There are a few things to check to ensure this doesn’t happen: Ensure that the hose is properly installed at both ends and this should minimize heat escape.Ensure the hose is not over extended. Keep the unit as close the window/patio as possible.Ensure the unit is in an area where it’s getting lots of air circulation, which allows the unit to run cooler and results in less heat escaping.If the heat is escaping from the exhaust port then the hose is either restricted or not installed properly.Unfortunately, it is not possible to completely stop all heat loss from escaping.