 5 Introduction Acronyms/Abbreviations The following table list acronyms and abbreviations that may or may not be used within this manual. Other abbreviations for keypad displays and parameters can be found in Table 8 on page 14 and Table 26 on page 47. Table 5: Acronyms and abbreviatio...
Page 7 - Getting Started; Display Format; Keypad Functions; Security Levels; Why can’t I use the MODE or FAN key or adjust Set Point Offset?; MicroTech
McQuay OM 751 7 Getting Started Getting Started The MicroTech II Unit Vent Controller (UVC) is a self-contained device that is capable of complete, stand-alone operation. Information in the controller can be displayed and modified by using the keypad/display (local user interface). The following sec...
Page 8 - FAN Key
8 McQuay OM 751 Getting Started Table 6: Keypad/display security levels Figure 2: Changing keypad/display security levels ON/STOP Key and LED Use the ON/STOP key to toggle the UVC between OFF mode and running (Application Mode Input). The ON/STOP LED is off when the UVC is in the OFF mode. Note – Wh...
Page 9 - Viewing Actual Indoor Air Temperature (IAT); Changing Set Points; Menu Reference; The keypad/display menu is accessed via an unmarked,; So; So
McQuay OM 751 9 Getting Started Using the Keypad/Display Viewing Actual Indoor Air Temperature (IAT) Normally, the effective set point temperature appears on the keypad/display. You also can use the keypad/display to view the indoor air temperature (IAT). See Figure 3. Note – When the actual indoor ...
Page 11 - ot
McQuay OM 751 11 Getting Started o5 Exhaust Interlock OAD Min Position set point EOAD Adjust OA damper position above which the exhaust fan output will be energized. There is a fixed –5% differential associated with this set point. RW x 99% o6 Energize Exhaust Fan OAD Set point OADE Adjust OA damper...
Page 12 - Description of Operation; State Programming
12 McQuay OM 751 Description of Operation Description of Operation State Programming The MicroTech II UVC takes advantage of “state” machine programming to define and control unit ventilator operation. “State” defines specific states or modes of operation for each process within the unit ventilator ...
Page 13 - UVC Unit Modes
McQuay OM 751 13 Description of Operation Figure 6: Complete UVC—state diagram UVC Unit Modes The UVC provides several “normal” modes of unit operation. These include: Off, Night Purge, Fan Only, Cool, Emergency Heat, Auto, Heat, and Cool. Normal UVC modes can contain a single state or several state...
Page 17 - Auto Mode; demand controlled ventilation function
McQuay OM 751 17 Description of Operation Auto Mode Auto mode is provided so that the UVC can be set to automatically determine if heating or cooling is required. Auto mode is the default power-up UVC mode. Auto mode is made up of the Heat and Cool modes. When the UVC is set to auto mode, the UVC au...
Page 19 - The UVC monitors the DAT to ensure it does not fall below VCLL.
McQuay OM 751 19 Description of Operation Figure 12: Cool mode super state diagram Econ State (State 3) The Econ state is a “normal” state during Cool mode. The Econ state typically is active in the Cool mode when primary cooling (economizer) is available and adequate to meet the cooling requirement...
Page 21 - Special Purpose Unit Modes
McQuay OM 751 21 Description of Operation The CO 2 demand controlled ventilation function (optional) is active (see “CO2 Demand Controlled Ventilation (optional)” on page 34), and the OA damper is adjusted as needed to maintain the CO 2 set point. Figure 15: Mech state operation (occupied mode and a...
Page 22 - Pressurize Mode
22 McQuay OM 751 Description of Operation In each of these special purpose UVC modes, if the space temperature drops below EHS and the Emergency Heat function is enabled, the UVC is forced into the Emergency Heat mode (see “Emergency Heat Mode (Super State)” on page 16) and then return once the Emer...
Page 23 - Unit Mode Priority
McQuay OM 751 23 Description of Operation Unit Mode Priority The UVC uses the network variables and binary inputs listed in Table 10 and Table 11 to determine the current unit mode. Special purpose UVC unit modes have higher priority than the normal UVC unit modes as shown in the tables. Each table ...
Page 24 - Occupancy Modes; Occupied Mode
24 McQuay OM 751 Description of Operation Occupancy Modes The UVC is provided with four occupancy modes: Occupied, Standby, Unoccupied, and Bypass. The occupancy mode affects which heating and cooling temperature set points are used, affects IAF operation, and affects OAD operation. The Manual Adjus...
