Index: dialin/common/msg_ids.py
===================================================================
diff -u -r0decd02e6202cacf8daf0cfc8a7fa6ac67da5ad7 -r68197254bdb86290c04a7cf222ae123970fd7cdb
--- dialin/common/msg_ids.py	(.../msg_ids.py)	(revision 0decd02e6202cacf8daf0cfc8a7fa6ac67da5ad7)
+++ dialin/common/msg_ids.py	(.../msg_ids.py)	(revision 68197254bdb86290c04a7cf222ae123970fd7cdb)
@@ -384,6 +384,7 @@
     MSG_ID_HD_RAM_STATUS_OVERRIDE = 0x8099
     MSG_ID_HD_VALVES_STATES_PUBLISH_INTERVAL_OVERRIDE = 0x809A
     MSG_ID_HD_CAN_RECEIVE_ACK_MESSAGE_OVERRIDE = 0x809B
+    MSG_ID_HD_RECIRULATION_PCT_OVERRIDE = 0x809C
 
     MSG_ID_DG_TESTER_LOGIN_REQUEST = 0xA000
     MSG_ID_DG_ALARM_STATE_OVERRIDE = 0xA001
Index: dialin/hd/reservoirs.py
===================================================================
diff -u -r9bc00e997e91dab8b404aa877b02ae3d4100d417 -r68197254bdb86290c04a7cf222ae123970fd7cdb
--- dialin/hd/reservoirs.py	(.../reservoirs.py)	(revision 9bc00e997e91dab8b404aa877b02ae3d4100d417)
+++ dialin/hd/reservoirs.py	(.../reservoirs.py)	(revision 68197254bdb86290c04a7cf222ae123970fd7cdb)
@@ -22,7 +22,7 @@
 from ..common.msg_defs import MsgIds, MsgFieldPositions
 from ..protocols.CAN import DenaliMessage, DenaliChannels
 from ..utils.base import AbstractSubSystem, publish, DialinEnum
-from ..utils.conversions import integer_to_bytearray
+from ..utils.conversions import integer_to_bytearray, float_to_bytearray
 
 
 @unique
@@ -90,10 +90,37 @@
             message['message'][MsgFieldPositions.START_POS_FIELD_6:MsgFieldPositions.END_POS_FIELD_6]))[0]
         self.time_wait_to_fill = struct.unpack('i', bytearray(
             message['message'][MsgFieldPositions.START_POS_FIELD_7:MsgFieldPositions.END_POS_FIELD_7]))[0]
-
-
         self.temp_remove_fill_flow = struct.unpack('f', bytearray(
             message['message'][MsgFieldPositions.START_POS_FIELD_8:MsgFieldPositions.END_POS_FIELD_8]))[0]
 
         self.hd_reservoirs_timestamp = timestamp
 
+    def cmd_recirulation_pct_override(self, recirulation_pct: float) -> int:
+        """
+            Constructs and sends a recirulation percentage override message to the HD.
+            Constraints:
+                Must be logged into HD.
+
+            @return: 1 if successful, zero otherwise
+        """
+        pct = float_to_bytearray(recirulation_pct)
+        payload = pct
+
+        message = DenaliMessage.build_message(channel_id=DenaliChannels.dialin_to_hd_ch_id,
+                                              message_id=MsgIds.MSG_ID_HD_RECIRULATION_PCT_OVERRIDE.value,
+                                              payload=payload)
+
+        self.logger.debug("Setting recirulation percentage.")
+
+        # Send message
+        received_message = self.can_interface.send(message)
+
+        # If there is content...
+        if received_message is not None:
+            self.logger.debug("Recirulation percentage set to to " +
+                              str(received_message['message'][DenaliMessage.PAYLOAD_START_INDEX]))
+            # response payload is OK or not OK
+            return received_message['message'][DenaliMessage.PAYLOAD_START_INDEX]
+        else:
+            self.logger.debug("Timeout!!!!")
+            return False