Soleus Air 12,000 BTU Saddle AC Review: Inverter, Heat, Wi-Fi
A saddle-mount inverter window air conditioner with 12,000 BTU cooling, 10,000 BTU heat and Wi-Fi app control. Built for thick walls up to 12.5 inches and year-round use.
By Daniel Brooks
Updated October 12, 2026
The Soleus Air 12,000 BTU Saddle AC is an inverter window air conditioner that straddles the wall, with the quiet section inside and the compressor outside. It adds 10,000 BTU of heat, so it can run in every season, and it is built for extra thick walls and sills up to 12.5 inches. It is one of the few saddle window air conditioners with a heat mode, sold as model WS5-12HW-301.
It has 3.1 stars from 96 ratings, a lower score than most units in this category, and we evaluated it based on the manufacturer’s specifications.
Our Verdict
This Soleus Air is the pick for a larger room where you want one saddle unit to handle both cooling and heating. Its inverter compressor runs at variable speeds for steadier temperatures, the Wi-Fi app lets you cool or heat the room from anywhere, and the saddle design sits low over the wall so it cannot fall out of the window.
The trade-offs are the modest rating, a noise figure that the listing reports two different ways, and a high weight of 64.6 pounds. If you have a thick wall and need heat as well as cooling, it fills a gap few saddle units cover.
Soleus Air 12,000 BTU Window Air Conditioner
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Key Specifications
| Feature | Specification |
|---|---|
| Brand | Soleus Air |
| Model | WS5-12HW-301 |
| Type | Saddle-mount inverter window air conditioner |
| Cooling Capacity | 12,000 BTU |
| Heating Capacity | 10,000 BTU |
| Efficiency | 13 (listed as SEER) |
| Power | 115 volts, 1220 watts |
| Wall Fit | Walls and sills up to 12.5″ thick |
| Noise Level | 38 dB in the feature text, 48 dB in the specifications |
| Dimensions | 31.8″D x 18.7″W x 15.2″H |
| Weight | 64.6 pounds |
| Filter | Washable filter (activated carbon type in specs) |
| Controls | Soleus Air Wi-Fi app |
| Refrigerant | R-32 |
| Warranty | Limited |
Cooling Capacity and Room Size
Soleus Air rates cooling at 12,000 BTU, driven by an inverter compressor that varies its speed instead of cycling fully on and off. That usually means steadier temperatures and lower energy use once the room reaches the set point. The listing does not give a recommended room size, so use the general chart below.
ENERGY STAR publishes this general guide for sizing a room air conditioner by floor area:
| Room Size (sq ft) | Cooling Capacity (BTU/hr) |
|---|---|
| 100 to 150 | 5,000 |
| 150 to 250 | 6,000 |
| 250 to 300 | 7,000 |
| 300 to 350 | 8,000 |
| 350 to 400 | 9,000 |
| 400 to 450 | 10,000 |
| 450 to 550 | 12,000 |
| 550 to 700 | 14,000 |
| 700 to 1,000 | 18,000 |
Adjust for your room: reduce capacity by 10 percent for a heavily shaded room, increase it by 10 percent for a very sunny room, add 600 BTU for each regular occupant beyond two, and add 4,000 BTU if the unit cools a kitchen. Source: ENERGY STAR.
At 12,000 BTU, the unit lines up with the 12,000 BTU row, which ENERGY STAR matches to rooms of about 450 to 550 square feet. That makes it a fit for a large bedroom, a living room or a studio apartment, which is more than most saddle units are built for.
Heating
The unit includes 10,000 BTU of heat, so Soleus Air calls it a 4-season model. For a room that gets cold in winter but has no other heat source, that removes the need for a separate space heater. Use the heat function for a single room rather than as a whole-home system.
Installation and Fit
The saddle design straddles the wall, so the unit sits low and over the sill rather than balanced on it. Soleus Air says this makes it virtually impossible to fall out and removes any need to drill holes in the window for support. It is sized for extra thick walls and sills up to 12.5 inches.
