I installed a Ronco tank a couple of years back. It came with one 1/2" threaded vent fitting on a side near the top and two 1.5" threaded fittings for inflow and outflow. I'd like to increase the size of the vent to 1", as recommended, and add another vent to the other side of the tank. My question is how to add another vent without adding an access panel to the top of the tank. Is there a way to thread a new fitting from the outside only? I don't know the thickness of the tank walls, unfortunately, but maybe someone out there has some knowledge/expertise at this?