Orion MHGRV II User Manual
MHGRV II Controller
Technical Guide
Table Of Contents
Controller Overview ......................................................................................................................................... 3
General.........................................................................................................................................................................................3
Features .......................................................................................................................................................................................3
Operation......................................................................................................................................................................................3
Controller Inputs and Outputs ......................................................................................................................... 4
General.........................................................................................................................................................................................4
Analog Inputs ...............................................................................................................................................................................4
24 VAC Contact Closure Inputs: ...................................................................................................................................................4
Controller Installation & Wiring ...................................................................................................................... 4
Controller Mounting ...................................................................................................................................................................... 4
Relay Outputs...............................................................................................................................................................................4
Modulating HGR Valve Outputs ...................................................................................................................................................4
Important Wiring Considerations .................................................................................................................................................. 4
DIP Switch Settings ......................................................................................................................................... 7
Supply Air Temperature ................................................................................................................................................................ 7
Supply Air Temperature Reset Limit ............................................................................................................................................7
Start-up & Commissioning............................................................................................................................... 8
General.........................................................................................................................................................................................8
Power Wiring ............................................................................................................................................................................... 8
Power Up And Operation..............................................................................................................................................................8
Programming The Controller ........................................................................................................................................................8
Sequence Of Operation ................................................................................................................................... 9
Initialization...................................................................................................................................................................................9
Modulating Hot Gas Valves ..........................................................................................................................................................9
Modes Of Operation ..................................................................................................................................................................... 9
Additional Features ......................................................................................................................................................................9
Troubleshooting ............................................................................................................................................. 10
Using LED’s To Verify Operation ................................................................................................................................................ 10
Other Checks .............................................................................................................................................................................10
WattMaster Controls Inc.
8500 NW River Park Drive · Parkville , MO 64152
Toll Free Phone: 866-918-1100
PH: (816) 505-1100 · FAX: (816) 505-1101 · E-mail: mail@wattmaster.com
Visit our web site at www.orioncontrols.com
AAON® Part No.: R12200
WattMaster Form: AA-MHGRVII-TGD-01E
Copyright September 2011 WattMaster Controls, Inc.
AAON is a registered trademark of AAON, Inc., Tulsa, OK.
WattMaster Controls, Inc. assumes no responsibility for errors, or omissions.
This document is subject to change without notice.
Controller Overview
Technical Guide
General
The MHGRV II Controller is designed to control a Modulating Hot
Gas Reheat Valve to maintain a desired Supply Air Temperature and
Humidifi cation setpoint . The controller can be used as a stand-alone
controller or it can be connected to and used in conjunction with the
AAON Factory Packaged HVAC unit controller. The MHGRV II controller is connected to the HVAC unit controller via a modular expansion
cable and corresponding connectors on the controllers.
Features
The MHGRV II provides the following features.
Can Be Operated as a Stand-Alone Controller or Integrated
with the HVAC Unit Controller
Provides for Supply Air Temperature Setpoint
Reset when Required
Second Stage Reheat Capability When Using
2 Hot Gas Reheat Valves
Control of Reheat Solenoid Valve to
Provide Coil Flushing for Positive Refrigerant Oil
Return
Operation
When used in a stand-alone application (not connected to an HVAC unit
controller board) the MHGRV II controller will control the Modulating
Hot Gas Valve to maintain the Supply Air Setpoint based on the Supply
Air Temperature Sensor connected to the MHGRV II controller. The
MHGRV II controller is activated by a 24 VAC wet contact closure
signal connected to the H1 (RHT EN) input terminal on the controller.
Heating Override and Cooling Override are also controlled by 24 VAC
wet contact closure signals connected to the HTG OVR and CLG OVR
input terminals on the controller. The Supply Air Setpoint is set by
confi guring a DIP switch on the MHGRV II controller board. Supply
Air Temperature Reset is also available and is set by confi guring a DIP
switch on the controller board. When Supply Air Temperature Reset is
used it is reset by a 0-10 VDC signal supplied to the RST IN terminal
on the MHGRV II controller.
When the MHGRV II controller is connected to an HVAC unit controller board via its modular cable it will operate exactly as the stand-alone
controller except the following information will be passed between the
MHGRV II controller and the HVAC unit controller.
Reheat Enable command
Supply Air Temperature Setpoint. This replaces the
setpoint that is set with the Supply Air Temperature DIP
switch on the MHGRV II controller.
The Reset Supply Air Temperature Setpoint. This replaces
the setpoint that is set with the Supply Air Temperature
Reset DIP switch on the MHGRV II controller. The Supply
Air Temperature Reset Signal is also supplied from the
HVAC unit controller.
If the communication is interrupted between the MHGRV
II controller and the HVAC unit controller, the
MHGRV II controller will revert to stand-alone operation.
