Dwyer 670 - Manual (Page 11)

10
1.3 Start up
When unit is powered up the following sequence of events occur:
1. The 12V DC power is applied to the airflow sensor and the alarm then performs a self test
on the functions, LEDs and audible alarm (approx 2 sec) and then initiates a delay timer to
allow the airflow sensor to stabilize.
2. During the whole of the delay period all alarms and relay outputs are inhibited and the Red &
Green LEDs will be permanently ON.
3. At the end of the delay period the unit performs one of two options:
a. If the alarm calibration has been previously completed - the unit goes to normal
operating mode (Run).
b. If the unit has not been calibrated - the Red & Green LEDs will flash on/off and the
audible alarm will be muted. It is then possible to press the Enter button for 5 secs
and go into the calibration mode – (See ‘Quick Start Installation’ below for details of
the Calibration procedures).
AV-670:B-32 10/1/09 2:20 PM Page 11