Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

Does anyone have the ductless split AC systems offered by Mitsubishi, etc.? Is installing them a DIY job? Can you share your comments about them, in general?

Edit: Inspired by DA01 comment, I'd like to add:

From what I see in NE US, they don't seem that popular. Few installers deal with them and all the quotes were higher than conventional systems. Why would this be?

Also if they are so popular why doesn't anyone comment on them here?

share|improve this question
1  
I don't have them but have been keeping an eye on them. They seems very popular. I've read that short of charging the system, it can be a DIY install as it's mainly just running flexible copper via small holes in the walls. –  DA01 Apr 20 '11 at 15:04
    
Hm, popular? Yes, in Europe and Japan but in the US? –  Peter Q Apr 26 '11 at 17:21
1  
Well, popular is relative, but in MN I'm seeing more of them. Maybe it's our humid summers combined with lots of hydronic heating systems. I see a lot of them in small businesses around here. –  DA01 Apr 26 '11 at 19:32
    
So you think this can be done as DIY? I'm actually OK with someone taking care of the installation but they are asking for too much money. –  Peter Q Apr 27 '11 at 3:33
1  
I don't know a whole lot, but from a little bit of reading and an episode of This Old House, it seems doable. Pour a slab for the condenser, mount the interior portion on a while, drill some holes, pull copper and wiring. The only potentially tricky part appears to be charging the system. –  DA01 Apr 27 '11 at 13:59
show 2 more comments

1 Answer

Mitsubishi Mr. Slim is the most common example of such a system. I have seen them in several places out west, but not so much in the eastern US. They are very popular in Japan, and other Pacific countries (notice the band names of most of the systems), but they are just starting to become common in the US.

As I understand it, these systems became popular in urban settings because of high-rise buildings. It is easier to route coolant lines down from the rooftop instead of massive central air ducts.

If you are retrofitting a house that doesn't have existing ductwork, these mini-split systems can be a preferable option. As any HVAC contactor can tell you, designing ducts for proper airflow can be a difficult task, and it can be almost impossible to get right in existing construction.

If you get one of the multi-zone ductless systems, you have a thermostat at each indoor unit, which can allow for more flexibility in setting different rooms to different temperatures.

They generally have very high efficiency ratings. In many cases, they have a higher SEER/EER than an equivalent centralized AC system.

The drawbacks to these systems are:

  1. You have the indoor unit sticking out from the wall.

  2. Since they are less popular, it can be harder to find a competant service company.

  3. Fewer companies selling/servicing mean it can be more expensive to get work done.

  4. The residental systems I have seen can support at most 3 indoor units. So, if you want good airflow in every room of your house, you're not going to get it.

  5. The residential systems I have seen max out at ~3.5 tons of total cooling. So, a single system may be insufficient for a big (or poorly insulated) house.

I have a relative who converted his screened-in patio into a sun room. He then added a Mr. Slim to provide A/C. It's quiet and keeps the room cool. And since it is independent from the main house HVAC, the whole house doesn't need the A/C running constantly. This seems to be a really good fit.

At my office, we have one of these units installed in our server room at the office to provide cooling. We've had several problems, but I think the unit was undersized for the application. It's also a residental unit that wasn't made to cool a server room 24/7/365. It's quiet though.

I don't have any first hand experience with the heat pump version of the unit, so I am not sure how well they do in a heating scenario.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.