Our attic is unbelievably hot. The man that came to check our coils said we needed to check the soffit vents. We did & enlarged the openings, plus added some new vents. It is still too hot up there. Our roof ridge vent is relatively short, because of the shape of the roof... so he suggested we install a 'power vent' to control the air flow & temperature. Does anyone know if these really work well?