The a little over $11,000 price includes a Mitsubishi MZX-4B36NA Condenser, a MSZ-GE24NA AND A MSZ-GEI5NA Air handlers mounted to walls. All related piping and wire run to electrical circuit. A condenser pad and strapping to it as well.
That's a still a little on the high side, but if it comes with a 12 year warranty, that's pretty darn good.
Have you looked at other options, such as using two independent mini-split systems, instead of one combined unit? For example, one 18,000 BTU unit in each room if they are the same size and have the same occupancy, or maybe one 24,000 BTU system for the larger room/highest occupancy and a 12,000 BTU system for the smaller room/lowest occupancy, or some such combination? It might work out cheaper overall.
I do not have a provision for adding fresh air though.
Ummm.... you need it. It's not "something that is nice to have": rather it is "somthing that you absolutely must have". You see, people have this terrible habit: they like to breathe. They really very much want to inhale lots of Oxygen, and then they really like to exhale lots of carbon dioxide (and other nasty stuff). With no ventilation, the people in your room will use up all the O2, and replace it with CO2. It can get unpleasant in there quite fast, if you have a few people jamming hard...
Studios are not like normal rooms in a normal house, where there are numerous leaky paths for air to enter, and the doors are usually open most of the time. Studios have no leaky paths: they are sealed absolutely air-tight, twice over, with high precision, and the doors are always closed. That's the way it HAS to be to get good isolation and proper acoustics. There is no path at all for air to get in or out.
So here's the thing: If you like breathing and staying conscious, you absolutely unequivocally do need ventilation.
Your room probably won't even pass inspection if you don't have it. There are legal code requirements about this. ASHRAE and code specify at least 6 room changes per hour for most rooms, and 8 is better. Some rooms require as much as 12 or even more. So calculate the volume of your room, multiply by 6, and that's how much air you need to move through the room, every hour.
The dimensions are 13' x 18' with a 11' ceiling.
2,574 cubic feet x 6 = 15,444 cubic feet per hour. Most fans are rated in cubic feet er minute, not per hour, so divide by 60: 257 CFM. You need a duct and fan system that can move about 250 cubic feet per minute of air through your room.
This is not an option.
As of now, I'm planning on just opening the outside door periodically inbetween sessions.
That wont work. As I mentioned above, there are no leaky paths into your room, so opening the door does nothing. In order for the air to move, you need to give it a reason to move! You need to have a pressure differential between two points. Opening the door only provides one point, and no difference in pressure. You need to create that pressure differential with two HVAC ducts: one of them brings fresh air into the room, the other takes tale air out of the room.
I know this isn't ideal,
Not only is not not ideal, it just plain won't work. Look around the forum, and you'll find a few threads where people thought the same way you are thinking, and built their rooms like that. Then realized what a huge mistake they made afterwards, and had to go back and install proper HVAC.
but in my case, it is probably better
Nope. Sorry. It just isn't. In fact, it's not that it "isn't better", but rather that it just isn't an option.
I really don't have much more room between the live room walls to make the necessary bends in anything other than maybe a 2" pipe at most in the 4" between the walls.
Then you'll need to change that! fortunately, you are still at a point where you can do that, with relatively little pain. There is no drywall yet, only framing, so you can easily modify the framing as necessary to get your ducts and silencers in.
Any ideas?
Yep! See above...
In other words, stop building now, figure out how to get ducts and silencers boxes in there to supply each room with 250 CFM at less than 300 FPM, modify the framing as needed for that, then after that is done, carry on building.
- Stuart -