TB3
SHLD
R
COMM
VR1
T
R12
PU
D2
R4
RV1
R2
C3
CX1
C1
X1
YS101818P552
PROCESSOR
BOARD
4.80"
PJ1
C1
2
ICIN
D1
R18
L1
R19
C8
L2
V5
R31
D11
R38
+24VAC
2
ICOUT
C3
U2
GND
C13
TB4
R11
D5
D6
R3
R1
R3
R20
WDOG
C12
CX6
U6
U1
D1
D1
C2
C4
P1
Figure 1: MHGRV II Controller Dimensions
8.10"
FAN
CW/HW
CB/HB
CR/HG
EPROM
STEP
U3
CG/HR
R2
R17
COMP
VALV E
AUX
R23
CX5
STATUS
POWER
K1
K2
K3
K4
R39
CLG OVR
GND
SAT
R1
1
HTG OVR
R5R6D4
U2
CX5
RST IN
RHT IN
R13
R7
D3
CX2
U5
R8
AUX IN
AUX IN
SETUP
R9
RAM
CX4
GND
GND
THERM
4-20MA
0-10V
C2
+VDC
U1
C4
U4
CX3
U5
RESET LIMIT
SETPOINT
R40
128
64
32
1286416
32
SW1
16
SW2
V1
V2
V3
V4
8
8
FAN
COMP
VALV E
AUX
COM
421
4
C15
YS101894 REV 1
HOT GAS REHEAT
SERIAL #
TB5
4.69"
ADD
ADD
1
2
8.01"
VAV/Zone Controller 3
Technical Guide
Controller Inputs and Outputs
General
The following inputs and outputs are available on the MHGRV II controller For component locations of the inputs, outputs and wiring, see
Figure 3 and 4.
Analog Inputs
SAT: Supply Air Temperature Sensor
The Supply Air Temperature Sensor is the main control input. This sensor
has to be installed for the unit to operate. The Supply Air Temperature
Sensor is located in the discharge air stream and monitors the HVAC
units Supply Air Temperature to maintain the Supply Air Temperature
Setpoint.
RST IN: Reset Signal
The Discharge Temperature Setpoint can be reset by supplying a 0-10
VDC signal to the RST IN low voltage terminal block. This reset signal
is optional and need only be used if you require resetting of the discharge
air temperature.
AUX IN: Not Used
24 VAC Contact Closure Inputs:
RHT EN: Dehumidifi cation
When a call for dehumidifi cation is initiated by another controller this
interlocked 24 VAC wet contact closure is used to enable the MHGRV
II controller.
HTG OVR: Heating Override
When a call for heating is initiated by the HVAC unit, this interlocked
24 VAC wet contact closure is used to override the MHGRV II controller
dehumidifi cation mode.
CLG OVR: Cooling Override
When a call for cooling is initiated by the HVAC unit, this interlocked
24 VAC wet contact closure is used to override the MHGRV II controller
dehumidifi cation mode.
Relay Outputs
FAN: Fan Enable
When a call for Dehumidifi cation, Cooling Override or Heating Over-
ride is received, this relay output will be closed to energize the HVAC
unit Supply Fan.
COMP: Compressor Enable
When a call for Dehumidifi cation or Cooling Override is received this
relay output will be closed to energize the Compressor(s).
VALVE: Reheat Solenoid Valve
When a call for Dehumidifi cation is received and reheat is required this
relay output will be closed to energize the Hot Gas Solenoid Valve approximately 30 seconds after the Fan and Compressor have been enabled.
AUX: 2 Position HGR Valve
Used on larger capacity systems that have an optional 2 Position HGR
Valve in addition to the Modulating HGR Valve. When a call for Dehumidifi cation is received and additional reheat is required beyond the
Modulating HGR valves capacity, this relay output will be closed to
energize the 2 Position HGR Valve, while the Reheat Solenoid Valve
continues to modulate as required. This AUX (2 Position HGR Valve)
Relay will energize when the Modulating HGR Valve stays at 100% for 1
½ minutes. The AUX Relay will de-energize when the Modulating HGR
Valve stays at 0% for 1½ minutes. The AUX Relay is not be energized
during the Dehumidifi cation Reheat Coil Flush Cycle.
Modulating HGR Valve Outputs
CG/HR:
This output is connected to the Condensor HGR Valve Green Wire
Termination and to the Reheat HGR Valve Red Wire Termination to
control their modulation.
CR/HG:
This output is connected to the Condensor HGR Valve Red Wire Termination and to the Reheat HGR Valve Green Wire Termination to control
their modulation.
CW/HW:
This output is connected to the Condensor HGR Valve White Wire
Termination and to the Reheat HGR Valve White Wire Termination to
control their modulation.
CB/HB:
This output is connected to the Condensor HGR Valve Black Wire
Termination and to the Reheat HGR Valve Black Wire Termination to
control their modulation.
Controller Installation & Wiring
Controller Mounting
It is important to mount the controller in a location that is free from
extreme high or low temperatures, moisture, dust and dirt.
Be careful not to damage the electronic components when mounting
the controller. Remove the controller from its snap track mount. Mark
the control enclosure base using the snap track as a template. Drill pilot
holes in the enclosure base and secure the snap track to it using sheet
metal screws. Do not allow metal shavings to fall onto the circuit board.
Reattach the controller to the snap track.
4
Important Wiring Considerations
Depending on if the MHGRV II controller is to be connected to the
HVAC controller or is to be used as a stand-alone controller determines
how the MHGRV II should be wired. For the stand-alone wiring diagram, see Figure 2. For the wiring diagram to use when the MHGRV
II controller is connected to an HVAC controller, see Figure 3. Please
carefully read and apply the following information when wiring the
MHGRV II controller.
MHGRVII Controller
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