Orion MHGRV III User Manual
MHGRV III Controller
Technical Guide
Table of Contents
Controller Overview ......................................................................................................................................... 3
General.........................................................................................................................................................................................3
Features .......................................................................................................................................................................................3
Operation......................................................................................................................................................................................3
Inputs and Outputs .......................................................................................................................................... 4
General.........................................................................................................................................................................................4
Analog Inputs ............................................................................................................................................................................... 4
24 VAC Contact Closure Inputs ....................................................................................................................................................4
Analog Outputs.............................................................................................................................................................................4
Relay Outputs...............................................................................................................................................................................4
Modulating HGR Valve Outputs ...................................................................................................................................................4
Installation & Wiring ........................................................................................................................................ 5
Controller Mounting ...................................................................................................................................................................... 5
Important Wiring Considerations .................................................................................................................................................. 5
Additional Modulating Hot Gas Valve Control ..............................................................................................................................5
MGHRV III Controller Master To Slave Wiring when Used with VCM Controller .........................................................................6
MGHRV III Controller Master To Slave Wiring when Used with VCM-X Controller ...................................................................... 8
MGHRV III Controller Master To Slave Stand Alone Wiring .......................................................................................................10
DIP Switch Settings ....................................................................................................................................... 12
Supply Air Temperature .............................................................................................................................................................. 12
Supply Air Temperature Reset Limit ..........................................................................................................................................12
Field Testing ...............................................................................................................................................................................13
Start-up & Commissioning............................................................................................................................. 14
General.......................................................................................................................................................................................14
Power Wiring ............................................................................................................................................................................. 14
Power Up and Operation ............................................................................................................................................................14
Programming the Controller .......................................................................................................................................................14
Sequence of Operation .................................................................................................................................. 15
Initialization.................................................................................................................................................................................15
Modulating Hot Gas Valves ........................................................................................................................................................15
Modes of Operation ....................................................................................................................................................................15
Additional Features .................................................................................................................................................................... 15
Troubleshooting ............................................................................................................................................. 16
Using LEDs to Verify Operation..................................................................................................................................................16
Other Checks ............................................................................................................................................................................. 16
2425 So. Yukon Ave • Tulsa, OK • 74107-2728
Ph: (918) 583-2266 • Fax: (918) 583-6094
WM Form: AA-MHGRVIII-TGD-01D
Printed in the USA • Copyright 2010 • All Rights Reserved • March 2011Watt-
Master Controls, Inc. • 8500 NW River Park Drive • Parkville, MO 64152
AAON® Part No.: R76540
WattMaster Controls, Inc. assumes no responsibility for errors or omissions.
AAON® is a registered trademark of AAON, Inc., Tulsa, OK.
This document is subject to change without notice.
MHGRV III Controller Technical Guide
Controller Overview
General
The MHGRV III 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 con-
troller or it can be connected to and used in conjunction with the AAON
Factory Packaged HVAC unit controller. The MHGRV III controller is
connected to the HVAC unit controller via a modular expansion cable
and corresponding connectors on the controllers.
Features
The MHGRV III provides the following:
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
fl ushing for positive refrigerant oil return
Expansion capabilities for controlling additional
modulating hotgas values
Operation
When used in a stand-alone application (not connected to an HVAC unit
controller board), the MHGRV III 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 III controller. The
MHGRV III 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 HEAT OVR and COOL
OVR input terminals on the controller. The Supply Air Setpoint is set
by confi guring a DIP switch on the MHGRV III controller board. Sup-
ply 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 RESET
IN terminal on the MHGRV III controller.
When the MHGRV III controller is connected to an HVAC unit controller board via its modular cable, it will operate exactly as the stand-alone
controller except that the following information will be passed between
the MHGRV III 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 III 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 III controller. The Supply
Air Temperature Reset Signal is also supplied from the
HVAC unit controller.
If the communication is interrupted between the MHGRV
III controller and the HVAC unit controller, the
MHGRV III controller will revert to stand-alone operation.
