[784caroline]

You may want to get another AC recommendation. Wey=ther your existing ac unit can handle the additional space is very important for comfort. Check the size of your unit it should read something like 30XXX, 36XXX or 42XXXX and then compare it to your neighbors house of the same size.

Then you have to consider in terms of what you are doing, ie what type of glas will you be using (low e insulated or plain), direction of total sun exposure with emphasis on western sun, and sq footage addded. The county made my contractor do what they called a heating and ac SURVEY, Mums did it ($150). Also make certain the new AC/heat ducts are connected direcly to the furnace not simply an extension of the closest duct outlet.

We added 400 SF and did not have to change out or add to our heat/AC system but we had 1/2 ton more capacity than our neigbors when built for we had a slight (new build) expansion.

[batman911]

Another thing to consider is that if you get a lot of sun in the added space (with lots of windows) you should compute the total heat load you are adding, not just the SF.

[TarotJames]

I found several solutions to my questions about cooling our lanai. I joined Angies List and then searched for an A rated air conditioning company from the Angies List web site. Sunshine Air Condititoning sent a salesperson to our home and he gave us several solutions to heat and humidty on our lanai. Very reputable company and did not try to sell us high priced work we don't need. Thank you Villagers for all of the comments and experiences we found in the quick reply section. It looks like we will be purchasing a portable air conditioner to help cool our lanai.