I recently added a 400 sq ft room addition (basically a really big sunroom with windows on 3 sides and a cathedral type ceiling -- 4th wall is against my garage.) I've been told that my AC / Furnace can handle the extra space, but the duct work can't and therefore the room is typically 5-10 degrees off the rest of the house (too hot in summer and too cold in winter.) As a point of refernece, it's a 2,600 sq ft ranch house on a slab. The thermostat is on the opposite end of the house from the room addition as is the furnace which is up in the attic.
My current furnace / AC have another 10-15 years on them and I've been told the solution to making the room addition more comfortable is to either zone the house (3 zones) or add a mini-split ductless system.
I've gotten 4 estimates, and 2 of them are really pushing the mini-split. One of the other two told me that the mini-splits weren't really up to code anymore nor do they meet government standards and that they are probably being pushed in order to get rid of existing inventory.
Not sure who to believe as all four estimates / recommendations have come from reliable (no BBB complaints and recommended by friends) companies.
Any advice would be appreciated in regards to the code/standard issue on the ductless system, and which option would be better from an energy efficiency / best investment / keeping the room comfortable perspective?
Many thanks for your help,