We recommend venting the unit out a window using the provided window vent template and 4″ ducting that can be cut down to the required size. If no window is available, the second best option is to cut a hole in the wall. This may seem drastic but even if you hired a contractor to perform the work for you, the cost will be negligible relative to the cost of air filters over time if you aren’t able to vent the unit.
Filtration systems are available. Expect to pay $250+ monthly in replacement filters depending on usage and materials being cut. If you can vent it, do it!!!