What is the Smallest Mini Split Available?
If you have a small room and you’re thinking about the possibility of using a mini split air conditioner to cool the room, I have 4 options for you and a few ideas on how to go around it.
Currently, the smallest mini split available in terms of the cooling capacity is 6000 BTU. But, because mini splits have variable-speed compressor, the lowest BTU a mini split can ramp down to is around 2000 BTU which, the corresponding minimum room size is 100 sqft.
However, that doesn’t mean you should use a 6000 BTU mini split in a 100 sqft room. There are a few things that we need to check and consider before making a conclusion.
4 Smallest Mini Splits for Small Rooms
Here are the 4 smallest mini splits currently available on the market:
1. Cooper & Hunter MIA
- Cooling Capacity: 6,000 BTU
- Power: 115V
- Efficiency: 21.5 SEER2
Cooper & Hunter offers a 6000 BTU mini split in their MIA series. It is a single-zone unit with entry-level price. It is powered by 115V which is simpler to install. However, the efficiency is only 21.5 SEER2 which is not considered high but decent.
Cooper & Hunter is a brand that I’ve seen over and over again. They have quite a mini split product lineup, from single zone to multi zone, covering different price range and features.
So, I do recommend this Cooper & Hunter MIA 600 BTU 115V for your small room.
2. Durastar DR1H09W06
- Cooling Capacity: 6,000 BTU
- Power: 230V
- Efficiency: 23.5 SEER2
Durastar has a 6000 BTU mini split. It is a relatively higher efficiency model compared to the previous one. However, it needs 230V which could make your installation more costly.
To be honest, I don’t really come across Durastar brand as often as other brands listed here when it comes to mini split. So, I’ll not make any recommendation now.
3. Mitsubishi MSZ-FS06NA
- Cooling Capacity: 6,000 BTU
- Power: 230V
- Efficiency: 32.2 SEER
Mitsubishi also has the one-and-only 6000 BTU mini split which is from their MSZ-FS series. It is highly efficient but very costly. Similarly, it needs 230V.
Mitsubishi is widely regarded as the most reliable brand when it comes to mini split and I do agree, especially after my recent conversation with a senior technician. However, reliability often comes at a higher price.
So, if you have the budget, I recommend getting the Mitsubishi MSZ-FS06NA for your small room.
4. Cooper & Hunter Olivia
- Cooling Capacity: 6,000 BTU
- Power: 115V or 230V
- Efficiency: 23.5 SEER
Cooper & Hunter has another 6000 BTU mini split from their Olivia series which has higher energy efficiency. However, the downside is slightly higher price but you can choose between 115V or 230V.
Again, Cooper & Hunter is quite a popular brand and I think you’ll do fine with their mini split.
So, if you’re not tight on budget, then you can consider a higher efficiency unit to save energy.
What is the Minimum Room Size for a Mini Split?
How much BTU you need is corresponding to the square footage of your room. Since the smallest mini split is 6000 BTU, the minimum room size is between 100-300 sqft.
The 100-300 sqft room size is generally derived based on 20 BTU per sqft which is a widely-used rule of thumb for sizing mini splits.
- 6000 BTU ÷ 20 = 300 sqft
As for the smallest room size of 100 sqft, it is based on the ramp-down capability of the mini split.
Typically, a 6000 BTU mini split can ramp down to a minimum of 2000 BTU. That’s how the 100 sqft room size comes about.
- 2000 BTU ÷ 20 = 100 sqft
When it comes to mini splits, the 6000 BTU is their “rated cooling capacity”. If you want to see how far their capacity can go up and down, you can refer their specification sheet. For example:
This Cooper & Hunter MIA 6000 BTU mini split can ramp down to a minimum of 2650 BTU which, the corresponding minimum room size is instead 132.5 sqft, based on 20 BTU per sqft calculation.
If we compare all mini splits on the market now (which I did), the lowest BTU can be achieve (on paper) is 1030 BTU by the LG ArtCool Premier (which surprisingly is a 9000 BTU mini split).
So, if based on 1030 BTU, the minimum room size is now 51.5 sqft. Pretty wild right?
On top of that, the 20 BTU per sqft number that we use is a general assumption of how much heat is present in a room. If your room has a west-facing window, the heat gain is greater and thus, the BTU per sqft number needs to be higher.
There are a lot to consider if we want a definitive answer. So, in short, I would say the minimum room size for a mini split is 100 sqft.
What Happen If You Oversize a Mini Split?
When a mini split is oversized (too big) for a room, apart from having a room that’s too cold and high energy bill, here’s what else typically happen:
- Room temperature drop too fast, leaving no time for dehumidification (high room humidity level).
- The other side of the wall or window may have condensation due to low temperature.
- Possibly a compressor low-pressure trip due to low heat extraction.
Mini splits have inverter technology which keeps their compressor running all the time (at low or high speed depending on the cooling needs). So, an oversized mini split doesn’t really cycle on/off frequently like traditional ACs. Instead, they just hold at the lowest compressor speed.
The key takeaway here is the humidity issue. Oversized mini splits and any other air conditioners will not be able to remove sufficient humidity because they cool the air too fast.
So, if your small room needs humidity control (eg.: is a bedroom), then you should not risk it.
BUT, if your small room is a server room or a no-people-is-staying-there room, then using an oversized mini split is fine because there is no moisture to control. Humans are the one that produces the moisture.
In commercial offices, it is common to use a mini split that’s way too big for a computer server room because we don’t want to rely on the central AC system as it can fail and bring down the server. Two mini splits (1 duty 1 standby) is the common design practice.
Can You Use Mini Split in a Small Room?
So, if you have a room that’s smaller than 100 sqft. Can you still use a mini split without getting into any of the oversizing trouble?
The answer is maybe…it depends.
The easiest thing to check if you can use a 6000 BTU mini split in a <100 sqft room is by judging how much heat is present in the room. For example:
- Is there any window?
- Is the wall well insulated or not? It is an exterior wall (more heat)?
- Do you have heat emitting equipment in there?
- Are the room going to be occupied by more than one person?
These are the things that you can look for when judging if there is enough heat for a 6000 BTU mini split.
Generally, if the room has an exterior wall and a window, then I would say a 6000 BTU mini split is fine. Also, if the room is an interior room but you have a bunch of servers (IT equipment) in it, then I would also say it is fine to use a 6000 BTU mini split even though the room size is <100 sqft.
Alternatively, you can use a ducted mini split and divert just a little airflow to cool the small room.
Using a ductless wall mount unit, there is a little chance that you can share a unit between two rooms unless you install in between the wall? Though I’ve seen people done that.
If you have anything to add (or ask) about this topic, leave a comment down below!
