It seems like the best place to install the 12,000 BTU air conditioner in our house is in a window in the living room. On the other side of that window is an enclosed porch, approx 27×7 feet. Because the windows jut out into the room, there would be about 4-5 feet between the end of the AC and a window. Here's a diagram of the house. The porch is the lower part and the red is where the AC will go 
The online consensus seems to be that installing a window AC between two rooms like this is bad news but I'm wondering if it might be more useful in this situation since the porch has some airflow and the unit would be relatively close to a window. I have two main concerns: airflow and drainage.
Drainage seems relatively easy, as I could hook a hose up to the bottom of the unit and run the water right out a window.
Airflow seems the larger issue. Even though it's almost entirely windows, would the porch heat up so fast that it would ruin efficiency (and maybe the AC unit condenser)? And if that's the case, could I try to run a duct from the back of the AC to the window about four feet away? Would that make it feasible or should I just find another window?
Your thoughts? Thank you!
Best Answer
If you have a forced air furnace for heating, you could install the window unit in another window and run the furnace fan to circulate the conditioned air throughout the house. My son did this in his first house. As for using the window you mentioned, you could do it your way if you can insure good air flow in and out of the porch area to keep that area the same temperature as the outside. Window fan/fans, may be needed. If the porch area heats and has high humidity that will affect the operation of the A/C unit and could ruin the porch area. All window A/C units produce lots of heat and humidity when operating. So you will have to make sure you address these issues. A split system or other type of cooling unit would be preferred. Depending on where you live a 12,000 BTU unit may be a little undersized.