Because the bulk of the unit sits below the window, the window stays open for a breeze and the view stays clear. An installation kit is included. At 64.6 pounds and 31.8 inches deep, this is a two-person job, and the window opening figures in the listing are inconsistent, so measure your window and wall and read the manual before you buy.
It runs on a standard 115 volt outlet, so no special wiring is needed.
Noise, Energy Use and Efficiency
The feature text says the saddle design moves the noise outside, putting the indoor sound level near a library at 38 dB. The specifications list 48 dB. Expect the lower figure at low fan speed and in Sleep Mode, and something closer to the higher figure when the unit is working hard.
Power draw is listed at 1220 watts, and the specifications list an efficiency figure of 13, labeled as SEER. The inverter compressor is the main efficiency feature, and Sleep Mode moderates the set temperature at night to save energy.
Controls and Smart Features
The Soleus Air Wi-Fi app lets you cool or heat the room from anywhere using a smart device. You can change the temperature, switch between heat and cooling, and turn the unit on before you get home.
Sleep Mode automatically moderates the set temperature through the night, so the room does not overcool while you sleep. The listing does not mention voice assistant support, so plan on the app as the main control.
Maintenance and Drainage
The washable filter captures dust from the air and helps the unit run efficiently. The specifications list it as an activated carbon type. Rinse it regularly during the cooling and heating seasons.
The listing does not describe a drain pump or a self-evaporating system, so follow the manual for drainage and for the slight outward tilt most window units need.
Pros and Cons
| Pros | Cons |
|---|---|
| 12,000 BTU cooling plus 10,000 BTU heat | 3.1 stars from 96 ratings |
| Inverter compressor for steadier temperatures | Noise listed as both 38 dB and 48 dB |
| Saddle mount fits walls up to 12.5″ thick | Heavy at 64.6 pounds |
| Window stays usable with the view clear | No voice assistant support listed |
| Wi-Fi app control on a 115 volt outlet | No room size rating in the listing |
Who Should Buy It
| Who Should Buy It? | Who Should Look Elsewhere? |
|---|---|
| Rooms of about 450 to 550 sq ft | Small bedrooms that need only 6,000 BTU |
| Thick walls or deep sills up to 12.5″ | Buyers who want Alexa or Google control |
| Rooms that need both cooling and heat | Anyone who cannot lift a 64.6 pound unit |
| Homes where the window must stay usable | Buyers who put ratings first |
Final Verdict
The Soleus Air 12,000 BTU Saddle AC combines a saddle mount, an inverter compressor and 10,000 BTU of heat in one unit, which few window air conditioners offer. It suits a larger room with a thick wall where you want year-round comfort and a clear, usable window. The compromise is a lower rating than its rivals, conflicting noise figures and a heavy install. You can check the current price and details for the Soleus Air 12,000 BTU Window Air Conditioner with Heater.
Frequently Asked Questions
What size room does the Soleus Air 12,000 BTU cool?
The listing does not give a room size. On ENERGY STAR’s chart, 12,000 BTU covers rooms of about 450 to 550 square feet.
Does it heat as well as cool?
Yes. It provides 12,000 BTU of cooling and 10,000 BTU of heat, so it can run year-round.
How thick a wall does it fit?
It is sized for extra thick walls and sills up to 12.5 inches. The saddle design sits over the wall, so no drilling is needed for support.
How quiet is it?
The feature text compares it to a library at 38 dB, while the specifications list 48 dB. Expect the lower figure at low fan speed or in Sleep Mode.
About the author
Daniel Brooks is a home cooling editor at WikiCooling, covering window, portable, through-the-wall and mini-split air conditioners, fans, and dehumidifiers. He researches cooling capacity, energy efficiency, noise levels, installation requirements, and buyer feedback to help homeowners choose the right unit for their room size, climate, and budget.