User Guide
Zoning System Design Manual
7 70-2321—06
M36666
HORIZONTAL
UP-FLOW
DISCHARGE AIR
TEMPERATURE SENSOR (DATS)
ROOF TOP EQUIPMENT
THE DATS MUST BE LOCATED SO THAT IT CAN
PROPERLY SENSE THE LEAVING AIR
TEMPERATURE.
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.
Fig. 5. DATS mounting locations.
PRESSURE RELIEF DAMPERS AND DATS
Setting the Regulator
The CPRD is factory set to open at approximately .5"WC." This setting is
satisfactory for most installations. Some
systems have higher static pressure. Test this by:
1 Make all zones call fan, heat, or cool; whichever has the highest CFM.
2 Verify that the damper position indicator points to closed.
3 If it does not point to closed:
• Flip the adjustment crank out (see Fig. 4)
• Push down on the adjustment crank with gentle pressure. Caution:
Do not rotate the adjustment crank without first pushing it down
• Turn the adjustment crank clockwise until the indicator points to
closed
• When done, flip the adjustment crank back into the locked position
4 Make only the smallest zone call for fan, heat, or cool.
5 Verify that the airflow into that zone is not objectionable. If it is, then set
the regulator to a lower pressure.
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. It is recommended to set the
high limit approximately 15°F below the furnace high limit. Some modern furnaces have low high limit settings, so
make sure the correct zone panel is selected for the equipment.
The HZ221 zone panel is for heat pumps only and has a fixed high limit (120°F for heat pump and 160°F for aux
heat) and low limit (45°F).
The HZ311 has a fixed high limit (160°F) and low limit (45°F).
The HZ322 and HZ432 zone panels have adjustable high limit (110°F180°F) and low limit (30°F60°F).
Note: It is often advisable to install the DATS in the bypass duct rather than supply duct for heat pumps with elec-
tric auxiliary heat.
M34210
Fig. 4. Adjustment crank.