Mini Split A/C systems

[Jlblake]

Good morning everyone!

Have any of you installed mini-split, ductless a/c systems?

The home I recently bought has had the attic converted to living space. The upstairs is around 850 square feet. The previous owner has one (old) window unit to cool the area. I don't like window units and I want the windows closed/sealed up. The A/C guy that came out last week crawled under the home (pier & beam of course) and showed me that the current duct work is not accessible to the rear of the home. His suggestion was a mini-split system...two of them actually...one for the bedroom and one for the office area upstairs.

Ductless Mini-Split Systems - AC & Heating | AlpineHomeAir.com

Do any of you know much about these? Total cost for installation, some new required electrical work is around $4k. That's 12k in one room and 9k in the other...seer rating is 19/18.

Thank you!

 

[TnAndy]

I have two of them in my house, both self installed, love them Very quiet, electrically stingy, great units.

Biggest issue is running/hiding the line sets/drain. One of mine I ran across an attic space, the other comes thru a basement wall and up inside a closet wall, the unit is over the top of the closet doors facing out into the bedroom. I have another unit bought waiting on a bathroom remodel this fall, while the bathroom wall is gutted, I'll run the lines up that wall to the bedroom over the 1st floor bath.

You can do much better on the SEER rating than 18/19. The Mitsubishi 12k unit in my bedroom is 23 SEER.

 

[Jlblake]

I have two of them in my house, both self installed, love them Very quiet, electrically stingy, great units.

Biggest issue is running/hiding the line sets/drain. One of mine I ran across an attic space, the other comes thru a basement wall and up inside a closet wall, the unit is over the top of the closet doors facing out into the bedroom. I have another unit bought waiting on a bathroom remodel this fall, while the bathroom wall is gutted, I'll run the lines up that wall to the bedroom over the 1st floor bath.

You can do much better on the SEER rating than 18/19. The Mitsubishi 12k unit in my bedroom is 23 SEER.

Thanks for the insight.

 

[dalola]

I can't offer you much detail, other than a friend who has one in his office (it's a separate garage-type structure on his property), and is very happy with it. The few times I've been in, you can barely hear it run, and it's always a comfortable temp inside.

In the right situation, I would give it a good look for sure.

 

[LouNY]

A couple of years ago I had two large mini-splits installed in my home.
There are two 36,000 BTU out door units each of those feeds four independent heads through out the house.
The installers had to work a little as all the lines enter the basement then travel to beneath a closet then up to interior walls in the house.
The cost was actually more then installing a central air unit would have been but of all the contractors that came out every single one wanted to put every thing in the attic and just run flex ducts to the individual rooms with a single thermostat for the entire house. In this air it gets very humid when it's hot and too many people I knew had moisture (condensation) issues with the flex duct in the attic.

None of them wanted to talk about individual room t-stats and powered dampeners so different areas could be set different, or even not be air conditioned if not in use.
Then a couple had the audacity to complain when I didn't pick there system because it was cheaper.

My electric bill has gone down for the summer with several window units replaced by these two large multi-splits,
and they do a decent job of heating in the fall when the temperture swing a lot day to day or week.

 

[3Ts]

We have an 805 sq ft cabin that we built and lived in for a couple years. It is much better insulated than normal for this area so I did all the BTU calculations and the installation with some help from my wife. The hardest thing to do is to get the indoor unit up on the wall while sticking the stub lines thru a 3" hole. (We were in our mid 60's at the time). You'll need to run power to the outside unit. The power for the inside comes from the outside unit and can run in the same chase as the refrigerant lines. We bought our unit on-line from Supply House. I can recommend them, they've done well for me.

