Why should I avoid a mini split?

In reply to Purple Frog :

There are countries where they wouldn't even think of installing central ducted systems. Mini splits are completely normal. 

Purple Frog said:

I didn't realize they had a cleaning requirement.  I need to research that more.  never thought about it... do they have filters inside?

Mine has a filter and it is quite simple to clean. The remote on mine tells me to clean the filter every so often, not sure how the interval is determined though.

SV reX said:

In reply to prodarwin :

There is also thermal loss through every joint and every foot of ducting (which is frequently run in unconditioned space)

Mini splits don't have that problem. 

Yep.  

*pedant mode*:  Actually, they DO have that problem, but in a different way.  They are moving the energy in refrigerant form, which is much easier to pump & insulate, and they aren't moving it is far.

Similarly with the fan, they are blowing air around, but not nearly as far.

In reply to prodarwin :

Right.  Ducted systems have refrigerant lines too. (Bigger and longer)
 

Refridgerant lines can be insulated easily, and they are also usually located largely inside the conditioned space. 

I've designed several houses in the Bahamas and they all use multiple mini-splits. I don't like them for the way they look inside, but that's my problem - they work great and can't be beat for ease of installation. I'm too lazy to look it up, but I bet the US is the center of the Earth for ducted systems. It's just what we're used to. 

Ceiling cassettes are where it's at. 

I suspect in the future that'll be the predominant installation method. 

Pioneer has some ceiling cassettes that allow for a single auxiliary duct, so you could cool a central hallway but put a little extra into a bathroom if necessary. 

 

In reply to pheller :

Yes, now they are making ceiling cassettes that go between 16" OC joists, whereas the older units require that the opening be headed out. They still aren't anything great to look at, but at least they only protrude into the room an inch or so. They also have built-in condensation pumps. 

In reply to pheller :

It looks like several manufacturers have that, but the static pressure is so low that they really won't push many CFMs

In reply to SV reX :

Nope! They come precharged. You have to vacuum it down to 500 microns Hg and then open an internal valve to release the refrigerant. 

I love the ceiling cassette idea, but it may not work for my application.  The flip house is trusses 24" oc (which is probably fine), but the addition is open web 2x4 flat trusses 16" oc.  That means there is only 12.5" between the trusses, and heading them off is not an option.

I'd KISS. One unit, one wall-wart head that's big enough, and short enough lines that you don't need additional refrigerant. It might take a few tries with cardboard to mock up an installation you like before buying it. The 30+ SEER units are just as reliable as the lower-efficiency ones, they mostly make their gains by having a larger outdoor unit. 

Condensation control is probably the biggest annoyance with them.  You are condensing the moisture in the air in the room in the unit.  It has to go somewhere.   With a central unit that is happening at the air handler usually in a utility room with easier drain options then finished spaces.

For commercial use the lack of outside air is a concern with them but residential central HVAC seems to pride themselves on a lack of outside air so it's not really an issue.   

I work with guys that do side AC work and they love the things for things like garages and single room additions.   They install ducted systems when there is more then a few rooms.  But we have winter here and winter becomes a challenge for all but the best heat pump mini splits.   Natural gas heating is a huge advantage of central AC when heat is a concern.  You obviously don't have that issue.  

They have bought their mini splits from highseer.com but have had good luck with daiken and Mitsubishi as well.  

They buy central units from local supply houses as they can get them wholesale.

Slippery said:

In reply to alphahotel :

Does your mini split have a filter on it?

The mini splits I have owned/seen all have a plastic mesh filter, like a window A/C or dehumidifier.  It wraps around the evaporator coil to filter the air coming in.  It is supposed to be cleaned every 2 weeks, and is easy to get out, rinse off, and put back in.  But it doesn't seem to do much.

My FIL almost came to blows (I may be exaggerating slightly) with the guy who put in his mini-split when it stopped blowing effectively a relatively short time after it was installed.  My FIL is a by-the-book kind of guy, so he had been cleaning the input filter every two weeks on the dot, and the HVAC guy suggested that his fan was clogged up because he hadn't cleaned the filter.

Watch for the condensing units lower ambient temperature operating conditions as it relates to your local winter time lows. You may need to supplement with some baseboard heat.

I'm in a spot in Central Valley, Ca. AC died a few weeks back- six quotes and no one will consider a mini split install. Our current unit doesn't cool the house evenly, and the main time we want cool air is upstairs and at night. I'm going to go ahead and buy a Mitsubishi 3 head system with ceiling cassettes (~$6k) at build.com and put one in each of the upstairs bedrooms with the intent of doing the same downstairs. I love the idea of not having to cool places that you aren't in, and I love the idea of something like 20seer minimum vs the best they were going to install as a central unit at 16 seer max. Combine the better seer rating with just cooling and heating the zones you need and I think I'll save a ton. 

We have LG ceiling cassettes in the firehouse. It's basically two separate systems with two base units outside, and each base unit controls its own two cassettes. 
 

One system controls two cassettes on opposite ends of a very large room. The other controls two cassettes, but each is in its own smaller room. 
 

We run into problems, especially in spring and fall, because we often have one group of guys who like their area to be very warm, while the other group of guys prefer their space to be much cooler. Both units on a common circuit need to be in the same mode (heat or cool) or they will trip the outside breaker. I could foresee this being a constant problem with an Air B&B rental. 
 

They also get very dirty, and subsequently noisy. They probably need to be cleaned several times per year. Unfortunately in our case, we can't touch them ourselves, because our employer (the city) also has dedicated HVAC crews who must be called in to work on the system. Last month, we were calling them in 2-3 times per week, until they finally called in a rep from the manufacturer. 

If you have a single outside unit with 2 inside they both need to be on the same mode in order to work. Both on cool, or both on heat. Both on auto does not work since one could want to cool and one heat, and that's not possible. 

I would do the mini split without a doubt. 

In reply to Woody (Forum Supportum) :

Unlikely that either of these properties will ever be an AirBnB.

 Our house was built with wood heat and someone added electric baseboard heaters at some point. There was never any consideration for AC. I looked into adding ductwork and a central furnace but quickly ruled it out due to cost. I ended up going with a pair of minisplit heat pumps. They work like magic. I had an issue with a schrader valve leaking in one and had to have it topped up. The HVAC guy charged us $750. After that I bought the gauges, a vacuum pump and a 20lb tank of R410a. Total under $600. I've since installed a heat pump in the main floor of my shop and will be installing another one for the second floor. If you can flair a brake line you can install a mini split system.

Just as a further point of interest. The mini split in my shop was salvaged from a construction project where it was used to provide heating and cooling for the site office. I had to buy some 3/8" and 1/4" copper line and insulation.  The unit is only 13,000 Btu so not really large enough to cool my shop completely but it cuts the humidity. As an experiment I ran the condensate into a 5 gallon jug and it was overflowing in just over an hour.

Doing one of these in the garage as I'm tire of freezing my butt off and they seem to be the safer less kill me option to many other things.  Having the AC option in the summer was the kicker for me.  Haven't pulled the trigger yet but it's on the list.