This feature was added to Tracer TU starting in Version 12
Use the Calibrate ECM dialog box to drive the fan to maximum speed so you can take physical air flow measurements. Tracer TU uses your measured value to calculate and set the necessary data points that affect maximum fan speed. This dialog is similar for fan-powered VAV boxes that operate with variable speed and those that operate at a constant speed. The dialog shown below is from the variable speed application, but differences in the constant speed application are noted.
Access
Select the Flow Calibration tab and then open the Actions expanding box.
Dialog Box Content
(1) Current Operating Status – This section displays values at the time the dialog box is opened. It then provides continuously updated values for these points reflecting the active status.
(2) Fan Speed Override Status – This value displays the override status of the ECM fan. To maintain consistency with other equipment with ECM fans, the values displayed here will be “Auto” if no override is present and “High Speed”, “Low Speed”, “Medium Speed”, or “Off” if associated overrides are present.
(3) Current Fan Speed Output – This value displays the active speed status of the ECM fan in percent.
(4) Fan Speed Setpoints – This section displays values and actions necessary for setting fan speed setpoints to match design values. Variable fan speed applications include input fields for Supply Fan Cooling Max, Supply Fan Heating Max, and Supply Fan Minimum. Constant speed applications only include the Supply Fan Cooling Max input field.
(5) Override Setpoints – Clicking this button after changing the value in any of the setpoint input fields places a temporary (4 hour) override on the associated data points. These values will be set permanently when the Apply or Done button is clicked. This temporary override also allows you to cancel any changes you’ve made so far by clicking the Cancel button.
(6) Set Fan Speed – This section displays values and actions necessary for setting maximum fan speed to provide design maximum air flow.
(7) Override Fan – This button places a temporary (4 hour) override on the ECM fan, driving it to maximum speed. The button is labelled Override Fan Max Cooling for variable fan speed applications and Override Fan On for constant speed applications. The override status should be reflected in the Current Operating Status section. After allowing some time for the fan to reach operating speed, physical air flow measurements can be taken.
(8) Current Fan Air Flow Setpoint – The value reported here should match the value entered in Supply Fan Cooling Max input field after clicking the Override Fan button.
(9) Actual Air Flow – Enter the value you obtained from your measurements in this field.
(10) Calculate – This button calculates the correct data point value to adjust the ECM fan maximum speed based on the entered Actual Air Flow. A temporary (4 hour) override will be placed on this point so further measurements can be taken if desired before setting them permanently by clicking the Apply or Done button. This temporary override also allows you to cancel any changes you’ve made so far by clicking the Cancel button.
(11) Calculation Results – This section displays values affected by any calculation performed. ECM fan-powered VAV boxes use the ECM Fan Correction Factor point for speed calibration. Since a fan cannot deliver greater than 100% of its design, the calibration operation cannot result in a factor greater than 1.0. The value in this section is continuously updated to reflect the active status.
(12) Done – This button sets the default values for all data points necessary for ECM fan speed calibration, releases all overrides made during the calibration process, returns the equipment to normal operation, and closes the dialog box. It is enabled after the Calculate button is clicked.
(13) Cancel – If you have made any changes in the controller without clicking Apply, this button allows you to cancel any changes you’ve made so far and close the dialog. Clicking Cancel in this scenario will bring up a Save? dialog that allows you to save your changes and exit, to exit without saving, or to return to the main dialog.
(14) Apply – This button sets the default values for all data points necessary for ECM fan speed calibration, releases all overrides made during the calibration process, and returns the equipment to normal operation. The dialog box will remain open to allow you to complete further calibration, if desired. It is enabled after the Calculate button is clicked.