Page 25 - Bypass Mode; Additional Occupancy Features; Networked Occupancy Sensor Capability; Remote Wall-Mounted Sensor Tenant Override Switch; Remote Wall-Mounted Sensor Status LED
McQuay OM 751 25 Description of Operation Bypass Mode The bypass mode (also called Tenant Override) is the equivalent of a temporary occupied mode. Once the bypass mode is initiated, it remains in effect for a set period of time (120 minutes, default). During the bypass mode, the UVC uses the occupi...
Page 26 - Space Temperature Set Points; Networked Set Point Capability; Networked Set Point Shift Capability; ) by the corresponding value of the Set Point Shift Input; Networked Space Temperature Sensor Capability
26 McQuay OM 751 Description of Operation Space Temperature Set Points The UVC uses the six occupancy-based temperature set points as the basis to determine the Effective Set point Output. The effective set point is calculated based on the unit mode, the occupancy mode, and the values of several net...
Page 27 - Effective Set Point Calculations
McQuay OM 751 27 Description of Operation Remote Wall-Mounted Sensor with +/–3°FAdjustment (optional) When the optional remote wall-mounted sensor with +/–3°F adjustment dial is used, the UVC effectively writes the value of the set point adjustment dial to the Set Point Offset Input variable. Note –...
Page 29 - Discharge Air Temperature Control
McQuay OM 751 29 Description of Operation Proportional Integral (PI) Control Loops The MicroTech II UVC uses PI-loop control for heating, cooling and ventilation processes within the unit ventilator. Numerous PI algorithms can be used depending upon the unit ventilator configuration. The UVC uses “s...
Page 30 - PI Control Parameters; Proportional Band
30 McQuay OM 751 Description of Operation PI Control Parameters Associated with each PI loop is a set of two adjustable parameters: Proportional Band and Integral Time. When the unit ventilator is properly sized for the space, the factory settings for these parameters provides the best and most robu...
Page 31 - Integral Time; Indoor Air Fan Operation; Area Under The Curve
McQuay OM 751 31 Description of Operation In general, it is best to start with a relatively large proportional band setting (the factory default setting is best) and adjust to smaller values. If you want the system to respond strongly to small changes in the space, adjust the proportional band to a ...
Page 32 - Unoccupied Operation; Outdoor Air Damper Operation; Put a relay across the Triac outputs.; Minimum Position; Economizer Operation; The UVC supports three economizer functions:
32 McQuay OM 751 Description of Operation Unoccupied Operation During unoccupied mode, the IA fan typically remains off and cycles with calls for heating and cooling. Cycle Fan The UVC is provided with a Fan Cycling Configuration variable that can be used to force the IA fan to cycle with calls for ...
Page 33 - Temperature Comparison Economizer (default)
McQuay OM 751 33 Description of Operation • Expanded (optional)—Temperature Comparison with OA Enthalpy Setpoint Economizer (Strategy 1) • Leading Edge (optional)—Temperature Comparison with Enthalpy Comparison Economizer (Strategy 2) Temperature Comparison Economizer (default) If the default Basic ...
Page 35 - ASHRAE Cycle II; DCV control or reduced to; Compressor Operation; Compressor Envelope; Compressor Cooling Lockout
McQuay OM 751 35 Description of Operation ASHRAE Cycle II The UVC supports ASHRAE Cycle II operation. The basis of ASHRAE Cycle II is to maintain the required minimum amount of ventilation whenever possible, which can be increased during normal operation for economizer cooling or CO 2 DCV control or...
Page 36 - Compressor Minimum On and Off Timers; Outdoor Air Fan Operation
36 McQuay OM 751 Description of Operation Compressor Minimum On and Off Timers The UVC is provided with minimum On (3-minute default) and minimum Off (5-minute default) timers to prevent adverse compressor cycling. Compressor Start Delay The UVC is provided with a Compressor Start Delay configuratio...
Page 37 - External Binary Inputs; External Binary Input 1; Unoccupied Input Signal; External Binary Input 2; This input can only be used for remote shutdown.; Remote Shutdown Input Signal; External Binary Input 3; Ventilation Lockout Input Signal; Binary Inputs; sets of dry contacts to signal UVC
McQuay OM 751 37 Description of Operation External Binary Inputs The UVC is provided with three binary inputs that provide the functions described below. Figure 24: Binary inputs These inputs each allow a single set of dry contacts to be used as a signal to the UVC. Multiple units can be connected t...
Page 38 - Exhaust Interlock Input Signal; External Binary Outputs; External Binary Output 1; This output can only be used as a signal for space lights.; External Binary Output 2; This output can only be used as a fault signal.; Fault Signal; External Binary Output 3; Binary Outputs; relay type outputs w/signal voltage
38 McQuay OM 751 Description of Operation Exhaust Interlock Input Signal This input allows a single set of dry contacts to be used to signal the UVC that an exhaust fan within the space is energized. The UVC repositions the OA damper to a user adjustable minimum position (Exhaust Interlock OA Damper...
