Shellab SRI20-2 - Manual (Page 11)

11
Unit will not heat up at all
1/ verify that controller is asking for heat by looking for controller light – if
pilot light is not on continuously, 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 Thermostat 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 Thermostat sensors, then trace wires or tubing
between sensors and controls.
5/ calibration sensitivity
– call Customer Service
6/ Overtemperature set too low – be sure that the thermostat is more
than 5 degrees over desired set point; check if OVERTEMP pilot is on
continuously; turn controller knob completely clockwise to see if problem
solved then follow instructions in owner’s manual for correct setting – see
section 5.7
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 relay
– 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 -
2/
SEE IF AMBIENT IS FLUCTUATING
Display and reference thermometer don’t
match
1/ calibration error – see section 5.6
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/ see if 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 as close to the set
point temperature.
REFRIGERATION
Temperature can't get up to set point
1/ assure that power is going to heating coils.
2/ if the displacement is erratic, see if air is being circulated.
3/ confirm that controller is calling for heat (check front panel light).
4/ if light not coming on, check control set point and Overtemperature set
point .
5/ confirm that fan is operating and airflow is not blocked.
6/ reset by turning unit off and on.