Orion MHGRV-X User Manual

Factory Packaged Controls

MHGRV-X Controller

Field Technical Guide

TABLE OF CONTENTS
CONTROLLER OVERVIEW...............................................................................................................		3
Features...................................................................................................................................................................		3
INSTALLATION & WIRING...............................................................................................................		4
Important Wiring Considerations..............................................................................................................................		4
MHGRV-X Controller to AAON Unit Controller Wiring..............................................................................................		5
MHGRV-X Stand Alone Wiring.................................................................................................................................		6
INPUTS AND OUTPUTS ..................................................................................................................		7
OPERATION OVERVIEW ..................................................................................................................		8
Initialization ..............................................................................................................................................................		8
Modulating Hot Gas Valves......................................................................................................................................		8
Modes of Operation .................................................................................................................................................		8
Additional Features ..................................................................................................................................................		8
LCD DISPLAY SCREENS..................................................................................................................		9
TROUBLESHOOTING.....................................................................................................................		13
Using LEDs to Verify Operation .............................................................................................................................		13
Temperature Sensor Testing ........................................................................................................................................		14
APPENDIX A - Supply Air Temperature Sensor Guide	.................................................................	17
Supply Air Temperature Sensor Installation ...........................................................................................................		17
Supply Air Temperature Sensor Wiring Chart and Jumper Settings ......................................................................		18
APPENDIX B ..................................................................................................................................		19
MHGRV-X Replacement of MHGRV II...................................................................................................................		19
APPENDIX C ..................................................................................................................................		20
Reheat Expansion Module.....................................................................................................................................		20
PART NUMBER CROSS REFERENCE TABLE
PART DESCRIPTION		AAON
	ORION
		TULSA
MHGRV-X Controller	OE377-26-00059	V12100
Reheat Expansion Module	OE377-01-00059	V42450
MODGAS-X Controller	OE377-26-00058	V12090
Supply Air Temperature Sensor	OE231	P87140
EBC E-BUS Cables - Varying Lengths	EBC-XXX-F	N/A

		www.aaon.com
	WattMaster Controls Inc.	WattMaster Form: AA-MHGRVX-FIELD-TGD-01H
	8500 NW River Park Drive · Parkville, MO 64152	Copyright April 2015 WattMaster Controls, Inc.
	Toll Free Phone: [phone]	AAON® Manual Part No.: V16950
	PH: [phone] · FAX: [phone]	AAON® is a registered trademark of AAON, Inc., Tulsa, OK.
	E-mail: [e-mail]	Neither WattMaster Controls, Inc. nor AAON® assumes any
	Visit our web site at www.orioncontrols.com	responsibility for errors or omissions in this document.
		This document is subject to change without notice.

2	MHGRV-X Field Technical Guide

OVERVIEW

MHGRV-X Controller General Information

Overview	Features

The OE377-26-00059 MHGRV-X Controller (AAON Part No. V12100) is designed to control a Modulating Hot Gas Reheat Valve to maintain a desired Supply Air Temperature setpoint. The controller can be used as a stand-alone controller or can be used in conjunction with any AAON unit controller.

In addition, up to (7) Reheat Expansion Modules can be connected to the Controller and to each other for additional Reheat Valve Control.

The MHGRV-X controller connects to an AAON unit controller or expansion module via a modular cable. Depending on the type of unit controller, this connection will utilize an I2C connection or an E-BUS connection.

When using the MHGRV-X Controller to replace an existing MHGRV II Controller, see Appendix B, page 19 for details.

See Figure 1 for dimensions (in inches).

The MHGRV-X provides the following:

Can be operated as a stand-alone controller or communicating with AAON unit controllers.

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

Can provide further Reheat control using up to (7) Reheat Expansion Modules

Contains a 2 x 8 LCD character display and 4 buttons that allow for status display, setpoint changes, and configuration changes

5.73
5.24
2.62
5.04	5.63
0.21
2.04
0.57	Note: Depth is 1.49 inches.
4.09
Figure 1: OE377-26-00059 MHGRV-X Controller Dimensions

MHGRV-X Field Technical Guide

3

WIRING

Installation & Wiring

Installation & Mounting

The MHGRV-X Controller is housed in a plastic enclosure. It is designed to be mounted by using the 3 mounting holes in the enclosure base. It is important to mount the module 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 module.

