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MHGRV-X Field Technical Guide
APPENDIX B: MHGRV II
MHGRV-X Replacement of MHGRV II
Replacing the MHGRV II with the
MHGRV-X
The drop-in replacement involves a few easy steps.
Refer to Figure 7, this page.
Stand-Alone Mode Operation
Step 1: Disconnect power from the MHGRV II.
Step 2: Disconnect the Supply Air Temperature Sensor from
the MHGRV II and wire it to the MHGRV-X. If the
Supply Air Temperature Sensor is being shared with a
Stand-Alone MODGAS Controller, maintain the same
wiring with the MODGAS Controller.
Step 3: Separate the HGR Valve wires and the Condenser Valve
wires onto the appropriate Reheat Drive and Condenser
Drive terminal blocks per Figure 3, page 8. Wire all
other inputs and outputs per Figure 3.
Step 4: Set the SAT Options Jumper per Table 9, page 21.
Step 5: Connect power to the MHGRV-X.
Communications Mode Operation
Step 1: Disconnect power from the MHGRV-II.
Step 2: The Supply Air Temperature Sensor needs to remain
installed on whatever controller it is currently on. If it
is currently installed on the MHGRV II then reinstall
it on the MHGRV-X. If it is currently installed on the
main unit controller or on a connected MODGAS, it
needs to remain there.
Step 3: Set the SAT Options Jumper per Table 10, page 21.
Step 4: Connect power to the MHGRV-X.
Line Voltage
GND
18-30 VAC
Supply
Air Temperature
Sensor
Mount In Supply
Air Duct
Only one Supply Air Temperature Sensor
can be used per application.
IC Cable connects to
AAON unit controller’s port
2
1. 24 VAC must be connected so
that all ground wires remain common.
2. All wiring to be in accordance
with local and national electrical
codes and specifications.
Connect to a MHGRV-X in Stand-Alone Mode
or when using a VAV/CAV or MUA controller.
If also using a MODGAS controller
in Stand-Alone Mode, the SAT Sensor
connects to the MODGAS controller.
Figure 7: MHGRV-X Replacement Wiring
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