A Beginner Guide on Ductless Mini Split Air Conditioners


I bet you heard about the good and the bad things about ductless mini split air conditioners. Companies who are doing central air conditioning are recommending you not to get the ductless mini splits. Meanwhile, you’ve done some googling and found out that ductless mini split air conditioners are actually not bad.

Then, you came here and I’ll tell you everything about ductless mini splits.

Before I start, you need to know that ductless mini split air conditioners accounted for 77% of the world’s air conditioning system used as of 2016 (I bet hard now is even more). Globally, most people are using the ductless mini splits or what we called split system or split air conditioner (by default split ACs always are ductless, so we don’t add “ductless” and the “mini” I’m not sure why).

Read more about Do Mini Splits Heat and Cool?

In the United States, many people are still relying on the old ducts built together with the house. Meanwhile, many new houses in the world are not built with ducts because they will be too expensive to buy.

However, many people are getting into the mini splits. Just go to Reddit and see for yourself. The truth is mini split air conditioners are much better than central air conditioners and companies who are against ductless mini splits are probably due to business interest (I hope they don’t bomb me).

“Many people are getting into the mini splits.”

From my observations

I’m guessing the reason why ductless mini split air conditioners are so expensive to install is because of the labor cost and perhaps, lack of mini split installers which naturally inflate the price.

In countries like Malaysia, most split air conditioners installation is only 10% of the cost of the air conditioner itself. Meanwhile, I’ve seen people share about their mini splits installation cost in the United States which the cost is equal to that of the mini split itself, if not higher.

Nevertheless, as more people adopt the mini splits, the installation cost will eventually go down, so with the service, maintenance and part cost.

The Best Form of Air Conditioner

A ductless mini split consists of one indoor unit and one outdoor unit. Both units are connected by refrigerant pipes. The indoor unit required a drain pipe but not for the outdoor unit.

The indoor unit is usually hang up high on the wall so as the outdoor unit at the exterior wall. The indoor unit has many different types to choose from, each has its own unique application.

The best thing about ductless mini split air conditioners is simplicity. In engineering, simple is the key to low cost and long lifespan. A complex system means more things can go wrong.

Problem with Energy Loss

Central air conditioning systems rely on ducts to distribute air. Duct leakages are inevitable and even SMACNA (an international ductwork standard organization) stated that the allowable duct leakages are 2%. However, the duct in most homes is way more than that.

“In typical homes, about 20 to 30 percent of the air that moves through the duct system is lost due to leaks, holes, and poorly installed ducts.”

Energy Star

The reality is that ductwork is hard to construct and install. Do you know that workers are just using a hammer to join the ducts? Machines such as laser cutters and duct bending machines are used in the factory to produce 50% of the finished duct. The other 50% need to be hammered on site.

Thus, no matter how good the installer is, there will be some leakages that will drag down the overall efficiency of the air conditioning system. Yes, the central air conditioner by itself may have a higher energy rating but we need to see the overall efficiency which will directly reflect on your monthly electricity bill.

Initial Cost

Another good one I’ve seen about people who are pushing the central air conditioning system is that ductless mini split air conditioners are more expensive to buy than central air conditioners which are not true at all (I just think that they want you to buy their central air conditioners).

If you are comparing just the air conditioner itself, I may agree that some central air conditioners are cheaper than mini splits. However, if we see the air conditioning system as a whole, central air conditioners are way more expensive with all the ducts, insulations and grilles.

Meanwhile, for mini split air conditioners, you just need to drill a few holes and pull some copper tubes and you are done. In the United States, mini split air conditioners even come with all the pipes and accessories which I’ve never seen here in Malaysia or China (I’ve been there for training btw).

Operating Cost

The mini split air conditioner by far is the most efficient form of the air conditioner. Energy Star had stated in their website that ductless mini splits consume 30% less energy than other rooms air conditioners such as window and portable type.

Furthermore, almost all mini splits are capable of providing both heating and cooling which we called heat pumps. While a gas furnace only has about 30% energy efficiency plus emitting carbons, a mini split heat pump is about 3 times more efficient than an electric space heater.

Find out Are Mini Splits Supposed to Run All the Time?

The mini split heat pumps basically reverse the air conditioning process to switch from cooling to heating. So, they adopted the refrigeration cycle to extract heat from the ambient air and transfer it into the house. Such a heating method yields a COP of 3.0 which means that for every kilowatt it consumes, 3kW of heating is produced.

Speaking of efficiency and save energy, you should check out my post Here is Why You Should Use a Heat Pump for Heating where I unpack how much money you can save by using a heat pump versus the old gas system for heating.

I hope now that you understand why mini split air conditioners are better and we can continue on with the guide to get you the right one for your house.