The most important thing is to draw the vacuum below 300 microns! Use a small vacuum pump and a digital pressure gauge. Plan on running the pump all day. Even if the vacuum drops below 300 after an hour, keep the vacuum on it all day. In this case, slow is better. If your lineset is more or less than 25' you'll need to adjust the amount of freon. I made sure to use exactly 25'. It has been running almost 6 years now and the only repair has been a fan bearing on the inside unit that was getting noisy. As for maintenance, it's been trouble free although getting to the filters at the top of the inside unit requires a short ladder for us. Think about how you'll get to it for maintenance, we installed ours over the washer & dryer so we have to move those out to get to the A/C inside unit.

 

[ustmd]

Like you, I am in Central TX and did an attic conversion. I put in a mini spilt and love it. If I did not already have a traditional duct system in the rest of the house, I would convert everything to it.

The system is quiet, effective and cheap to run. $4K installed for 2 systems is not bad.

There are Mr Cool units that are DIY systems with lines that are already evacuated. The New MRCOOL DIY Is Engineered For Comfort

 

[Jlblake]

We have an 805 sq ft cabin that we built and lived in for a couple years. It is much better insulated than normal for this area so I did all the BTU calculations and the installation with some help from my wife. The hardest thing to do is to get the indoor unit up on the wall while sticking the stub lines thru a 3" hole. (We were in our mid 60's at the time). You'll need to run power to the outside unit. The power for the inside comes from the outside unit and can run in the same chase as the refrigerant lines. We bought our unit on-line from Supply House. I can recommend them, they've done well for me.

The most important thing is to draw the vacuum below 300 microns! Use a small vacuum pump and a digital pressure gauge. Plan on running the pump all day. Even if the vacuum drops below 300 after an hour, keep the vacuum on it all day. In this case, slow is better. If your lineset is more or less than 25' you'll need to adjust the amount of freon. I made sure to use exactly 25'. It has been running almost 6 years now and the only repair has been a fan bearing on the inside unit that was getting noisy. As for maintenance, it's been trouble free although getting to the filters at the top of the inside unit requires a short ladder for us. Think about how you'll get to it for maintenance, we installed ours over the washer & dryer so we have to move those out to get to the A/C inside unit.

Thank you, great information. I have an HVAC guy installing it.

 

[Jlblake]

Like you, I am in Central TX and did an attic conversion. I put in a mini spilt and love it. If I did not already have a traditional duct system in the rest of the house, I would convert everything to it.

The system is quiet, effective and cheap to run. $4K installed for 2 systems is not bad.

There are Mr Cool units that are DIY systems with lines that are already evacuated. The New MRCOOL DIY Is Engineered For Comfort

Thanks. Great to know yours has worked out well.

 

[Lineman North Florida]

I built an 800 square foot hunting camp and installed an 18k Mr Cool DIY unit myself and it has been fantastic , I have less than $1500.00 in everything and it was pretty simple to install , I would have never believed how quiet and energy efficient they are , I don't think you will be disappointed.

 

[robstaples]

I have 4 Fujitsu high pump units and all are inverter based and the Two 9000 btu are SEER 33. The inverter based units have about 99 steps of power from low to high so when not at full power the outside heat exchanger has a relative larger area and the efficiency goes up as the unit slows down. There is a limit on piping length. Like 40 ft. Not sure why. Very quiet and comfortable.

 

[milkman636]

I have installed two mini-split units in my home as well. They've been purring along for 5 years now and doing great job. They solved the window shaker problem in my house that has baseboard heating and no ductwork. The 12 k btu units run on 15 Amp circuits and use a 1/4" and 3/8" copper tube for refrigerant lines and a 3/4" plastic drain tube. The whole insulated bundle of tubing will fit through a 2" PVC pipe to sleeve the hole to the outdoor unit. Efficiency is very good, and they will provide both heating and cooling if you are getting a heat pump model that is equipped with a reversing valve. The 2 units with wall brackets, line sets, disconnects, and wiring would probably set you back slightly above 2k just for the equipment. A good flaring tool and a vacuum pump would also be needed. Its also a good idea to perform a standing pressure test on the tubing with nitrogen before pulling the vacuum and opening the service valves to charge the line set. So from my perspective it sounds like you are getting solid advice and the pricing seems fair.