0.30
7.40
1248163264
1002
R45
1
ADD ADD
1002
R28
P4
CHASSISGND
C16
128
OFF
1002
1002
1002
1002
1002
1002
1002
R52
R51
R50
R49
R48
R47
R46
128643216842
OFF
1002
1002
1002
1002
1002
1002
1002
R34
R33
R32
R31
R35
R30
R29
2211
2211
2211
2211
R44R43
R42R41
R57R56
R55R54
2211
2211
2211
2211
COM
AUX
D11
VALVE
CMP
D8
FAN
D7
TB2
.1uF
C31
R73
R72
LM358
1001
1001
TB6
1002
10uF
.01uF
GND
AOUT
C33
C18
.1uF
U14
74HC541
SW2
C21
.1uF
U13
74HC541
RESET LIMIT SETPOINT
SW1
TPIC6B259
.1uF
C13
U11
10A250VAC~
5A30VDC
V4
VDE
SA
10A250VAC~
5A30VDC
V3
VDE
SA
10A250VAC~
5A30VDC
V2
VDE
SA
10A250VAC~
5A30VDC
V1
VDE
SA
C3
.1uF
C6
.1uF
SF000140
U19
R69
R78
1002
U12
R76
4751
R77
4751
R74
4751
0404
R75
4751
U20
.1uF
CHINA
DC24V
G5Q-1A4
OMRON
K4
CHINA
L293DNE
NE5090
DC24V
G5Q-1A4
OMRON
K3
CHINA
C24
.1uF
DC24V
G5Q-1A4
OMRON
K2
CG/HR
CR/HG
CHINA
DC24V
G5Q-1A4
OMRON
K1
U8
C2
.1uF
C36
.1uF
CY62256LL
74HC573
U4
U2
EPROM
R60
R62
36503650
D13
D12
STATSTEP
J2
10uF
0-5V
C25
U16
1002
0-10V
1002
4-20
2500
THERM
1002
R53
AUXIN
VAVLE EXP
TB4
GND
GND
+VDC
CW/HW
CB/HB
SF000093a
U15
X2VR1
C22
C26
R59
R38
R58
4751
R61
R37
3001
R36
4751
R27
3001
R26
4751
D10
3001
R25
R40
R39
10uF
C20
1002
1002
AUX IN
RHT EN
RESET IN
.1uF
C23
VREF
11.059Mhz
C27
22pF 22pF
R12
PS2815-4
C19
10uF
R24
1002
C17
10uF
R23
1002
C15
10uF
U22
R22
1002
D3
C14
.1uF
COOL OVR
GND
HEAT OVR
R63
SERIAL#
D14
YS102138REV 3
WATTMASTERCONTROLS
HOT GAS REHEATIII
R8
1002
R7
1002
R6
1002
R5
1002
R4
1002
R3
1002
R2
1002
R1
1002
10uF10uF
C8
R11
3011
U23
04 04
R19
D2
3650
R10
04
4751
REC
U5
U21
DRV
R21
R20
LT1785
485
.1uF
1002
1002
TB3
T
SAT
SH
R
U10
3650
C4
R9
WDOG
R16
C11
C9
TB1
POWER
C5
22pF 22pF
11.059Mhz
PHILIPS
C1
10020
R79
4751
.1uF
R13
7500
C7
93C46
.1uF
U6
DFD9940SM
500650=1/3
PCB80C552-5-16WP
PHILIPS
U1
P82B96
U9
.1uF
C12
D1
R18
R17
R14
10
10
7500
WARNING
OBSERVE
TB5
POLARITY
GND
D16
24VAC
R70
R71
V5
34063
1211
3831
.22
C35
U18
100pF
1N5819
D17
U7
C34
L2
U17
R66
R65
34063
.22
1741
1502
R64
C30
100pF
1N5819
C10
C29
D15
.1uF
4751
R15
L1
P2 P1
0.30
4.10
C28
RS1G
D5
4.70
4.92
8.00
8.15
Figure 1: MHGRV III Controller Dimensions
Operator Interface 3
MHGRV III Controller Technical Guide
Inputs and Outputs
General
The following inputs and outputs are available on the MHGRV III
controller For component locations of the inputs, outputs and wiring,
see Figures 2 and 3.
