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All You Need To Know About Aircon Casements

casement aircon

The first thing that comes to mind when we say aircon unit is that it is the standard wall-mounted type of aircon unit that is incredibly common in Singaporean households. It comes as no surprise that these aircon units are so popular, with the Singaporean heat and humidity. For most homeowners, aircon units have practically become a necessity and not anymore a luxury, especially in the broiling summer months.

What Are Aircon Casements?

Also called a slider, window, or vertical aircon unit, casement aircon is best for sliding windows, ones that slide from left to right. These types of aircon units work just like a traditional unit, drawing heat and humidity out of a room and dumping the heat into the air outside. 

Casement aircon is extremely underutilized in Singapore, despite being a great choice for small apartments and single rooms. Casement aircon is much more discreet than the traditional aircon units, as they’re smaller and sit in your window, rather than having a big, bulky machine up on the wall. 

It is also much easier to install than the traditional aircon units, allowing you to save a ton of money, not just on the aircon unit itself, but also on the installation fees. Not to mention, if you decide to move, you can just bring the aircon unit with you. 

Casement vs Vertical vs Slider vs Sliding Window Aircon Unit (Terminology Explained)

If you have a narrow window or a sliding window, it’s only natural that you won’t look for standard window aircon units. You really have to find an aircon unit that will fit into the casement or sliding window.

There is no uniform term for these narrow aircon units. Several terms are in use and they all mean the same type of window aircon unit. To not get confused when checking these aircon units, let’s look at the various names that are used to describe these aircon units:

Casement window aircon unit: Most commonly used phrase for an aircon unit that fits a casement window.

Vertical window aircon unit: A term used to describe window aircon units that fit vertical windows.

Sliding window aircon unit: These are aircon units that fit a sliding window; you can install a sliding window aircon unit, slide the window as close to the aircon unit as possible, and use the kit to fill in the window gaps.

Slider window aircon unit: Pretty much the same idea as sliding window aircon units; sliding windows are generally referred to as “slider windows”. Hence the term “slider window aircon units”.

Aircon unit for crank window

Thin or thinnest aircon unit: Basically, just an aircon unit with the highest ratio between height and width; thinnest aircon unit.

In short:

All these terms are used interchangeably for the same type of window aircon unit.

What are the factors to look for in slider window aircon units?

Cooling Capacity (Measured in BTU/hr)

The function of the casement window aircon unit and any other aircon unit is to deliver a cooling effect. The cooling effect is measured in British Thermal Units or BTU. Standard double-hand window aircon units produce anywhere from 6,000 BTU to 15,000 BTU or even more.

Slider window aircon units have a narrower cooling capacity. In practice, you will only find 8,000 BTU or 10,000 BTU casement window aircon units. 10,000 BTU window aircon units for crank windows or slider windows are by far the most prevalent due to a very simple reason: pretty much everybody is looking for a 10,000 BTU casement window aircon unit. It’s the golden-standard capacity and by far the most sought-after vertical aircon unit capacity.

Recommended Coverage Area (Based on BTU)

Based on the cooling effect (BTU), we can calculate how large a space that particular casement aircon unit can cool down. This is known as the recommended coverage area for the casement type of window aircon unit. However, for environmentally-friendly usage, the EPA recommends that the aircon unit cooling effect to cool down 1 sq ft should be 20.

Example: If you’re looking to cool down a 500 sq ft area, you should look for a 500 sq ft * 20 = 10,000 BTU slider window aircon unit.

Of course, that’s the absolute lower limit. In practice, producers who calculate the recommended coverage area recommend 10,000 BTU aircon units for up to 450 sq ft.

EER Rating (Energy-Efficiency, important for long-term electricity savings)

Vertical window aircon units should be energy-efficient. If they are, you will likely pay less for energy over the next 10 years. If they are not, you will likely pay more for electricity in the next 10 years. Energy efficiency is measured by the EER rating. 2

EER stands for Energy-Efficiency Ratio and is calculated by dividing the cooling effect (in BTU) by maximum energy input (wattage). The higher the EER rating, the more energy-efficient a vertical window aircon unit you have, and you’ll pay less in electricity costs.

Example: 10,000 BTU powered by 1000 W has an EER rating = 10,000 BTU / 1000 W = 10.

