I do not understand the concept of measuring the Static pressure.
Today, I went to an A/C call, found a totally plugged filter and decided to do a little experiment. To be specific, I decided to take Static pressure reading with and without the "plugged up" filter.
So, I drilled a hole above Evap. coil and one on the Return duct very close to the filter (2-3").
Here are the readings I took:
- above Evap. coil ==> 0.09"w.c.
- just before the filter ===> (-0.25"w.c.) that is without the filter.
- when put the "plugged up" filter in ==> (-0.05"w.c.)
Seems that when the "plugged up" filter is IN, the readings are less. And I was expecting to see higher readings.
That tells me that when the air flow is slowed, the readings are less (smaller).
But when the filter is OUT (of washed) there is more airflow passing through the my "hooks-sensors", thus the higher readings.
I am totally confused.
If I block all my Return openings in the entire house - what kind of readings should I expect before the filter ??? Higher or smaller .... readings ,,,,, ???