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
unit’s Supply Air Temperature to maintain the Supply Air Temperature
Setpoint.
RESET IN: Reset Signal
The Discharge Temperature Setpoint can be reset by supplying a 0-10
VDC signal to the RESET 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: Valve Force Position Signal
The modulating HGR valves can be forced to a fi xed position by supply-
ing a 0-10 VDC signal to the AUX IN input. The setpoint and reset limit
switches must both be set to 1 to enable the valve force to work.
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
III controller.
HEAT 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 III controller
dehumidifi cation mode.
COOL 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 III controller
dehumidifi cation mode.
Analog Outputs
AOUT 1: Valve Position Signal
The valve position signal is a 0-10 VDC signal that matches the position
of the valve. 0V = 0%, 10V = 100%.
Relay Outputs
COM: Relay Common
Requires 24 VAC from transformer.
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.
CMP: 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 active for 30 seconds, this relay
output will be closed to energize the Hot Gas Solenoid Valve.
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 the modulating HGR valve is at 100%, this
relay output will be closed to energize the 2 Position HGR Valve. The
relay will open when the modulating HGR valve is at 0%.
Modulating HGR Valve Outputs
CG/HR:
This output is connected to the Condenser 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 Condenser 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 Condenser 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 Condenser HGR Valve Black Wire
Termination and to the Reheat HGR Valve Black Wire Termination to
control their modulation.
4
Operator Interface
MHGRV III Controller Technical Guide
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.
General Wiring Information
Please carefully read and apply the following information when wiring
the MHGRV III controller.
1. All 24 VAC wiring must be connected so that all ground
wires remain common. Failure to follow this procedure
can result in damage to the controller and connected
devices.
2. All wiring is to be in accordance with local and national
electrical codes and specifi cations.
3. Minimum wire size for 24 VAC wiring should be 18 gauge.
4. Minimum wire size for all sensors should be 24 gauge.
5. Be sure that all wiring connections are properly inserted and
tightened into the terminal blocks. Do not allow wire
strands to stick out and touch adjoining terminals which
could potentially cause a short circuit.
Important Wiring Considerations
Depending on if the MHGRV III controller is to be connected to the
HVAC controller or is to be used as a stand-alone controller determines
how the MHGRV III should be wired. For the wiring diagram to use
when the MHGRV III controller is connected to a VCM controller, see
Figure 2. For the wiring diagram to use when the MHGRV III controller
is connected to a VCM-X controller, see Figure 3. For the stand-alone
wiring diagram, see Figure 4. Please carefully read and apply the following information when wiring the MHGRV III controller.
Additional Modulating Hot Gas Valve
Control
HGR Valve Slave Board
This board is connected to the MHGRV III board with a cable that plugs
into the connector labeled Valve Exp. This board provides control to an
additional set of modulating valves. The position of the valves will be
the same as the board they are plugged into.
MHGRV III Slave Board Confi guration
Whenever the MHGRV III has both its setpoint switches set to 1, it will
work as a slave board. The board is active when it has a 24 VAC signal
on the RHT EN input. When the board is active, it looks for a 0-10
VDC on the AUX IN input and moves the HGR valves accordingly.
For example, if the input is at 10 VDC, then the reheat valve would be
100% open. If the voltage is at 5 VDC, the reheat valve would be 50%
open. See Figures 3 and 4.
Operator Interface
5
MHGRV III Controller Technical Guide
Installation & Wiring
Figure 2: MHGRV III Controller Master To Slave Wiring When Used With VCM Controller (R46170)
6
Operator Interface
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