I experimented w/ a 9K single hose. About 18" duct. 90F+ ambient. Could touch duct but WAY too hot to grasp n hold. No temp taken. So the entire duct was radiating into the cab. Unit could only give about 10 degree delta so scraped that idea. No interest in insulating duct because the unit plus a fat tube was too much real estate to sacrifice.Do people really have experience with hot exhaust tubes or are we just speculating? I run one of these in my house constantly and I have never once felt the exhaust tube/area be hot or radiating.