Makeup air calculation confusion

[newB_newyorker]

I want to start brewing in my basement. My pot will sit directly below a window and my plan is to make a diy hood like others have done here on the forum and exhaust directly out the window. I have a 120v Boilcoil that I use for 2-3 gallon batches and I am eyeing up a 500 CFM fan for the exahust that I will only be using during the boil.

I came across this webpage in an older post when researching makeup air: http://structuretech1.com/how-to-determine-if-makeup-air-is-required/

I am confused about the following: Which column on this form would I use to ballpark the makeup air requirement? I have a direct vent furnace and an atmospherically vented water heater? Do I use two separate columns (A and C) and then sum the house "infiltration" estimate? I do have CO detectors on every floor of my house but I don't want to leave anything to chance. Any guidance here would be welcomed.

 

[Bobby_M]

Since you don't have to worry about venting combustion gases, you probably don't need any makeup air. The boil is creating volume so you can forgo the wide capture hood and try to put a focused intake very close to the top of the kettle

 

[newB_newyorker]

Since you don't have to worry about venting combustion gases, you probably don't need any makeup air. The boil is creating volume so you can forgo the wide capture hood and try to put a focused intake very close to the top of the kettle

I'm not worried about combustion gasses from my equipment. I just want to make sure I am not drawing CO from the water heater exhaust back into the house. As far as the "hood" goes, I was just thinking to mount a 8" inline fan to an elbow and a 8" to 12" reducer. The reducer is 12" on one end which is the exact diameter of my pot.