Capacity of Ductless Mini Split Air Conditioners

First of all, you need to know that in terms of heating, mini split air conditioners have limitations. Typically, most mini split heat pumps hit their operation limit when the ambient air temperature reaches 5°F. Beyond that, some may stop working entirely. You can read more about it in my post: Do Mini Splits Work in Cold Weather?

In terms of cooling, not a problem.

Next, the most important thing is to use the right size air conditioner. For the mini split, you need to calculate the floor area for each room. I know some central air conditioning estimate the capacity by using the floor area of the entire house.

It strikes me again that a central air conditioner cools and heats the entire house. Imagine you are sleeping in the bedroom and the air conditioner is cooling the living room and the kitchen. It’s crazy.

Instead, mini split air conditioners are installed individually in the room that you wish to have cooling and heating. When you use the room, you turn on the AC. If you don’t, you switch it off.

I have a few posts that can help you to get a good idea of how to calculate the capacity needed. They are tailored for insulated houses:

After you’ve calculated the capacity needed, you’ll need to decide the type of indoor unit that you want, or should I say suitable for your house. Though I’ve covered the type of indoor unit in some of my posts linked above, I quickly walk through again.

Types of Mini Splits Indoor Unit

There are basically three types of indoor units that are suitable for a normal house; a) wall-mounted, b) ceiling cassette, and c) ceiling concealed.

The wall-mounted type is by far the most common one for mini splits. They are installed up high on the wall. They are fit whether your room has a ceiling or not. They are the simplest type of indoor unit.

Then, we have the ceiling cassette type which has to be suspended from the slab. They are usually good for square-shaped rooms due to their 4-way air distribution. However, they are more expensive and slightly harder to install. Without the ceiling, they look naked.

Lastly, the ceiling concealed type or some people prefer to call them ducted unit. As the name suggests, they usually connect to ducts. However, they also can work without ducts. They need to be installed above the ceiling or else, no point using this type of indoor unit.

Each type of indoor unit has its own specific advantages. Nonetheless, you’ll be using the wall-mounted type most of the time.

Wall-mounted type essentially has zero downsides for a typical house. Other types of indoor units are mostly used in commercial buildings where there is all kinds of room shape and more importantly, they need big capacity air conditioner which wall-mounted type can’t deliver.

However, the capacity available for the wall-mounted type is more than sufficient for a typical house and it is the best type of indoor unit available now.

Placement for the Mini Split Air Conditioner

Nevertheless, you need to be aware of some of the things during installation. The indoor unit placement is particularly important to ensure you get the most out of it.

For that, I also have a post to point out exactly Where to Put a Mini Split? Don’t worry, I have tons of photos to show you the dimension and also some of the bad examples for you to get a really good idea of where to place them.

Almost always, finding a place for mini split air conditioners is not a problem at all.

Mini Splits vs Central Air Conditioners

Many people when they move into a new house, the first thing they think about the HVAC system is to refurbish the old central air conditioner and the ductwork.

Maintenance

Personally, I think it is too much hassle to repair ducts that have been leaking, insulation tearing off and disjointing. Space limitation often is the number one problem causing ineffective refurbishment which leads to you satisfy with the result.

Alternatively, you can use 5-7 units of ductless mini split air conditioners. Many people had testified that their mini splits indeed save them a lot of money on the electricity bill. On the maintenance, they are also happy with the cost and the ease of doing the cleaning work by themselves.

The working principle of the mini split air conditioner is very simple. There is no need to calculate ducts size, insulations thickness, flexible ducts size, select the correct grilles and filters. Less thing involved means less chance of getting a problem.

If you are interested to know more about the working principle behind split air conditioners, check out my post on What is Split Air Conditioner? Differences & Advantages and perhaps, What is Multi Split Air Conditioner? (Capacity Sharing).

Some people are not willing to service their central air conditioner not because they are lazy or what. Many times, it is because the procedure is complicated and exhausting. Many of them don’t really want to crawl into the attic.

You’ve got to worry about the filter, dust collecting inside the duct, the return vent filters and etc. There are just too many places that dust can be stuck on.

On the flip side, you can just use a ladder to reach the mini split indoor unit. As for the outdoor unit, some are placed on the floor and you just walk to it, use a water hose to clean the dust off. Piece of cake.

Quality

However, I must admit that there are some cheap mini splits that could break easily. But, they are hard to find now. You see, the air conditioning industry is very matured. Anyone can call up an OEM supplier in China, have their logo stamped and start importing and selling mini split air conditioners.

There are tons and tons of split air conditioner suppliers in the world. No matter they are from China or anywhere in the world, the standard of quality is high.

As a general rule, you should NOT buy any mini splits that are relatively cheaper. A lot of material in a mini split air conditioner is copper-based. We all know copper is not cheap. That’s why air conditioners are more or less the same price.

