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McQuay MHC Series, Installation & Maintenance Data, Page: 23 / 36

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McQuay MHC Series Installation & Maintenance Data Download Page 23

IM 985-1 / Page 23 of 36

Typical Wiring Diagrams
MicroTech III Unit Controller with Communication Module and Wall-Mounted Room 

Temperature Sensor 

265/277/60Hz/1-Phase

Note:

 

Wiring diagrams are typical. For the latest drawing version 

refer to the wiring diagram located on the inside of the controls 
access panel of the unit.

Legend
Item 

Description

C1  

Capacitor-Compressor

C2  

Capacitor-Fan

R1  

Relay - Fan Motor

CM 

Compressor - Motor

COS 

Condensate Overflow Sensor

DPG 

Drain Pan Ground

FSR 

Fan Speed Relay

PTB 

Power Terminal Block

HP  

High Pressure Switch

SLTS 

Suction Line Temp Sensor 

OVL 

Compressor Overload Protector

RV  

Reversing Valve Solenoid

T1  

EG2UCP Terminal Strip

X1  

Transformer

LED1 

LED Annunciator / Harness 

CR  

Compressor Relay

LWT 

Leaving Water Temperature Sensor

DAT 

Discharge Air Temperature Sensor

Drawing No. 669542001

When the optional wall-mounted room temperature sen-
sor is connected to the unit controller, the Return Air 
Temperature (RAT) sensor must not be installed. The wall-
mounted room temperature sensor and return air sensor 
must not be connected simultaneously or the unit will not 
operate properly.

     CAUTION

Summary of Contents for MHC Series

Page 1: ...ole Water Source Heat Pumps R 410A Models MHC Standard Range MHW Geothermal Range Flat Top Slope Top Unit Sizes 007 018 Group WSHP Part Number 669544301 Date January 2010 IM 985 1 2010 McQuay Internat...

Page 2: ...ltages 13 Operating Limits 13 14 MicroTech III Unit Controller 14 25 I O Expansion Module 15 MicroTech III Controller with Lon Module 16 MicroTech III Controller with BACnet Module 17 MicroTech III Un...

Page 3: ...nd a report The Warranty Claims Department should then be contacted Do not stand or transport the machines on end For storing each carton is marked with up arrows In the event that elevator transfer m...

Page 4: ...nection end of the subbase and chassis Note Make sure electrical and piping connections are in the proper location within the subbase end piping compartment Unit Installation Recommended Installation...

Page 5: ...in the subbase and secure the subbase to the floor tightening the fasteners Do not over tighten fasteners and distort or warp the subbase plate IMPORTANT 11 Use a carpenters square and level to check...

Page 6: ...It is the responsibility of the installing contractor to provide the appropriate fasteners and anchors to ensure that the unit is secured properly WARNING Left End View Right End View Provided Mounti...

Page 7: ...s supplied with a clear vinyl condensate hose Figure 4 Typical 2 Pipe Reverse Return Configuration Piping 1 Connect units to supply and return piping in a two pipe reverse return configuration Figure...

Page 8: ...ing valves installed in the field between the contractor s piping and the heat pump unit The valve installed on the return line acts as a balancing valve to adjust the proper water flow An automatic f...

Page 9: ...f piping packages Consult your local sales rep for more information Left End Piping View Right End Piping Back View Left End Piping Back View Right End Piping View When installing the hoses on valve a...

Page 10: ...lear vinyl condensate hose internally trapped within the chassis The hose extends 3 89mm out of the chassis within the piping compartment to reach the floor or the back wall Field condensate piping mu...

Page 11: ...ontractor to check for leaks upon start up of the water system could result in property damage Return Runout Supply Runout Mains Flexible Hose Runouts Initially Connected Together 3 Shut off supplemen...

Page 12: ...knockout and remove it Install a strain relief and pass the wires through the strain relief into the junction box making the connection and reinstall the junction box cover Note Check the local code c...

Page 13: ...er Electrical Data General 1 Be sure the available power is the same voltage and phase as that shown on the unit serial plate Line and voltage wiring must be done in accordance with local codes or the...

Page 14: ...t low voltage terminal strip is set up so R G energizes the fan R Y1 energizes the compressor for cooling operation R W1 energizes the compressor and reversing valve for heating operation The reversin...

Page 15: ...eat Shorted to enable reheat JP3 and JP4 open for no supplemental heat JP3 Supplemental JP3 open JP4 shorted for JP4 Heat Type boilerless electric heat JP3 and JP4 shorted is an invalid setting JP5 an...

