A local business has the main duct plenums for return and supply located outside going to an RTU furnace/AC on the ground. Two trunks around 10ft. They are insulated on the inside but does not look to be the best done job. And, NO it is not possible to move the systems inside at the moment. They are planning an addition in a yr or two and would like a temp solution. It is in Iowa, in a heating and cooling climate.
How do I insulate the system better. I would like to spray foam the outside of the duct work with a closed cell product.
Does anyone know of a good working product that is UV rated? Or, is it best to just paint over top?