M-20 Operation And Maintenance Manual
83550-003-001 Revision C
2008-01-03
12
Item
Name
Item Range
Default
Description/Function
“AutoZero”
“Yes” or “No”
“No”
When “AutoZero” is set to “Yes”, the unit
will gather the lowest ppm reading in an
8-day period and set the unit calibration
so that the lowest reading indicate the
global average of around 360ppm.
When “AutoZero” is set to “No”, the unit
will not adjust its own calibration and work
off the last manual or factory calibration.
NOTE:
“AutoZero” works best in situations where
the building will purge at night (or over a
weekend) to the global average CO
2
concentration.
“Altitude”
0 to 9999 feet (ft)
300 ft
The altitude of the installed unit above sea
level in feet. Can be set in steps of 50 ft.
“PassWord”
0000 to 0255
0017
User password, required for entering the
menu system.
NOTE:
Please make sure you keep a record of the
password if changed.
“Relay”
“Enable” or “Disable”
“Enable”
Select “Enable” to update the relay status
from the measured concentration.
When “Disable” is selected, the relay is
passive and remains non-energized.
“Relay On”
0 – 5000ppm
1000ppm The concentration at which the relay will
be energized.
NOTE:
If “Relay On” is set lower than “Relay Off”,
the relay will energize when the
concentration drops below the
concentration set for “Relay On”. This
causes and inverted relay action.
“RelayOff’
0 – 5000ppm
NOTE:
Do not set the dead
band to be lower
than 50ppm to allow
proper operation of
the relay.
950ppm
The concentration at which the relay will
be de-energized.
NOTE:
The dead band is the difference between
“Relay On” and “Relay Off”. The default
dead band is therefore 50ppm.
“Delay On”
0 – 60 minutes
0 min
“Delay On” is the time delay in minutes
after the concentration passed the “Relay
On” concentration until the relay is
energized.
This delay can be used to eliminate
nuisance fan start-ups. The delay can be
set in increments of 5 minutes.
