I have a brand new house with double pane single hung aluminum windows (builder's grade) My problem is that when the heater is on I have so much condensation on the window frames (not the glass) that water puddles on the window sill - so bad that it is starting to rot out my sheet rock on the side of the openings. My builder got with the AC installer and he suggested we add a fresh air vent to the hvac plenum in order to add some humidity. (that didn't make sense to me) That helped but the windows on both ends of the house are still condensating. My builder suggested setting the thermostat to 68 to see if it stopped the condensation. It condensated less but I still have water. Please help!