OLMO OW-P12HS230WF Review: 12,000 BTU 230V Wall AC and Heater
A smart heat and cool wall unit with 12,000/11,700 BTU/h cooling and 10,600/8,600 BTU/h heating on a 208/230V circuit, with app, voice, remote and panel control.
By Daniel Brooks
Updated October 22, 2026
The OLMO OW-P12HS230WF is a 12,000 BTU through-the-wall air conditioner with a real heating section, not just a token warm setting. It is rated at 12,000/11,700 BTU/h of cooling and 10,600/8,600 BTU/h of heating at 230 and 208 volts, uses R-32 refrigerant, and has a built-in smart kit for phone and voice control. It has a 4.2 out of 5 average from 13 ratings, one of the better scores among the larger units in our through-the-wall air conditioners with heat category.
Our Verdict
This OLMO is a strong choice for a living room, a large bedroom, a small apartment or a hotel style room that already has a 208/230 volt outlet beside the sleeve. The 10,600 BTU/h heater is close to the cooling output, so it can carry a room through cool spring and fall days far better than the small heaters on standard outlet models. You can run it from the push button panel with its LED display, the included remote, a phone app or a voice assistant.
The trade-offs are practical rather than serious. The wall sleeve is sold separately, OLMO does not publish a room size for this model, and the listed 58 dB is a little louder than the quietest heat units we cover. Electric heat is also more expensive to run for long hours than a central furnace, so treat it as a strong supplemental source.
OLMO 12,000 BTU 230V Through-the-Wall AC & Heater
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Key Specifications
| Feature | Specification |
|---|---|
| Brand | OLMO |
| Model | OW-P12HS230WF |
| Type | Smart through-the-wall air conditioner with heat |
| Cooling Capacity | 12,000/11,700 BTU/h (230V/208V) |
| Heating Capacity | 10,600/8,600 BTU/h (230V/208V) |
| Power | 208/230V, 1 phase, 60Hz |
| Refrigerant | R-32 |
| Noise Level | 58 dB (listed) |
| Controls | Push button panel with LED display, remote, smartphone app, voice |
| Modes | Cooling, heating, sleep, timer, auto restart |
| Dimensions | 24.21 x 14.53 x 20.28 inches (W x H x D) |
| Weight | 85.8 pounds |
| Wall Sleeve | Sold separately |
| Warranty | 1 year limited |
Cooling Capacity and Room Size
OLMO rates the cooling at 12,000 BTU/h on a 230 volt supply and 11,700 BTU/h on 208 volts, which is the normal small drop you see on dual voltage wall units. The listing does not state a room size, so the ENERGY STAR chart below is the best guide. At 12,000 BTU, this unit lines up with rooms of roughly 450 to 550 square feet, such as an open living room, a studio apartment or a large primary bedroom.
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.
If your room is very sunny, or the unit will also cool a kitchen area, lean toward the upper end of that range or consider the 14,000 BTU OLMO. For a shaded bedroom of around 400 square feet, this unit has headroom to spare.
Heating Performance
Heat output is where this model separates itself from many wall units. OLMO lists 10,600 BTU/h of heat at 230 volts and 8,600 BTU/h at 208 volts. That is far more than the small heaters found on standard outlet models, and it is enough to warm a medium room on a cool morning without waiting long.
Because the heater is electric, the running cost scales with how many hours you use it. In mild climates, it can serve as the main heat for a room on most cool days. In colder regions, it works best as supplemental heat for a room that the central system does not reach well, such as a converted garage, an addition or a corner office.
Power and Electrical Requirements
The unit is designed for 208/230V, single phase, 60Hz power, and OLMO asks buyers to confirm that they have the correct receptacle before ordering. That outlet is common in apartment buildings and older homes with existing wall units, but it is different from a standard household outlet. If your sleeve has only a regular household outlet, the 8,000 BTU OLMO is the matching standard outlet option.
Installation and Sleeve Fit
The chassis measures 24.21 inches wide, 14.53 inches tall and 20.28 inches deep, and the listing gives a minimum opening width of 24 inches. OLMO sells its own TTW sleeve separately, and there is also a version of this model that ships with the sleeve. At 85.8 pounds, installation is a job for two people, and the sleeve should be level from side to side with a slight tilt toward the outside so condensate can drain.
The listing also mentions a self evaporating system, which helps the unit manage condensate during normal cooling.
Smart Controls and Everyday Use
The built-in smart kit is a real convenience. The listing names app, push button, remote and voice control, so you can switch from cooling to heating, change the set point or start the timer without walking to the wall. That is handy for a room you want warm or cool before you arrive. The remote adds sleep mode and a timer, and auto restart brings the unit back to its previous settings after a power outage.
Noise and Efficiency
OLMO lists 58 dB for this model. That is acceptable for a living room or office, and many people sleep fine with it, but light sleepers may prefer a unit with a lower listed figure. R-32 refrigerant is a newer, lower global warming potential refrigerant that is now common in current wall units.
Who It Suits Best
The OW-P12HS230WF suits medium to large rooms with a 208/230 volt outlet, in homes that want strong heat for cool seasons and app control. It is a sensible upgrade for an aging heat and cool wall unit in an apartment. It is less suited to homes with only standard outlets, very small rooms, or anyone who wants the quietest possible bedroom unit.
Pros and Cons
| Pros | Cons |
|---|---|
| Heater rated at 10,600 BTU/h on 230V | Needs a 208/230V outlet |
| App, voice, remote and panel control | Sleeve sold separately |
| 4.2 out of 5 average rating | No room size listed |
| R-32 refrigerant | 58 dB listed sound level |
| Sleep mode, timer and auto restart | Heavy at 85.8 pounds |
Who Should Buy It
| Who Should Buy It? | Who Should Look Elsewhere? |
|---|---|
| Apartments with a 230V sleeve outlet | Homes with only standard outlets |
| Rooms that need real heat on cool days | Small bedrooms |
| Smart home users | Light sleepers wanting a quieter unit |
| Replacements for older heat and cool units | Buyers wanting the sleeve in the box |
For more choices, see our picks for the best 12,000 BTU through-the-wall air conditioners with heat and the best 230V through-the-wall air conditioners with heat.
Final Verdict
The OLMO OW-P12HS230WF combines a solid 12,000 BTU cooling section with one of the strongest heaters in its size, plus full smart control. If you have a 208/230 volt outlet and want one appliance for summer cooling and genuine shoulder-season heat, it is one of the best values in the category. You can check the current price and details for the OLMO 12,000 BTU 230V Through-the-Wall AC and Heater.
Frequently Asked Questions
How much heat does the OLMO 12,000 BTU unit produce?
OLMO lists 10,600 BTU/h of heat at 230 volts and 8,600 BTU/h at 208 volts.
Does it work with Alexa or Google Assistant?
The listing names voice control through the built-in smart kit, along with app, remote and panel control.
What outlet does it need?
It is designed for 208/230V, single phase, 60Hz power. Confirm your receptacle before ordering.
Is the wall sleeve included?
No. The sleeve is sold separately in this listing.
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.