I am thinking of adding a preheater to our 3x10 king that was new last spring. I'm not sure if this will pay for itself or even come close. Some friends claim they work great and raise sap temp to 180 or higher. Others are not nearly as happy with the results. Also we would need to remove preheater for a few days when we do group tours and the hood blocks to much of what is happening in the evaporator. Does anyone remove theirs and reinstall during the season? Also we are wood fired and will be using forced draft.