These three numbers are simply different ways of saying exactly the same thing.
The only thing we are aware of which will cause a Bacharach instrument to falsely read as carbon monoxide is hydrogen, from charging a battery, for example.
There are two possible causes. Obviously if the CO sensor is bad, an error message will be displayed. If the instrument goes through an 'automatic' calibration during the 60 second warm up period (see #13) and detects more than approximately 80 ppm's of CO in the ambient air, it will also read CO sensor error.
Should this error message occur, immediately shut the instrument off, go outside and turn it on again. If it successfully goes through the 60 second calibration cycle, return to the work area while watching the CO reading to determine if the area is contaminated.
Above 15%, it is virtually impossible to have combustion occurring in a typical heating system
Yes, all manufacturers of carbon monoxide and combustion test instruments recommend calibration of the CO sensor every 6 months. If applicable, the temperature, pressure and flow rate are also checked/calibrated when an instrument is sent in for calibration.
It is also very important to keep the probe/hose assembly and sensors free of any condensate. This will greatly extend the life of the sensors and electronics. After each use, disconnect the hose assembly from the instrument and allow it to purge for an additional 10 minutes or so to remove any moisture. Replace the yarn in the moisture trap regularly and empty the trap if any moisture has accumulated. You may also want to leave the moisture trap open when packing it in the case to dry it out.
Bacharach's O2 and CO sensors are under warrantee for two years. If properly maintained (see #5), the oxygen sensor will generally last 2-3 years and the CO sensor life may be as long as 5-6 years.
All manufacturers of combustion and CO test instruments recommend calibration every 6 months.
Most of Bacharach's instruments can be calibrate by the end user. The only one which is more difficult is the PCA. It has a hydrogen compensated CO sensor which requires two tanks of calibration gas to perform the procedure and the calibration process itself is more difficult.
The Fyrite Pro, Monoxor II, and Model 300 can be calibrated by the user, however, many customers would rather send it in just in case certification issues arise. Also, keep in mind that when an instrument is sent to a service center for calibration, temperature and pressure sensors are also calibrated as well.
Typically, the probe should be placed so that it samples combustion air temperature. Some instruments determine combustion air temperature during the 60 second warm up period in order to calculate the SSE reading.
DO NOT place the probe in the stack or test sample location until it has finished the 60 second warm up period. This will not damage the instrument, but will (in all likelihood) provide a false Oxygen reading once the heating equipment is being tested.
Typical cold winter weather will not damage the instrument. However, when a cold instrument is brought into a warm, moist environment, condensate may accumulate on the electronic circuit board and cause damage. It's always a good idea to bring the instrument inside during cold (below 30 degrees F) periods.
Should an instrument be accidentally exposed to cold temperatures, bring it inside and allow it to warm up slowly