Pro 338 Reminder: Any casement aircon unit with an EER rating of 10 is considered energy efficient. You can find EER 8 and 9 rated sliding window aircon units as well.

Minimal Window Width And Height (Important for fitting in the window)

The whole point of aircon units that fit into casement windows is that they are narrow. It only makes sense: a narrow aircon unit to fit a narrow window. Standard window aircon units require the minimal window width to be at least 20″ or even 25″. Of course, the vertical casement slider windows tend to be 20″ or narrower. That’s why all casement window air conditioners have a width less than 15″.

Pro 338 Reminder: You also have to be careful since, despite casement window aircon units measuring less than 15″ in width, that does not account for the width of the crank window aircon unit installation kit.

That can add an additional inch to the total width of the slider window aircon unit. All producers will give you the minimum window width in the specification sheet. All top casement window aircon units have a minimum window width of 15 1/2 inches, that’s the industry-standard dimension.

The height is less problematic, these are, after all, vertical windows. To double-check if the casement aircon unit will actually fit into your casement or slider window, make sure that your window’s height falls into the specified minimum and maximum window height interval or better call for the assistance of a professional aircon servicing provider.

Noise Levels (Quiet casement window aircon units are preferred)

Noise levels are quite straightforward; everybody prefers a quiet aircon unit. The slider window can be a bit louder than conventional aircon units. To make sure the vertical unit has a super silent operation, check the noise levels. Everything below 60 dB is considered quite quiet.

Casement window aircon units will have 2-decibel specs, for noise created on the inner side (facing the room) and for noise generated on the outer side (facing the outdoors). The inner side noise levels are the ones that count; you will be in your room with the casement aircon unit on.

Advantages of casement aircon units:

– Fewer risks involve

– Need less permission


Disadvantages of casement aircon units:

– Not easy to refill

Let’s take a look at the available window / casement aircon unit in the market that still can be found in the NEA registered database goods.

Note that these are subject to availability from the suppliers, aircon contractors, and also professional aircon servicing companies:

1) Trentios

Model: SIN-TC1

Cooling Capacity: 2.3kW/7,843 BTU/hr

Power Input: 780W

Key Features:

Easy Installation and Removal

No Hacking of Walls

Washable Filter

6 Years Warranty On Compressor

Remote Control

2) EuropAce

Model: EAC 397

Cooling Capacity: 2.34kW/7,979 BTU/hr

Power Input: 807W

Key Features:

Easy Installation And Removal

No Hacking of Walls

Titanium Dioxide Filter

5 Years Warranty On Compressor

Remote Control

3) LG

Model: UWC096CBMM1

Cooling Capacity: 2.7kW/hr/9,212 BTU/hr

Power Input: 880W

Key Features:

4-Way Air Deflection

Auto Swing

Slide-out Chassis

Fresh Air Ventilation

5 Years Warranty On Compressor

Remote Control

4) FujiTECH

Model: FW-09F

Cooling Capacity: 2.78kW/9,479 BTU/hr

Power Input: 870W

Key Features:

4-Way Air Deflection

Auto Swing

Fresh Air Ventilation

5 Years Warranty On Compressor

Remote Control


It’s always a good time to talk about the common issues that aircon units have. This way, you’ll be able to spot if there are problems with your unit or not and prepare for its replacement accordingly. If you require our aircon servicing services, Whatsapp us at +65 9222 4141 for a fast and transparent quote.

338 Aircon Servicing Singapore ( provides an extensive range of Aircon Services including Aircon Servicing, Aircon Repairs, Aircon Installation of the best aircon brands, Chemical Overhaul, Gas Top-up, Aircon Leaking Water, and Aircon Not Cold Fix, and more. We have a team of professional technicians who are equipped with vast knowledge and experience in the Aircon industry. 

We have over 15 years of experience in dealing with aircon works and have completed thousands of aircon works for both residential (Landed, Condo, and HDB) and commercial. We are a highly recommended Aircon Company in Singapore, with many delighted customers and reviews over the years on Google and Facebook.

WhatsApp us at +65 9222 4141 for a transparent quotation and honest pricing for all your aircon needs or Call us at +65 9222 4141. We offer a fast and efficient service to serve any of your aircon needs!  


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