Co2 level – Shellab SCO2W-2 User Manual
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1/ verify that controller is asking for heat by looking for controller light
– if
pilot light is not on continuously during initial start up there is a problem with 
the controller 
2/ check amperage 
– amperage should be virtually at maximum rated (data
plate) amperage 
3/ do all controller functions work? 
4/ is the OTP set high enough? 
– for diagnostics, should be fully clockwise
with the pilot light never on 
5/ has the fuse/circuit breaker blown? 
Indicated chamber temperature 
unstable 
1/ ±0.1 may be normal 
2/ is fan working? 
– remove top panel and verify movement of cooling fan in
center of shadow box 
3/ is ambient room temperature radically changing 
– either door opening or
room airflow from heaters or air conditioning?
– stabilize ambient conditions
4/ sensor miss-located, damaged, or wires may be damaged - check 
mounts for control and OTP sensors, then trace wires between sensors and 
controls 
5/ calibration sensitivity 
– call Customer Service
6/ OTP set too low
– be sure that OTP set point is more than 5 degrees over
desired Main set point; check if OTP pilot is on continuously; turn controller 
knob completely clockwise to see if problem solved then follow instructions in 
section 5.8.E for correct setting. 
7/ electrical noise 
– remove nearby sources of RFI including motors, arcing
relays or radio transmitters 
8/ bad connection on temperature sensor or faulty sensor 
– check
connectors for continuity and mechanical soundness while watching display 
for erratic behavior; check sensor and wiring for mechanical damage 
9/ bad connections or faulty capacitor 
– check connectors for mechanical
soundness and look for corrosion around terminals or signs of arcing or other 
visible deterioration 
Will not maintain set point
1/ assure that set point is at least 5 degrees over ambient room temperature 
2/ see if ambient is fluctuating 
Display and reference thermometer 
don’t match 
1/ calibration error
– see section 5.4
2/ temperature sensor failure
– evaluate if pilot light is operating correctly
3/ controller failure
– evaluate if pilot light is operating correctly
4/ allow at least two hours to stabilize 
5/ verify that reference thermometer is certified 
Can't adjust set points or calibration
1/ turn entire unit off and on to reset 
2/ if repeatedly happens, call Customer Service 
Calibrated at one temperature, but not 
at another 
This can be a normal condition when operating temperature varies widely. 
For maximum accuracy, calibration should be done at or as close to the set 
point temperature. 
CO2 LEVEL
Overshoots set point but stabilizes - 
display and Fyrite match 
