You will need to turn the fan around so the flow rings and flow sensor are outside. Older fans have a reverse switch, but the switch cannot be used when you are measuring air flow. If the DG-700 is inside the house, you will also need to install a third tube on your DG-700. That tube will go from the reference tap of channel B to the outdoors near the side of the fan, but not in the fans airstream.
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