Contherm MITRE 4150 - Page 60

MANUALP/4000_SERVICE_0712 July2012
60
b. If the cabinet display is reading too high CO
2
concentration
compared with the external CO
2
meter, then the IR constant should
be adjusted slightly DOWN. Conversely, if the cabinet display is
reading too low CO
2
concentration compared with the external CO
2
meter, then the IR constant should be adjusted slightly UP.
c. To adjust the IR constant or Span, connect the shorting jumper pins
on JP5 and JP4 respectively.
d. Connect a voltmeter to the IR
CO
2
sensor board output
terminals. This is the terminal
with wire going to the ZP22
interface controller board.
Measure the initial IR constant
value.
e. Depending on the difference
of CO
2
concentration
between the external meter
and the cabinet display,
press either the ‘UP or
‘DOWN’ button VERY briefly
and then record the new IR
constant value. Ensure that
JP4 and JP5 still have the
shorting jumper pins inserted.