I don't know Michigan regulations, but in PA, Labor and Industry allows a louvered vent for combustion air inlet. Nothing fancy. If a negative pressure develops in the room, the vent swings open on its own.

I wondered about this, what would you call that style of damper or vent?

Thank you

Look under Grainger.com under vents. Either wall or supply vents. My computer won't load the pages.

Ok I see the type you are talking about, I guess my only concern is the wind being able to blow it open.

Thanks for your input

Anyone else want to chime in?

Our vent was on the north side of the building and I never noticed that wind was an issue.

There are motorized dampers that can be interlocked with the combustion appliances. They only allow operation of the combustion device if the door is in the open position.

I have only looked at the ones scaled for residential applications, but I can't imagine that they would not be available larger. YOu can install more than one to scale the amount of air need, but it might be a lot more expensive. Google will find them.

I used to maintain a pair of furnaces that used a mechanized damper. The original furnaces had been installed in the mechanical room with no outside air and there were constant problems with soot. After the damper was installed problems went away. There is an interlock so the damper opens before either burner can fire. I don't know where the damper came from, too long ago but it's been very reliable and because the room is fairly airtight due to fire code, there's no problem with cold air in the adjoining room.