Multi Split or Single Split? Consider this ONE thing.


A new 3 bedroom apartment sometimes come with a multi-split air conditioner. Multiple indoor units connected to a single outdoor unit. Is it better?

You may have already seen many pros and cons between the multi-split and single split air conditioner. But, there is one important thing to consider before you get carried away by all the benefits because you may end up not able to realize them and it is not the multi-split faults.

The ONE thing to consider before buying a multi-split air conditioner is your usage behaviour.

At a glance, multi-split and single split might look exactly the same. However, after a while of using a multi-split air conditioner, you'll notice that the benefits that you are supposed to get from the multi-split air conditioner do not apply to you.

We can all agree that changing the system after you've done the installation is almost always not worth the money and trouble. So, if you are considering a multi-split air conditioner, you must understand how your usage behaviour can affect the benefits that the technology promised.

Usage Behaviour

In a multi-split air conditioning system, the capacity of the outdoor unit is always lower than the sum of all its associated indoor units because of the diversity factor. When sizing for a multi-split air conditioner, we usually calculate the total capacity required for the indoor units and then, apply a diversity factor to select the size of the outdoor unit.

The above is a typical multi-split air conditioning design. You'll notice that the total capacity for the indoor units is 4.5HP while the outdoor unit is merely 3.0HP. So, how does the system achieve the desired cooling? Will it be called “under-capacity”? Well, this is the purpose of the multi-split air conditioning system.

When designing a multi-split system, we must take into consideration usage behaviour. We assumed that at any given moment, all three rooms (children, bedroom & living room) will not be using the air conditioner simultaneously. We made an assumption that if we are using the air conditioner in the living room, we are not using the air conditioner in the bedroom or vice versa.

This assumption made must be aligned with the actual usage behaviour. If we happen to use all three rooms at the same time, the outdoor unit will not have sufficient capacity to keep up with the desired cooling and therefore, the system fails.

The Benefit of Multi-Split System

Ask yourself first if you and your family are practicing suitable usage behaviour to use a multi-split air conditioning system. If yes, here is a quick overview of the benefits this technology can bring to you:

  1. Lower Capital Cost
  2. Lower Service Cost (Potentially)
  3. Space Saving

The multi-split air conditioner was developed to replace complex ductwork for medium size spaces like apartments and offices due to its simplicity and cost-effective characteristic. Let's dive into each benefit.

How to make a split-screen for two ...
How to make a split-screen for two video clips.

Lower Capital Cost

Multi-split Inverter System (1+3)

Retail Price
(as of Jan 21)
Outdoor ModelIndoor ModelMax. Indoor
Cap. (btu/hr)
(run 3 units)
Max. Indoor
Cap. (btu/hr)
(run 2 units)
Max. Indoor
Cap. (btu/hr)
(run 1 unit)
RM 4,100MKC50RVMCTKC25RVM6,755 (run)9,041 (run)11,703 (run)
CTKC25RVM6,755 (run)9,041 (run)0 btu/hr (off)
CTKC25RVM6,755 (run)0 btu/hr (off)0 btu/hr (off)
Data Captured from DAIKIN Malaysia.

Single-split Inverter System (1+1)

Retail Price (as of Jan 2021)Indoor ModelOutdoor ModelMax. Cap. (btu/hr)
RM 1,460 x 3 units = RM 4,380FTKG28QV1L/MRKG28FV1D10,200
Data Captured from DAIKIN Malaysia.

Based on the above data, it is cheaper at the product price when you choose the multi-split over the single-split for 3 indoors each at 1 HP air conditioner.

However, we can see from the multi-split table that if 3 indoors are running simultaneously, you will only get half of the capacity or about 0.5 HP. But, if you only need 2 indoors to run at the same time, then the multi-split is perfect for you (each indoor delivers about 1 HP).

Lower Service Cost (Potentially)

In Malaysia, most of the air conditioner service price (chemical wash) is about RM 120 to RM 150 depends on location and other factors. The calculate typically is based on the quantity of the single-split indoor unit inclusive of the associated outdoor unit. Meaning most of the aircond technicians will charge you about RM 400 to service THREE single-split indoor and outdoor unit.