NOTE: The MHGRV-X Controller contains no user-serviceable parts. Contact qualified technical personnel if your Controller or Module is not operating correctly.

General Wiring Information

Depending on if the MHGRV-X Controller is to be connected to the HVAC controller or is to be used as a stand-alone controller determines how the MHGRV-X should be wired. For the wiring diagram to use when the MHGRV-X Controller is connected to an AAON Unit Controller, see Figure 2, page 5. For the stand-alone wiring diagram, see Figure 3, page 6.

For Reheat Expansion Module wiring, see Figure 9, page 22.

Please carefully read and apply the following information when wiring the MHGRV-X controller and its expansion board(s):

1.18 gauge minimum wire unless otherwise noted.

2.24 VAC power connection with an appropriate VA rating.

3.Supply Air Temperature Sensor and Heat Enable must have 24 gauge minimum wire.

4.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 module and connected devices.

5.All wiring is to be in accordance with local and national electrical codes and specifications.

6.Check all wiring leads at the terminal block for tightness. Be sure that wire strands do not stick out and touch adjacent terminals. Confirm that all transducers required for your system are mounted in the appropriate location and wired into the correct terminals.

4	MHGRV-X Field Technical Guide

WIRING

MHGRV-X to AAON Unit Controller Wiring

Communications Wiring

For connection to a VCB-X Controller, VCB-X Expansion Module, and Reheat Expansion Module, use an E-BUS Cable to connect to the appropriate E-BUS port on those modules and/or controller.

For all other controllers, including the VAV/CAV, MUA,VCM, VCM-X, SA, and RNE Controllers, use an I2C Cable connecting to the appropriate I2C ports on those controllers.

When connected to an AAON Unit Controller, the Supply Air Temperature Sensor is attached to the Main Controller. See Figure 2 below.

See the SAT Wiring Conditions Table and SAT OPTIONS jumper settings in Tables 7 & 9, page 18.

	MHGRV-X CONTROLLER
	(OE377-26-00059)
Connect Supply Air Temperature
Sensor To AI2 & GND		Fan
On Main Controller		C1
(This Does Not Apply To
		Compressor
CAV/VAV Or MUA Applications)
		C2
		HGR Solenoid Valve
Supply
Air Temperature
Sensor
		2 Position HGR Valve (Optional)
Mount In Supply		COMM
Air Duct
See Table 9 On Page 18		Condenser Valve #1
For SAT OPTIONS		BLK
Jumper Settings.
		WHT
Only One Supply Air
		RED
Temperature Sensor Can Be
Used Per Application.		GRN
		BLK
		WHT
		GRN
		RED
I2C Cable		HGR Valve #1
Connects To
I2C Port On		24VAC
Any Non VCB-X Controller Or	GND
Expansion Module

	EBC E-BUS Cable	EBC
		E-BUS	40 VA
	Connects To
		Cable	Transformer
	VCB-X Expansion
		Connects	Minimum
	Port When Used
		To Reheat
	With VCB-X
		Expansion
	Controller		Line
		Module

Figure 2: MHGRV-X Controller to AAON Unit Controller Wiring

MHGRV-X Field Technical Guide

5

WIRING

MHGRV-X Stand-Alone Wiring

Stand-Alone Wiring

In Stand-Alone mode, the MHGRV-X connects to the E-BUS port of the Reheat Expansion Module with an EBC E-BUS cable.

See the SAT Wiring Conditions Table and SAT OPTIONS jumper settings in Tables 7 & 8, page 18.

See Figure 3 below.

		MHGRV-X CONTROLLER
		(OE377-26-00059)
0-10VDC			Fan
	-
External Reset			C1
Signal	+		Compressor
			C2
H1 (Dehumidification)			HGR Solenoid Valve
Heating Override
			2 Position HGR Valve (Optional)
Cooling Override			COMM
Mount In Supply
Air Duct
			Condenser Valve #1
Supply			BLK
Air Temperature
Sensor			WHT
			RED
			GRN
			BLK
			WHT
			GRN
			RED
See Table 8 On Page 18			HGR Valve #1
For SAT OPTIONS Jumper Settings.
Only One Supply Air Temperature		GND	24VAC
Sensor Can Be Used Per Application.