 

[hslogger]

I live in western Oregon. I heated with wood exclusively until about six years ago. We went Mitsubishi and hired the install from a local outfit. House has two outside units, inside has three units first floor, one unit second floor.

Separate building has one unit in and out. We are pleased as we can be with all of them. The real key is the installer and their reputation for not mickey mousing the job.

 

[spitter]

They are used constantly in commercial buildings in server rooms and any where you need more ac.:drink:

 

[Bocephous]

I had a Fujitsu 15K BTU single zone unit that cools and heats installed a couple of months ago in our smallish (1000-1100 s.f.) ranch home. It is quiet and does a good job of keeping the main living area cool. Installation took half a day, and total cost was $3300. I don't know about the cost savings yet vs. our old 12K window unit, but I am optimistic after hearing others claims of efficiency.

 

[EddieWalker]

I don't have one. My house is all done with a conventional AC system with duct work in the attic and at least one vent in each room, some with 3 vents. My house is very comfortable.

As a contractor, I'm in a lot of different houses every week. Sometimes to just look at a project and give them a bid, other times to work on a project for the client. I'm guessing that I've been in half a dozen homes with mini split AC systems. Some smaller homes use them exclusively, other bigger homes use them for added on space or converted space.

In every case, when I walk into those homes, or those rooms, they feel more humid and uncomfortable compared to more traditional AC homes. They are better then nothing, and maybe cheaper to run than a window unit, but if I wanted to make a room comfortable and didn't want to, or have the option of running ducts, I would rather have a window unit. Granted, they are ugly, noisy and suck up electricity, but they work great at cooling off a room.

 

[Jlblake]

I built an 800 square foot hunting camp and installed an 18k Mr Cool DIY unit myself and it has been fantastic , I have less than $1500.00 in everything and it was pretty simple to install , I would have never believed how quiet and energy efficient they are , I don't think you will be disappointed.

Thanks. The unit costs were really low, it's the labor that's costing me. I'm happy to pay that because I would definitely screw something up with a project like this. Glad to know you're happy with your system!

 

[RalphVa]

Don't know why he says you need 2. One outside unit can serve up to around 7 inside units. Just route the refrigerant to separate inside unit controls and size as required. We've 1 outside unit serving 2 units here in the basement. This is after I shivered and shaked for 2 months or so while recovering from congestive heart failure in early 2013. Had space heaters then. Think we installed these Fujitsu units later that year. Just have to clean the filters on the inside controllers about every 3 months or so. Otherwise, no service. Quietest and most efficient units we have. No backup heat coil like in a ducted system.

Ralph

 

[newbury]

I had a Fujitsu 15K BTU single zone unit that cools and heats installed a couple of months ago in our smallish (1000-1100 s.f.) ranch home. It is quiet and does a good job of keeping the main living area cool. Installation took half a day, and total cost was $3300. I don't know about the cost savings yet vs. our old 12K window unit, but I am optimistic after hearing others claims of efficiency.

When I read installation cost of $3300 and compare price for a 15K window unit, about $500, I wonder how long one would have to run it with electricity cost like mine, 10 cents/KwH, to save money.
For $2K I can buy a lot of electricity.

 

[riptides]

I have got a slim line Mitsubishi unit in our pool house. The building sits in the sun all day and the front is mostly glass doors. So the afternoon sun and water reflection make that buildings inside feel as though your under a magnifying glass.

Prior to that we had a window a/c unit, that was temp until the Slim Line came in. Even in the middle window of the back side, it could not keep up.

With the Mitsubishi, we also get the added benefit of using the pool house in the winter.

I don't notice the unit on the electric bill, and once a "nice" temp is reached, I don't notice the unit working. Seems now, all my other houses A/C centralized units are running all the time.

I like the look, I like the feel, I liked the installation, and it seems we did a right choice for that building.