I like mini splits. My concern is the ability to distribute conditioned air to all of the living spaces in your home--especially the baths-- with a limited number of cassettes.

Maintenance chores will wear you out with mini splits as they age.

4 heads = lots of headaches. It would be natural for a builder to like mini splits... they aren't there to maintain them when they break. After about a year or two builders are building somewhere else.

Then there are the rooms that don't have any heads. That doesn't sound comfortable to me.

In *some* situations mini splits are good choices, but I would think long and hard on that as a whole home solution.

To be sure, selecting the best HVAC system for a particular application needs to consider a number of variables including maintenance.

I'm not aware of any studies of the long-term reliability of mini-split heat pumps compared with conventional heat pumps. The majority of information on longevity is from HVAC contractors--not controlled studies, so it's not without bias. I would expect the useful service life of a mini-split system with proper periodic maintenance to be comparable or better to that of a conventional heat pump since their inverter control eliminates compressor hard starts and the stress of on/off operation of most conventional heat pumps.

"I was thinking of going with a 36k multi-zone: 9k-9k-9k-18k."

Math check - this totals 45k. 45k on the cooling side is nearly 4 tons, perhaps too much for a split system but fine for a modulating minisplit.

Central/split systems for AC are most common in North America and rare elsewhere. Minisplits are all you see for cooling throughout Asia and Mediterranean Europe/Middle East areas. For a variety of reasons, not the least of which it's the easiest retrofit for older (often masonry) buildings when adding AC.

The OP doesn't mention the location nor if the system is just for cooling or cooling and heating.

Thanks. 9-9-9-18 -> 36k is an available MrCool DIY package.

Climate is coastal California.

I suspect the mini splits will be used for a couple weeks in winter & summer

I'm not aware of any studies of the long-term reliability of mini-split heat pumps compared with conventional heat pumps.

Studies? LOL. I spend all summer long going and repairing HVAC systems. Those HVAC systems probably average anywhere from 3-8 years old, some older... some younger.

The more moving parts... (4 heads remember) --- what happens? There's your study. ha-ha-ha-ha.

Convential systems will break too, there is no escaping that --- except for mimimalizing it. You don't do that with a multi zone, multi head mini split.

@Austin Air Companie

Ray,

If you're willing to entertain an alternative viewpoint from a HVAC contractor in Arizona, here's a link to their take on mini-splits:

https://www.airconditioningarizona.com/how-long-do-mini-split-ductless-air-conditioners-last/

They estimate a 20-year life expectancy for a mini-split versus 12-15 years for a conventional system in their climate zone. It's not a controlled study, but they make a good case for the extended life expectancy. They're a large firm, and would be expected to encounter more service requests than a one-person replacement contractor like you. That makes their experience database larger and, in my opinion, more credible with respect to the assessment of mini-split reliability.

Does this condo have existing heating and cooling? The 4 head 36K BTU Mr. Cool mini split is $3550 in Home Depot. Are you planning to install this yourself?

If you only need heating and cooling a couple weeks in the summer and winter have you considered using electric baseboard heaters and window AC units? It would be a lot less money and very easy installation. In response to your original question, it does seem like overkill for the location.

mike, the OP hasn't specified the exact location, nature or intended use of the property, nor the spending budget, but you can't go further down-market around here than the vibe communicated by electric baseboard heaters and window AC units. Especially if the property is not located in one of the few municipal electricity areas with reasonable rates, like LA City, the cost to operate electrical resistance heating is a big negative. I'll go so far as to say that anything other than central, split systems is rarely seen in new construction. Construction is expensive, home values are high, and this isn't a place for a developer or owner/builder to try to save money.

For down market structures like a small extra granny flat or rental unit in a backyard, perhaps a vented gas wall furnace and a window AC unit might pass. Not in a new, middle class home. Spending a few extra thousand dollars to have something more "common and familiar" would more than pay off. As for my reaction to the DIY aspect of an install, I'll withhold comment.

They estimate a 20-year life expectancy for a mini-split versus 12-15 years for a conventional system in their climate zone. It's not a controlled study, but they make a good case for the extended life expectancy.

How many repairs to that system in that time frame? An HVAC contractor issuing an opinion is often fraught with enriching said contractor. Someone "selling you" is more interested in "selling" than anything else. That does little for you in the scope of an estimated 20 year life.

It doesn't take long for "most people" to understand they are being sold and not in a good way.

I tell it like it is, 9 times out of 10 you're not going to like what I have to say. Anything out side of that is a gimmick or bold faced lie --- You choose the verbage you like ___________________.

I posted a video before of a HVAC brother in arms of mine in the UK that services alot of this type of 'mini split' equipment showing one after the other of broken mini splits.

Would you like to see that video again? I know you're easily sold Charles, but most people I know aren't like you or any of your friends. LOL. Big smiles and a mild chuckle.

The life expectancy of any system is a function of the manufactured quality of the components, as well as the quality of the installation, how it's operated and how it's maintained. The experience base of a larger HVAC contractor compared with a one-man company provides a much larger database. They make a credible case for mini-splits, albeit their finding is different from yours. Houzzers can judge for themselves.

Elmer,

Normally I wouldn't recommend baseboard heating. I also agree window units are looked down as an acceptable cooling solution. Given the small amount of information I was trying to propose an alternate solution. The original author stated this is a new design. Does this mean new construction or a new design of an HVAC system for an existing property? I also got the impression the goal was to find a DIY solution which was another reason for my suggestion.

It doesn't hurt to offer constructive suggestions and let the original author decide what is best for their situation.

The experience base of a larger HVAC contractor compared with a one-man company provides a much larger database.

It's not uncommon for me to get new customers from larger HVAC companies.

How much experience could someone really have running calls for a company not their own, 20-30 something year old?

How long would it take for someone to *feel* like they are getting taken for an unpleasant ride with a larger HVAC company? A different face servicing their equipment? A one man company -- you always know who is coming. Yes! You have a choice.

The HVAC business is beyond hard for a variety of reasons. Look at the guff I alone get from certain people here. That's less than half of what you do see.

*Experience* is what tells me not many will succeed at a job like this, among other things. I am unique --- people search for me. I just leave bread crumbs so they can find me.

I service the Katy, Texas area.

@Austin Air Companie,

Your claim regarding the life expectancy of mini-splits based on your experience is no more or less credible than any other HVAC contractor who has serviced an equivalent number of units. I believe the vast majority of your work is servicing conventional heat pumps and air conditioners not mini splits. Houzzers would be well served to know how many mini-splits you've serviced over what time period to calibrate your claim regarding their life expectancy.

Houzzers would be well served to know how many mini-splits you've serviced over what time period...

Currently over 27 years in HVAC, 14 years running and operating my own company. In terms of numbers it doesn't matter... in my climate typical normal life expectancy average is 10.5 years to 12 years regardless of brand. That is the "rough" average life due primarily to "use" --- Using air conditioning 9 -10 months per year every year? Some units may breach 15-18 years of use but not that common today... the longest? Around 30 years or so... but what we're talking about in that "age" of HVAC doesn't exist in "today's" world in my opinion. Mini split doesn't solve that either.

The more equipment you have, the more it costs to maintain. The more you use it? It's not rocket science as you say Charles.