Alternative Bypass Methods
If there is no space for bypass ductwork, the zone dampers can be set to allow some air to leak. By setting the
larger zone dampers to a minimum position, excess air pressure can be relieved even when only one zone is call-
ing. This method does not typically affect room temperature, but the homeowner should be advised that air will be
coming from these registers even when that zone is not calling.
Discharge Air Temperature Sensor (DATS)
The DATS should be located in the supply trunk between the evaporator coil or heat exchanger and the first zone
damper. If this is not possible, it is permissible to mount the DATS in the bypass duct.
THE DATS MUST BE LOCATED SO THAT
IT CAN PROPERLY SENSE THE LEAVING
NOTE: MOUNTING THE DATS TOO CLOSE
TO THE HEAT EXCHANGER OR EVAPORATOR
COIL WILL CAUSE EXCESSIVE CYCLING OF
THE SYSTEM AND RESULT IN DISCOMFORT
FOR THE BUILDING OCCUPANTS.
TEMPERATURE SENSOR (DATS)
Fig. 4. DATS mounting locations.
ByPass damPers and dats
Zoning System Design Manual
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