90
2004 – 2014 Reliable Controls
®
Corporation. All rights reserved.
6
Wait until the FL-CAL point value resets to 0. This may take up to one minute.
During this time the MACH-Air
™
is calibrating the airflow sensor.
F
IGURE
80: SS-L FL-CAL
POINT
7
When the FL-CAL point value reads 0, the K-factor constant multiplier for the VAV
box has been set and the airflow transducer has been calibrated.
8
Use the
button to step to the FLOW point on the SS-L and wait until the
displayed calculated flow stabilizes near the FL-OVR setting.
F
IGURE
81: SS-L FLOW
POINT
9
For best practice, verify the total actual flow by measuring the airflow through
each connected distribution outlet using an accurate balancing hood again. If
the difference between the actual total measured airflow and calculated total
airflow displayed by the SS-L is outside of the specified or acceptable limits (5%
- 10% typical), repeat steps 5–8.
10
If it is necessary to balance or test the VAV box at the configured minimum
airflow setpoint, repeat steps 2–4 using the minimum airflow setpoint for the FL-
OVR value.
The actual total measured airflow with the box operating at the minimum flow
setpoint may be measured. However, do not re-calibrate the K-factor based
upon the minimum airflow setting. The flow transducer is more accurate at
higher air velocity.
11
Set the FL-OVR point value back to 0 to allow the MACH-Air
™
to revert to normal,
programmed operation.
12
The calibration procedure is now complete.
A typical value for the K-factor of a MACH-Air
™
/MACH-ProAir
™
is from 0.5 to 1.5. If the
calculated value is outside of this range, there is likely a problem. Most airflow pickups
amplify the differential pressure to allow for a better resolution of the signal by the
differential pressure transducer. For this reason, the constant multiplier K is usually < 1.0 in
order to remove the amplification.
