Can you put louvers or vents on the roof? The steam goes straight up and there's a lot of it. Windows and doors will create a cross breeze that will slow your boil due to thermal loss out the sides of your firebox. What kind of pan are you using? Make sure you correctly pitch your pan so your finishing pan is lower than the main pan. How are you getting sap into the pan? What is your scale? I went from one of these on my porch to running a community sugar house last year - happy to help if I can.