Hello,

I'm finishing off a bonus room upstairs, which is roughly 370 sq ft (26 ft x14.5 ft). I'm planning on installing a mini-split system instead of tying into my existing heat/air system (don't think the furnace/AC is big enough). I'm not sure on what to go with in size, 12KBTU, 15KBTU or 18KBTU, any suggestions? I live in Oklahoma so the winter's are typically mild but the summers are mostly scorchers. I know heat rises so I'm not too worried about keeping warm, I'm more concerned with keeping it cool.
I have another question on where to mount it. The ceilings are built on a slope to follow the roof line so I have vertical walls that are about 4-5' high with the ceiling sloping up to 7' high and then it is straight across. What height and where in the room? The stairs will be open to the downstairs and they are on one end of the room, not in the middle.
Thanks.

Well, since there were no replies on the above question, I'll ask another one and see how that goes.
I bought a Mitsubishi, Mr. Slim mini split, 15KBTU, MUZA15NA with MSZA15NA. I'm going to mount the indoor unit about 4' off the floor just prior to where the ceiling starts to slope upwards. I need to install the outdoor unit as well as run about a 30' lineset, but I have NO experience with this. I got one ballpark quote of around $400 to install, but I'd like to save some money if I can.
I need some advice/direction on how to run the lineset and get it installed. I can run the electric without a problem and I shouldn't have a problem getting the line charged when the time comes. I was planning on running the lineset over my rafters, amidst the blown in insulation, through a hole in my soffit, down the outside of my house and then attach to the unit. The indoor unit I can connect when I get the drywall finished.
Any input is appreciated.
Thanks.

If it was me I would go with the 18000. Open stair way and a room against the roof line. The mini-split will run on at least 3 different fan speeds to give you some leadway. But it all goes back to the load calculation of the room. (windows,insulation in the walls, insulation in the ceiling.)

Could you tell me how much you paid for the MSZ-A15NA/ MUZ-A15NA?

Thanks!

Right around $1600. Factor in electrical, copper and installation on top of that.

You were ripped on the price of the unit to start with. WARNING!! Mini splits are not easy to install when it comes to the refrigerant lines since usually they need to be shortened and brazed with a acet/oxygen torch and # 15 silver braze rod. Next and most critical. They need to be vac down very carefully to not allow any contamination to remain in the system. You will also need a vac pump besides the torch and silver alloy. The next part requires a EPA certificate. Mini splits are a very critical charge piece of equipment. It will take a real pro with experience to charge the system correctly.

BTW do not forget to flow nitrogen in the refrigerant line when brazing. The capillaries on a mini split are very small and the flake that will for on the inside of the copper will plug it up unless you flow nitrogen to stop the flake from forming. Good luck.

Actually they are pretty easy to install. If you follow the instructions in the book they give you and it will be step by step. You can install it easy. The line set (freon lines) has flared ends on it so you do not have to make welds unless you need to extend it further. Get the line set when you order your system. Good luck with your project.

I was quoted $4000 for the MUZA15NA with MSZA15NA fully installed. Sounds like too much of a markup.

hvac1000

I don't think I got 'ripped' on the price to begin with. Let me know where I could have gotten one cheaper and I may agree with you. $250 or so cheaper is getting 'ripped' IMO.

I did all of the rough in on the unit, running the copper, drain and the electric and installing the wall mount. I had a guy come out and braze the connections, pressurize the system overnight, pump it down and then check the charge. The unit was blowing hot and cold air and works fine. He charged me $125. He's a heat/air instructor at a local Metro Tech.

Some quick guesstimates -
Copper - $100
Electrical - $150
Concrete - $60
Misc - $100

Roughly $2200 for unit and installation with me doing nearly all of the labor.

MSY-A15NA MITSUBISHI This model dealer direct cost to my old company is $ 1193.21 plus tax if applicable. This is direct wholesale from one of my old suppliers for my personal use. I am no longer in the HVAC biz but do teach augratis at NKU.

I called this AM since they are open till 12:00 noon on Saturdays. This is not the exact model you have but it is the heat pump style. This unit has many bells and whistles which I do not care for but they do not handle the cheaper unit so I could not get a price on that one.
This unit uses R-410 as a refrigerant.

There is a lot of mark up in this kind of equipment and that is why people like to sell them.

Thanks for all the information. One last question--- will this heat pump work when the temperatures are consistently around 0? I had one contrator tell me they work great in those conditions, and another tell me they're useless under 30 degrees. Can anyone speak from experience?

Zero is a little low in temperature for a HP to do much good. They will run you just will not get much heat.