Here is a picture of the vent cover that Ron has over his furnace opening. I took this picture at IRG. This is to keep mud dauber wasps out. He said that it's a standard RV style cover that attaches with a tiny spring. No drilling necessary. If Ron is reading this, perhaps he will tell us where to get one.
		
		
	
	
		 
	
				
			 
	 
 
		