i had a feeling someone would point that out!! Yes my physics based degree allows me to understand this concept. I, however, feel that there is something special about this house and the way it draws heat upstairs. It may be lack of insulation or the intake on the second level the pulls heat up. Either way its not normal for a second story thats blacked out to reach 85. right? but my question remains.... at what temp should i start to get concerned?