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Vacuum Calibration
Display Example #17
This Vacuum Test utility’s primary function is to calibrate the vacuum transducer. The transducer’s
worst case error is rated at + or – 5%, thus the ability to increase or decrease the Actual Vacuum value
by +/- 5%. This calibration is performed at the factory using precision vacuum gauges and should
never need adjusting.
NOTE!
The actual
Vacuum Adjust
value should be written down inside your manual should you need
to change this value and restore it at a later time.
The Vacuum Calibration utility is also a powerful tool for helping to diagnose vacuum issues with
either the vacuum pump or the furnace. By running a very simple test it is easy to determine if you
have a vacuum leak in the furnace or a bad vacuum pump. Enter a lower than normal vacuum level
into the Test Vacuum box, for example, 650 mmHG. Touch the Start button. The platform will rise, if
not already up, and once at the top the vacuum pump will start. Note that while the platform is rising
the Actual Vacuum will show a value of 10 mmHG or more. This is normal and does not indicate a
problem. As the vacuum rises, if the pump is strong enough it will exceed 650 mmHG by 3 mmHG
and will then shut off. There will be some loss of vacuum level due to the valves closing and pressure
stabilizing throughout. If it takes a minute or more before the pump restarts then the furnace is holding
vacuum well enough to achieve higher vacuum levels. The problem is in the vacuum pump and needs
replacing. This can be confirmed by entering a higher value in the Test Vacuum box. At some point the
pump will be unable to achieve the required vacuum level.
Start
Stop
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0
Vacuum Test
Test Vacuum (mmHg)
Actual Vacuum
0 mmHg
Vacuum Adjust ± 5%
+/-
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Summary of Contents for SUMMIT
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