	EBC E-BUS
	Cable Connects	40 VA
	To Reheat
		Transformer
	Expansion
		Minimum
	Module
		Line

Figure 3: MHGRV-X Controller Stand-Alone Wiring

6	MHGRV-X Field Technical Guide

INPUTS & OUTPUTS

Inputs and Outputs

I/O Map

The following inputs and outputs are available on the MHGRV-X Controller. See Table 1 below to reference the Input/Output Map.

Analog Inputs

1 Supply Temperature

2 Reset Signal

3 AUX Input - Future Application

Binary Inputs

1 Reheat Enable

2 Heating Override

3 Cooling Override

Relays

1	Fan
2	Compressor
3	Reheat Valve
4	Auxiliary

Table 1: MHGRV-X Controller Inputs & Outputs

NOTE: All analog and 24 VAC contact closure inputs are used only in Stand Alone operation.

Analog Inputs

SAT: Supply Air Temperature Sensor

Used in stand-alone operation and when MODGAS is connected to a CAV/VAV or MUA Controller. 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.

RST IN: Reset Signal

Used only in stand-alone operation. 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.

Binary Inputs

REHEAT EN: Reheat Enable Contact

Used only in stand-alone operation. When a call for dehumidification is initiated by another controller, this interlocked 24 VAC wet contact closure is used to enable the MHGRV-X controller.

HEAT OVR: Heating Override

Used only in stand-alone operation. When a call for heating is initiated by the HVAC unit, this interlocked 24 VAC wet contact closure is used to override the MHGRV-X controller dehumidification mode.

COOL OVR: Cooling Override

Used only in stand-alone operation. When a call for cooling is initiated by the HVAC unit, this interlocked 24 VAC wet contact closure is used to override the MHGRV-X controller dehumidification mode.

Relay Outputs

FAN: Fan Enable

When a call for Dehumidification, Cooling Override, or Heating Override is received, this relay output will be closed to energize the HVAC unit Supply Fan.

CMP: Compressor Enable

When a call for Dehumidification or Cooling Override is received, this relay output will be closed to energize the Compressor(s).

VALVE: Reheat Solenoid Valve

When a call for Dehumidification 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 Dehumidification is received if the modulating HGR valve is at 100% and the Supply Air Temperature is at least 5 degrees below setpoint, this relay output will energize to enable the 2 Position HGR Valve. The relay will de-energize when the modulating HGR valve closes to 0% and the Supply Air Temperature is at least 5 degrees above setpoint. The modulating valve is then enabled to modulate to maintain the Supply Air Setpoint.

COM: Relay Common

Requires 24 VAC from transformer.

MHGRV-X Field Technical Guide

7

OPERATION MODES

Operation Modes

Initialization

The MHGRV-X Controller uses on-board LEDs to indicate various diagnostic conditions during power-up and operation. It also uses the LCD Display to show initialization. Please review this information for a complete description of the controller initialization sequence.

Modulating Hot Gas Valves

The MHGRV-X Controller utilizes two modulating valves to control the flow of Hot Gas through the Hot Gas Reheat Coil. One of these valves is the Condenser Hot Gas Valve and the other is the Reheat Hot Gas Valve. The valves are wired to the MHGRV-X Controller Modulating Hot Gas Valve Output terminals on the controller. These valves work in concert with each other to create a “three-way valve” configuration.As one closes, the other opens, etc.All modes of operation that follow referring to the Hot Gas Reheat Valve are actually a combination of these two valves working together to achieve the specified sequence of operation.