Page 39 - Exhaust Fan ON/OFF Signal
McQuay OM 751 39 Description of Operation Exhaust Fan ON/OFF Signal This relay output provides one set of Normally Open dry contacts that can be used to signal the operation of an exhaust fan. When the OA damper opens more than the Energize Exhaust Fan OA Damper set point, then the relay output sign...
Page 40 - UVC Input and Output Table
40 McQuay OM 751 UVC Input and Output Table UVC Input and Output Table All UVC input and output connections and their corresponding unit ventilator usage are shown in the following table. Table 21: Inputs and outputs, software model 05—DX cooling only I/O Description BO-1 Inside Fan HighBO-2 Inside ...
Page 41 - Diagnostics and Service; The problem resides within the UVC.; Alarm and Fault Monitoring; The fault signal binary output energizes.
McQuay OM 751 41 Diagnostics and Service Diagnostics and Service The most important aspect of troubleshooting unit ventilator controls is to isolate the source of the problem into one of two categories: 1 The problem resides within the UVC. 2 The problem is external to the UVC. Under most circumstan...
Page 42 - Space Temp Sensor Failure (; Outside air damper is forced closed.; Compressor Envelope Fault (
42 McQuay OM 751 Diagnostics and Service Space Temp Sensor Failure ( F0 ) The Space Temp Sensor Failure fault occurs when the UVC detects open or short conditions from the sensor. Effect: • Space fan de-energizes (unless in emergency heat mode). • Compressor immediately de-energizes. • Outdoor fan (...
Page 43 - Space Coil DX Temp Sensor Failure (; Discharge Air Temp Sensor Failure (; Outdoor Coil DX Temp Sensor Failure (
McQuay OM 751 43 Diagnostics and Service Condensate Overflow Indication (optional) ( F4 ) The Condensate Overflow Indication fault will occur when the UVC detects high condensate levels within the units indoor coil drain pan. Effect: • Compressor is immediately de-energized if in cooling. • Outdoor ...
Page 44 - Fb; Space CO; FC; The Space CO; Change Filter Indication (; FF; EPROM Memory Indicator (; EE; Configuration Display (; Troubleshooting Temperature Sensors; Use the following procedure to troubleshoot a suspect sensor.
44 McQuay OM 751 Diagnostics and Service Space Humidity Sensor Failure (optional) ( FA ) The Space Humidity Sensor Failure fault occurs when the UVC detects open or short conditions from the sensor. Effect: • IA/OA Enthalpy comparison economizer (if used) is disabled. • Dehumidification function (op...
Page 45 - Troubleshooting Humidity Sensors; Use the following procedure to troubleshoot a suspect sensor:
McQuay OM 751 45 Diagnostics and Service 3 Use the temperature reading from Step 2 to determine the expected sensor resistance from Table 23. 4 Using a calibrated ohmmeter, measure the actual resistance across the two sensor leads. 5 Compare the expected resistance to the actual resistance. 6 If the...
Page 46 - Troubleshooting Carbon Dioxide (CO
46 McQuay OM 751 Diagnostics and Service Table 24: Humidity versus voltage. Troubleshooting Carbon Dioxide (CO 2 ) Sensors The UVC is configured to use a 0–2000 PPM, 0–10 VDC, single beam absorption infrared gas sensor. Each sensor is calibrated according to the table shown. Use the following proced...
Page 47 - UVC Configuration Parameters; Co
McQuay OM 751 47 UVC Configuration Parameters UVC Configuration Parameters The UVC is been provided with a number of configuration variables as listed in the following table. These configuration variables are stored in UVC non-volatile memory. For a description of supported network variables for eac...
Page 48 - CF
48 McQuay OM 751 UVC Configuration Parameters Primary Cool Proportional Band 18°F (10°C) Primary Cool Integral Time 180 sec Secondary Cool Proportional Band 18°F (10°C) Secondary Cool Integral Time 600 sec Discharge Air Temp Proportional Band 4°F (2.22°C) Discharge Air Temp Integral Time 300 sec CO ...
Page 50 - McQuay Training and Development; Warranty
© 2006 McQuay International • www.mcquay.com • 800-432-1342 McQuay Training and Development Now that you have made an investment in modern, efficient McQuay equipment, its care should be a high priority. For training information on all McQuay HVAC products, please visit us at www.mcquay.com and clic...
