Static Pressure Decrease????

[swampboy]

I just got a new carrier infinity installed a few weeks ago and the static pressure was 0.36 @ 1008cfm. It is now 0.28 @ 1008cfm. How is that possible? Could I have developed a leak in my duct? Can the S.P. change with temperature??? The original readings came during a heat wave and the latest was in the evening. What makes it change?

[mark beiser]

Yes, the static pressure can go down.

Possible scenario:
If the higher reading was when it was first installed, and pulling the temperature down in the house, it may have been a lot more humid in the house, so a lot more water on the coil restricting airflow, which will cause the blower to speed up to maintain airflow.
Once the house is cooled down, and dehumidified, there is less water on the coil, so the blower can move the same amount of air at a slower speed.

[beenthere]

What Mark said.