Hello everybody. I work in the trades too, I do heating and cooling. However, I am definitely not a DIYer on roofing. I decided to hire a pro for the job to be done right! We are really happy with the company we are going with. I just have one problem. I need to buy a roof-mounted power ventilator. As a heating contractor I have assisted with the installation of these before, but never had to “size” one for appropriate ventilation.
Here’s the issue: My roofing contractor came out and did some calculations and said that my attic needs X-amount of sq. inches of intake ventilation in the soffit vents. We have a shallow-hipped roof and could not get the proper amount of ventilation from ridge vents, so he recommended that I purchase a power-vent. I want a balanced system. So I don’t want to get a vent with too little power to keep things cool and dry up there. But I also don’t want to get one that will be so powerful that it will exhaust more than can be intook from the soffits and start pulling from the structure itself.
First of all, I am wondering if I am just over-analyzing the situation? Should I just get a big 'ol power ventilator? Or do I need to do some calculation to determine the propler type/size of unit?
The problem is I know how many sq. inches of intake I will have, but I don’t know how to transfer that into how many CFM of exhaust I should have?