Is anyone able to explain the differences in these two products and how to determine which is correct for controlling drafts into a house when the furnace as well as other combustion appliances are operating? Is one more efficient than the other? The application in question is a forced air natural gas mid eff. furnace, I am unsure of the benefits of dumping the air into the cold air return, especially in Michigan.
Also, will either one of them provide replacment air into the house when a 500cfm range hood fan is operating?