With a multi-split system, you can negotiate for a lower price like RM 350 because you have only one outdoor unit. Bear in mind that you should not hope for a quantity-based price deduction because the outdoor unit of the multi-split is relatively bigger and thus, takes a longer time to service. Nevertheless, the final price is subjected to your negotiation with the servicer.

If you happen to have gas leakage, the price of the gas refilling should be the same for multi-split and single-split system because the multi-split system has the same refrigerant pipe length and size as the single split system.

Space Saving

Because multi-split has only one outdoor unit, although it is bigger, it is still much more compact than 3 pieces of the single-split outdoor unit.

Image Captured from DAIKIN Malaysia.

If you have an apartment unit, it is a smart choice to use multi-split because every square meter is money. Three outdoor units basically occupied all of your balcony space. Instead, with one multi-split outdoor unit, it usually left enough space for a washing machine or coffee table.

How about the Disadvantages of the Multi-Split System?

The product manufacturers will almost never tell publicly about the disadvantages of the multi-split system. Of course, it makes no sense to do so from a business perspective. However, you should know the reason not to consider the multi-split system here before you visit the store and get persuaded by some unethical salesman.

A quick list of the disadvantages of the multi-split air conditioner system as below:

  1. Higher impact if broke down
  2. Higher cost to repair

Sometimes, we can't blame the salesman for not telling us the disadvantages beforehand because they themselves might not even aware of it. These disadvantages may not be obvious but once you encounter them, you'll feel the pain. So, might as well you consider it before deciding to go for the multi-split system.

Higher Impact If Broke Down

The broken-down precisely refers to the outdoor unit. Because the multi-split system only has one outdoor unit that serves multiple indoor units, the breakdown of the outdoor unit means your entire house will suffer.

All the indoor units are connected back to the same outdoor units in a multi-split air conditioning system. The outdoor unit usually has one or two compressors (depends on the capacity) and one IC board to control the entire system. If the IC board fails, the outdoor unit and all connected indoor units are unable to function.

If gas leaking occurs in any of the refrigerant pipelines, the entire system will fail too. In the multi-split system, all refrigerant pipes are linked together. Any pipe cracks will result in the entire refrigerant gas being leaked out.

Consequently, the entire refrigerant pipeline will need to be checked and repaired. Then, the refrigerant gas of all indoor units needs to be recharged and this often doubles, if not triples the amount of repair time when compared to the single-split system.

On the other hand, the single-split system will not have such an issue because they are not linked to each other and each of them can be repaired and serviced individually.

If you need to estimate the service time for the single-split system, you can check out my previous article here where I breakdown the servie time for each task.

Higher Cost to Repair

As mentioned above, any gas leaking will result in the depletion of all of the gas inside a multi-split system. Thus, even though it is only one pipeline leaks, you'll need to pay the gas refill price for the whole system. This often double the cost when compared to the single-split system.

Furthermore, the multi-split system is more complicated than the single-split system. Hence, the components of the multi-split system is pricer. On top of that, many aircond service shops usually don't keep stock for multi-split aircond parts because not many people are using the multi-split system. This could result in a longer breakdown down for you.

My Take on Multi-Split Air Conditioning System

Personally, I don't like the multi-split system. They are too dependent on the single outdoor unit. I don't question the product reliability of reputation manufacturers but the air conditioner is still a mechanical system with lots of moving parts and moving parts will eventually fail.

Yes, its smart way of diversify capacity to provide benefits over the single-split system is appealing especially for those who really have limited space. But, if I'm looking at 10 years down the road, the benefits still couldn't justify its disadvantages.

If you are into the multi-split system, confirm again on the usage behaviour in order to realize its benefits. Next, get a branded one like Daikin and Panasonic. Then, get it installed by a good technician to ensure you minimize any risk of breakdown. Finally, take good care of your air conditioners and service them regularly.

If space limitation is your main issue with the single-split system, try to discuss with the aircond installer to come out with creative ideas such as adding a duct to channel out hot air or stacking multiple units so that you have more flexibility on the location of the outdoor unit.


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Yu Chang Zhen

I enjoy working on air conditioners and ventilation fans because Malaysia is a very hot country.

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