Environmental Technologies Air Terminal Unit SDR-22

Disconnect actuator from the controller.

Apply 24 VAC to the COM and CW terminals on the actuator.

Did the actuator rotate in a clockwise direction?

Apply 24 VAC to the COM and CCW terminals on the actuator.

Did the actuator rotate in a counter clockwise direction?

Did the actuator move in both directions?

Did the actuator fail to rotate?

Refer to the 'Electric Heat, All Products' IOM for complete electric heater installation, operation and maintenance information.

Check the primary auto-reset limit switch for proper operation.

Inspect the secondary one-time trip limit switch for tripping.

Replace the secondary limit switch if it has tripped, ensuring the new switch has the same trip temperature as the original.

Check if an optional manual reset secondary is available and reset if necessary by depressing the reset switch.

Verify airflow is at least 70 CFM per kW.

Ensure a minimum of 0.1" w.g. external pressure is maintained.

Electric Heater Rack Replacement

Turn off power supply before servicing

Locate T-Plate inside on heater control enclosure

Mark where the wires are connected on the T-Plate before removing them

Remove the wires and screws holding the heater T-plate in the control enclosure and remove element rack

Insert new element rack into control enclosure and replace screws to secure the element rack to control enclosure

Close control enclosure cover before turning on the power

Inspect for microbial growth on coil surface

Disconnect all electrical power to the equipment

Gain access to coil through ductwork or access panel

Use soft brush and vacuum to remove loose debris from sides of coil

Mechanical Angle of Rotation Stops

Loosen the two end stop screws using a No. 2 Phillips head screwdriver, being careful not to unscrew the captive nut under the slot.

Move the stops to the desired position (in 2.5° steps).