We've built a flat plate solar collector and it seems to work pretty good, But I'm not an engineer and need some info. we set it up outside just to test it and let it draw in ambient temp air at about 30 degree's Farenheit. on a sunny day we got output temp of about 100 degrees. so a gain of about 70 degrees. on an overcast day we only gain about 20 degrees. What I want to know is if I draw in 65 degree air from the house instead of 30 degree outside air, will I still get the same temperature gain, or will the output temp stay the same? so on overcast day, the internal temp would be cooler than the house air. once the house air warmed the absorber plate to 65 degrees, would we then get output temp of 85 degrees? or would it just cool the inside air?