If you try to pick the cheapest one, chances are you will be getting a low quality product that could break in a month or two.

I’ve been using split air conditioners for many years. In my old house, that split AC in my bedroom was nearly 10 years old before I move to my new house. It is still functioning the day we sold the house.

Some of the popular brands in the United States are Pioneer, MrCool, Senville and Cooper & Hunter. Meanwhile, overseas brands such as Daikin, Panasonic, Mitsubishi and Fujitsu are excellent choices.

Again, I’ve some posts on some of the best mini split air conditioners in case you are interested to know. I’ll put the link in the following:

Lifespan

Typically, a mini split air conditioner lasts about 10-15 years. Older split air conditioners last up to 30 years but I don’t think they are around now (product too good, no new sales).

Nowadays, mini splits are equipped with more and more electronic boards. Though they are reliable just like a computer, electronic things fail over time and it is completely normal.

Yes, central air conditioners last longer. It is because they are using old dinosaur technology that doesn’t have any electronic control board. Sure they last longer. People nowadays are using centralized digital thermostat controllers while many central air conditioners are still using analog thermostats.

From what I’ve seen, central air conditioning systems are used more in commercial buildings such as large offices (open space), hotels lobby and hospitals. They need a large capacity which only custom-made air handling units are able to deliver.

Furthermore, the higher the capacity of the air conditioning system, the more efficient it gets. So, until one point, the return on investment for having a few central air conditioners make more sense than having tons of mini splits.

Reliability

Let’s talk about problems. Mini split air conditioners more or less are giving common problems such as refrigerant leaks, drain water overflow (yes, mini splits do need a drain), PCB failure and etc.

However, these problems are minor compared to the problems giving out by central air conditioners such as ducts condensation, insufficient airflow, freezing, rusting and many more.

As long as there are more components involved, the problem is greater. This applies to almost everything when it comes to engineering products.

Mini Splits vs Window and Portable Air Conditioners

How do mini splits compare to the window and portable air conditioners? Both the window and portable air conditioner are steered towards specific applications and they can’t really compare side by side with the mini split.

Window air conditioners hands down are the cheapest air conditioning solution. They are compact and flexible as well as you can install them by yourself much easier than mini splits.

Small rooms, tiny houses and mobile homes can use window air conditioners with no problem. Keep in mind that they are not as efficient as mini splits but they are affordable and I think it is good that we have window ACs.

Portable air conditioners are great for moving around, camping and etc. I’ve always wondered why people would want to use a portable air conditioner and fix the exhaust hose in one place. Wouldn’t that defy the purpose of the portable air conditioner?

Here, we use a portable air conditioner for temporary events where we pull it outside the house to cool while the exhaust hose is left freely discharging hot air a few meters away from the people.

Both window and portable air conditioners are not efficient and loud. I sincerely think that they are not suitable for the bedroom at all with such their noise operation. By the way, mini splits operations are barely audible.

Conclusion

There you have it. Everything you need to know about the ductless mini split air conditioners. If you are not used to mini splits and thinking of getting some, I strongly suggest that you read my post on Importance of Using the Correct Mini-Split System. It’ll point out critical things that you must pay extra attention to.

To some people, uncertainty is scary and thus, they are worried about using mini splits. However, mini split air conditioners accounted for 77% of the world’s air conditioning system used as of 2016. Furthermore, many peopl are getting into mini splits nowadays.

The best thing about ductless mini split air conditioners is simplicity. A central air conditioner by itself may have a higher energy rating but we need to see the overall efficiency which will directly reflect on your monthly electricity bill. In fact, ductless mini splits consume 30% less energy than other rooms air conditioners.

The most important thing is to use the right size air conditioner. After that, you’ll need to use the type of indoor unit that is suitable for your house. The wall-mounted type is by far the most common one for mini splits.

The indoor unit placement is particularly important to ensure you get the most out of it. However, finding a place for mini split air conditioners is not a problem at all.

Many people had testified that their mini splits indeed save them a lot of money on the electricity bill. On the maintenance, they are also happy with the cost and the ease of doing the cleaning work by themselves.

As a general rule, you should NOT buy any mini splits that are relatively cheaper. Typically, a mini split air conditioner lasts about 10-15 years. The common problem of mini split air conditioners are refrigerant leaks, drain water overflow and PCB failure.

Both window and portable air conditioners are not efficient and loud. They are not suitable for the bedroom at all with such noise operation. Meanwhile, mini splits operations are barely audible.

Mini split air conditioners are a great air conditioning solution. You will not regret it.

Yu Chang Zhen

Yu was working in the air conditioning industry for the past 7 years, covering from design to installation and maintenance. Yu wish to share all the things he learned with the people around the world.

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