Page 16: ...vers the installation of a McQuay Console Water Source Heat Pump For installation and operation information on LonWorks Communication Module and other ancillary control components see IM 927 MicroTech...

Page 17: ...available on a communications network using BACnet objects and properties The network cable is a shielded twisted pair cable Network communications run at 76 8 Kbps DIP switches on the controller ena...

Page 18: ...r LED Output TB1 2 2 Fan Mode Heat Cool Auto Input TB1 3 3 Setpoint Adjust Input TB1 4 4 Room Temperature Sensor Tenant Override TB1 5 5 DC Signal Common Test 1 R 24 VAC Test 2 W2 Heat Stage 2 Input T...

Page 19: ...f 36 Figure 15 MicroTech III Unit Controller Terminal Locations Location of Configuration Jumpers on the MicroTech III Unit Controller Note A random start delay time between 180 and 240 seconds is gen...

Page 20: ...Page 20 of 36 IM 985 1 Figure 16 LonWorks Communication Module Placement on MicroTech III Unit Controller...

Page 21: ...atest drawing version refer to the wiring diagram located on the inside of the controls access panel of the unit Legend Item Description C1 Capacitor Compressor C2 Capacitor Fan UMT Unit Mounted Therm...

Page 22: ...n Speed Relay HP High Pressure Switch R2 Relay Electric Heat IOEXP I O Expansion Board Harness LED2 LED Annunciator Harness SLTS Suction Line Temp Sensor OVL Compressor Overload Protector RV Reversing...

Page 23: ...Drain Pan Ground FSR Fan Speed Relay PTB Power Terminal Block HP High Pressure Switch SLTS Suction Line Temp Sensor OVL Compressor Overload Protector RV Reversing Valve Solenoid T1 EG2UCP Terminal Str...

Page 24: ...n LED on a wall thermostat Table 10 shows in which function the fault output is on sending a signal to the LED Units must be checked for water leaks upon initial water system start up Water leaks may...

Page 25: ...ge Heat Cool Systems Single Stage Heat Pump Systems Fan Speed Control Large Display With Backlight Selectable Fahrenheit or Celsius SimpleSet Field Programming Status Indicator Light Relay Outputs min...

Page 26: ...tions C RH RC W Y B O G1 G2 S1 S2 For detailed installation operation and application refer to Operation Application Guide LIAF015 Non Programmable Electronic Thermostat P N 668811001 Non Programmable...

Page 27: ...ew The second part of the T9000 system is called a Remote Control Node or RCN An RCN interfaces with specific desired HVAC equipment and communicates with its thermostat using unlicensed 900 MHz radio...

Page 28: ...e Sensor Terminals Fan Control Slide Switch Mode Control Slide Switch Status LED Green 0 to 10 K ohm Potentiometer Tenant Override Momentary Push Button Switch 4 59 When the optional wall mounted room...

Page 29: ...s version of the board uses VAC relays and should not be used in combination with any other accessories or equipment that require VDC connections to the G W1 or Y1 terminals i e Boilerless System Kit...

Page 30: ...Assembly Manual Outside Damper Assembly Figure 24 Manual Outside Air Damper Assembly See IM 974 for detailed installation instructions Figure 25 Motorized Outside Air Damper Assembly See IM 974 for de...

Page 31: ...tures All McQuay water source heat pumps are designed for commercial use The units are designed for the cooling mode of operation and fail safe to cooling The reversing valve is energized for the heat...

Page 32: ...low Cooling High High High High Low Low High High Pressure High Air Flow Heating Low Low Low Low High Low Low Low Temp High Air Flow Cooling Low High Normal High Low Low Normal High Pressure High Wate...

Page 33: ...refrigerant heat exchanger coil The liquid then evaporates becoming a gas at the same time absorbing heat and cooling the air passing over the surfaces of the coil The refrigerant then flows as a low...

Page 34: ...or lock rotor amp draw Check for defective compressor internal windings with ohm meter Check for proper air flow filter could be dirty Check for low refrigerant charge Check amp draw on blower assembl...

Page 35: ...s powered by the control board s power terminals No solid state devices Triacs may be used to operate the Microtech III unit controller inputs No outside power source may be used to operate the Microt...

Page 36: ...ive go to www mcquay com This document contains the most current product information as of this printing For the most up to date product information please go to www mcquay com Products Manufactured i...

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