produces the best overall operation. Be sure to check all applicable federal, state, and local
guidelines as these may dictate the required concentration.
Delay Period Set Incorrectly
Using a long delay period can produce a situation in which a rapidly increasing gas level may
rise to dangerous concentrations before the ventilation system activates. Also, smoke from the
engine exhaust could build up to a point where people in the area begin to experience irritation
in their eyes and nose. Choose a delay setting that activates the fans and begins to clear the
area before the gas rises to a dangerous concentration, or eye and nose irritation happens.
Setting the delay period too short will cause frequent operation of the ventilation system. The
detector may activate the fans after sensing a transient gas concentration. Once the fans
activate, this transient level will drop quickly causing the detector to turn off the fans. In this
case, the ventilation system operates frequently and wastes energy. Increase the delay setting
until a compromise is reached that keeps the target gas level below that specified in the
regulatory standards without operating the ventilation system too often.
Setting the Proportional Output Incorrectly
If a controller connected to the proportional output is expecting a certain output signal, the
jumpers on JP2 and JP3 of the sensor board must be configured to output that type of signal.
A common mistake is leaving JP2 set to mA while moving JP3 to the desired voltage output.
This causes the unit to read between 12 and 15 VDC with the output not changing proportional
to the sensor’s gas readings.
Detector Mounted in an Unsatisfactory Location
For reliable operation, the detector(s) must be mounted in the proper locations. Please read
“Mounting the Detector” on page 14 for guidelines on choosing locations.
Common mistakes include mounting a detector too close to a garage door. When the door is
open, rain may blow through the doorway and onto the detector housing. Another common
mistake is to mount the detector in a location where it comes in direct contact with engine
exhaust. The large amount of contaminates in engine exhaust can shorten the useful life of
the sensor.
One more common mistake is to choose a mounting location that places the detector too near
the outlet of air conditioners or heaters. Quick, drastic changes in ambient temperature can
cause erratic shifts in the detector readings.
By following the mounting guidelines, many of the problems caused by improper mounting
locations can be eliminated.
IOM01
Rev 1.0 – December 22, 2020 37
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