Has anyone used a roof venting system (intake air) like Smartvent
In our family we have a 1940s house with a relatively low slate roof which we need to replace. We have decided on asphalt shingles. The house has no place for soffit vents and currently has one gable vent. Other than this low attic space (you can't stand up in the middle) getting very very hot in the DC area summer there have been no problems with this roof set up - no leaks or condensation that we can see over the past 70 years and although only used to store boxes it would be nice to be able to access it in the summer.
Although with a new roof there are many seemingly viable options for venting the hot air (ridge vents, solar vent fans etc.) these will only work if the intake air is sufficient and without the possibility of soffit vents this is problematic.
I read a bit about the smartvent system where a vent for intake air is put into the bottom part of the roof decking but I have not read any independent studies or reviews of this system. Are there any other systems and does anyone have any information to share on this issue in general. In our area there are hundreds and thousands of houses like this one and most of them I see with retrofitted asphalt roofing have no vents other than the mostly one gable vent the house came with when it had a slate roof. A big market here I would think. Any help much appreciated.