We have been using Super Seal products on HVAC systems for at least eight years now and we’ve put it in everything from a 25-ton package unit on top of the post office, to most recently a 40-ton chiller we were working on obviously on another roof top. It’s a good product. It won’t fix huge leaks, but if you use it the way it was designed it will do a good job for you and solve a lot of problems.