Modes of Operation

The MHGRV-X Controller can be used in two different modes of operation. These modes behave in a similar manner; the main difference is the way they receive information to control the dehumidification process. The following is a description of these modes:

Stand-Alone Operation

As the name implies, in this mode the controller behaves as an independent unit. The controller begins the dehumidification process when the Dehumidification Input “H1” receives a 24 VAC signal from an outside source. When the signal is received, the controller will activate the “FAN” output to energize the HVAC unit fan. At the same time, the controller will initiate Cooling Mode by energizing the “CMP” output starting the HVAC unit compressor. In addition, the controller will open the Hot Gas Reheat Coil by activating the “VALVE” output. At this time, the MHGRV-X Controller will start to modulate the Modulating Hot Gas Reheat valve. The controller will modulate the MHGR valve to maintain the Supply Air Temperature Setpoint by activating the stepper motor outputs on the MHGR valve. The Supply Air Setpoint is configured with the Setpoint Screen in the LCD Display. If Supply Air Temperature Reset is used, it will initiate when a 0-10 VDC signal is supplied to the “RESET IN” input. As the voltage increases from 0 to 10 Volts at the “RESET IN” input, the Supply Air Temperature will be reset towards the Supply Air Reset Temperature Setpoint. This setpoint is configured with the Setpoint Screen in the LCD Display. When a 10 Volt input signal is received at the “RESET IN” input, it will be controlling at the Supply Air Temperature Reset Setpoint. The controller will conclude the Dehumidification process when input “H1” is deactivated, the input “Cool Override” is activated, or the input “Heat Override” is activated.

Operation in Communicating Mode

In this mode, the MHGRV-X Controller behaves as an expansion board for an AAON Unit controller. The controller begins the dehumidification process when theAAON Unit controller makes a request to the MHGRV-X Controller for dehumidification. At that time, the

controller will activate the “FAN” output to energize the HVAC unit fan. At the same time, the controller will initiate Cooling Mode by energizing the “CMP” output starting the HVAC unit compressor. In addition, the controller will open the Hot Gas Reheat Coil by activating the “VALVE” output which opens the Reheat Solenoid Valve. At this time, the MHGRV-X Controller will start to modulate the Modulating Hot Gas Reheat valve. The controller will modulate the MHGR valve to maintain the Supply Air Temperature Setpoint by activating the stepper motor outputs on the MHGR valve. The Supply Air Setpoint is set by programming the HVAC unit controller. If Supply Air Temperature Reset is used, it will initiate when the HVAC sends a request to reset the Supply Air Temperature. The Supply Air Temperature will be reset towards the Supply Air Reset Temperature Setpoint stored in the HVAC controller. It will send a request to move towards the Supply Air Temperature Reset Setpoint based on its setpoints and configuration. The controller will conclude the Dehumidification process when the HVAC control sends a request to terminate Dehumidification or a Cooling or Heating Override request is made by the HVAC unit controller. Any setpoints or signals at the inputs to the MHGRV-X Controller will be ignored.

Additional Features

Reheat Coil Flush

To assure positive oil return to the compressor, the Hot Gas Reheat Coil will be flushed of liquid refrigerant by moving the Modulating Gas Reheat Valve to its maximum position for a short interval.

Cooling Flush: If the unit is in cooling mode, a flush will occur when the unit’s flush cooling interval timer has elapsed. The time is accumulated whenever it is in cooling mode and resets after each flush cycle. The flush cooling interval timer is a setpoint that is configurable using the keypad and display (0 to 120 minutes in 10 minute increments).

Reheat Mode Flush: If the unit is in dehumidification mode and the valve is below 70% for the flush reheat interval timer value, a flush will occur. If the valve goes above 70%, the timer is reset. The flush reheat interval timer is a setpoint that is configurable using the keypad and display (0 to 120 minutes in 10 minute increments).

Optional Second Stage Reheat

On larger systems, where more hot gas reheat capacity may be required, a 2 Position Hot Gas Reheat valve can be connected to the MHGRV-X Controller to be used in conjunction with the Modulating Hot Gas Reheat valve. Any time the reheat demand moves above the Modulating Hot Gas Reheat valve capacity, this 2 position valve would be energized to supply additional hot gas to the Hot Gas Reheat coil. As the reheat demand is satisfied, the MHGRV-X Controller will de-energize the 2 position valve and control reheat with the Modulating Hot Gas Reheat valve.

Reheat Solenoid Valve Control

The Hot Gas Reheat Solenoid valve for the Reheat Coil is activated when there is a call for Dehumidification. In this mode, the Hot Gas Reheat Solenoid will be deactivated 2 minutes after the reheat demand ceases. The Hot Gas Reheat Solenoid valve will be reactivated when a request for reheat is received by the MHGRV-X Controller.

8	MHGRV-X Field Technical Guide