The vacuum hose coming out of the motor through the ceiling kept unraveling I had to change it several times also hose in attic kept blowing off I switched to a heavy duty 2 inch hose similar to what a septic tank pumper uses and used extra hose clamps that fixed it also had to put an attic fan at one end of my building to try to keep the temperature down the air coming out after about 4 to 5 minutes of usage was 150°. My outside dryers in the bay out of the sun the temperature is still gonna get 130°. But I have no issues at that temperature. I feel like you put them on your flat roof. The sun is going to directly hit them and you’ll probably get the same temperature that I was getting on the ones in my attic. If you need me to send some pictures, just let me know, but I believe you would definitely regret it if you put them on the roof.