[Xringer]

Right now, the programed setpoint temp(of attic air) for turning on the fans is the basement temp+4 deg F.
In the afternoon, the attic has to be 6 deg F warmer than the basement.

With the current setup, there is never any cold air pumped into the basement.
It's always at least 4 degs warmer than the basement air. It's just not making a dent..

Right now, it's sunny and Temperature Sensors show 58.2 F in the basement and 60.2 F in the attic.
The fans aren't on yet.

What I find interesting about the plots, is the absents of effect on the attic temperatures.
I expected to see a drop in attic air temperature, shortly after the fans came on.
This leads me to think there is a lot more warm air available in the attic,
than my 200 CFM fans are pulling down..

I had this idea, the fans would be turning off and on as the attic cools, and re-warms.
But that never happens. Once the sun has been gone a while, it shuts down.

There is residual heat in the attic for hours, depending on the outdoor temps,
it's not long before the attic temp become very close to outdoor temp.
(You can see the plot lines merge on some of the charts).
I don't see much to indicate more attic insulation is needed.
Of course it would help, but the amount of gain for labor required, is questionable.

I understand what snow cover does, I've had a sensor in the attic for years.
During the winter, I still might want to bring in a shot of fresh dry air,
even if it's cold up there.
Since I have a feeling the basement will recover fairly fast..
I may interface one of my Radon detectors into the CAI controller..
That cold air shot will cost me BTUs, but it will make the basement safer.