AC Without a Vent: 6 Coolers and Portable ACs by Power Draw

If you want a cooling unit with no window vent at all, the honest answer is an evaporative cooler, and the best of the group for most dry-climate rooms is the Hessaire MC18M, which the manufacturer rates at roughly 82 watts. If you want true air conditioning, every portable AC must push heat outside through an exhaust hose, so the best portable AC vent setup is a well-sealed window kit on a unit like the DREO 515S or the BLACK+DECKER 10,000 BTU. This guide compares six options on the specs that matter most to a generator and backup-power site: cooling claims, space covered and how many watts each one pulls.

The marketing around ventless air conditioners is confusing, so here is the short version. Compressor-based portable ACs remove heat from the room and have to dump it somewhere, which is why they come with a hose and a window kit. Evaporative coolers, also called swamp coolers, need no hose because they cool air by evaporating water, but they work well only in low humidity and they add moisture to the room. Some products are sold as windowless portable air conditioners but are really small evaporative coolers. We separate the two kinds clearly, then show what each demands from a generator or power station.

Portable AC Window Vent Kit, Adjustable Vertical/Horizontal Sliding Window Kit Plate for AC Unit, Seamless Portable AC Window Seal With 5.9 Inch Diameter, 59 Inch Length Exhaust Hose

Included for 'AC Without a Vent: 6 Coolers and Portable ACs by Power Draw' because the listing specifies Seamless Portable AC Window Seal With 5.9 Inch Diameter and 59 Inch Length Exhaust Hose, details this guide uses to compare options.

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Portable Air Conditioner Window Vent Kit with 59" Exhaust Hose, Adjustable Vertical/Horizontal Sliding Window Seal Plate for 5.9" AC Units, Universal AC Window Venting Kit

Included for 'AC Without a Vent: 6 Coolers and Portable ACs by Power Draw' because the listing specifies Universal AC Window Venting Kit, details this guide uses to compare options.

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Portable AC Window Vent Kit, Sliding Window AC Seal Kit 5.9" Exhaust Hose | No Coupler, Exhaust Hose Length 59", Plates 17-64", Universal Air Conditioner Window Seal Kit for Horizontal/Vertical Window

Included for 'AC Without a Vent: 6 Coolers and Portable ACs by Power Draw' because the listing specifies Sliding Window AC Seal Kit 5.9" Exhaust Hose and No Coupler, details this guide uses to compare options.

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Portable AC Window Vent Kit, Adjustable Vertical/Horizontal Sliding Window Kit Plate for AC Unit, AC Window Vent Kit, AC Window Seal With 5.9 Inch Diameter, 59 Inch Length Exhaust Hose

Included for 'AC Without a Vent: 6 Coolers and Portable ACs by Power Draw' because the listing specifies AC Window Vent Kit and AC Window Seal With 5.9 Inch Diameter, details this guide uses to compare options.

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Top Picks at a Glance

• Best Overall No-Vent Cooler: Hessaire MC18M, 1,300 CFM evaporative cooler, about 82 W
• Best Smart Portable AC With a Window Kit: DREO 515S, 12,000 BTU ASHRAE (8,000 BTU DOE) with drainage-free cooling
• Best Value Portable AC: BLACK+DECKER 10,000 BTU BPACT10WT, 5,500 BTU SACC for rooms up to 450 sq ft
• Best Mid-Size Window-Kit AC: Midea 10,000 BTU ASHRAE, 7,100 BTU SACC, app and remote control
• Best Large Water Tank Cooler: SereneLife Portable Swamp Cooler, 2,500 CFM with an 8 gallon tank
• Best Compact Indoor Cooler: EXNOS 2000CFM Evaporative Air Cooler, 5.5 L tank with 2 ice packs

Portable AC Vent and No-Vent Comparison Table

1. Hessaire MC18M: Best Overall No-Vent Cooler for Dry Climates and Low Power

• Airflow: 1,300 CFM with 2 fan speeds
• Coverage: rated for up to 500 sq ft per the listing
• Noise: 53.4 dB per the listing
• Power: about 82 W and a 4.8 gallon tank according to the manufacturer pages we checked

Best for: Garages, workshops, patios and dry-climate rooms where you want cooling with the smallest possible power draw.

Skip if: You live in a humid climate or want to cool a sealed bedroom to a set temperature.

The MC18M earns the top spot because it does one thing well and asks very little of your power supply. At about 82 watts, it draws less than a hair dryer’s power setting by an order of magnitude, so a small inverter generator or a modest portable power station can run it for hours. For backup-power readers, that low draw is the headline spec.

Evaporative cooling is limited by humidity. In dry air, water evaporates readily and the airflow feels noticeably cooler. In humid air, evaporation slows, the room gets damp and the benefit shrinks. The manufacturer’s own listing notes that the unit is most effective in dry climates and not in enclosed indoor spaces, so crack a window or door to let air flow through. If you live in a dry region, it is the most cost-efficient cooler here by a wide margin.

Ownership is simple. Fill the tank, set the fan and pump, and refill every few hours. The unit can use a garden hose with a float valve for continuous fill. Clean the pads and tank regularly to avoid odors, and drain it fully before storing it for winter.

Pros

• Very low power use
• No hose or window kit needed
• Large 500 sq ft coverage rating
• Simple controls

Cons

• Weak in humid conditions
• Needs refilling or a hose connection

2. DREO Portable Air Conditioner 515S: Best Smart AC With Drainage-Free Cooling

• Cooling: 12,000 BTU ASHRAE, 8,000 BTU DOE
• Features: drainage-free cooling, fan and dehumidifier modes
• Control: app, voice and remote
• Power: not listed for the US model; the UK 10,000 BTU version lists 1,125 W

Best for: Bedrooms and home offices where you want proper air conditioning with quiet operation and smart controls.

Skip if: You can’t run an exhaust hose to a window or door, or you have a very small generator.

The 515S is the premium compressor unit in this guide. The DOE number, 8,000 BTU, is the more realistic measure of how much cooling you actually get, while the larger 12,000 BTU ASHRAE figure is the marketing number. Always compare DOE or SACC ratings between brands if they are listed.

Drainage-free operation means the unit evaporates most of the condensate and expels it through the exhaust, so you won’t usually need to empty a tank in normal conditions. That is a real convenience for overnight use. The unit still needs a vent hose and window kit, which is what every compressor portable AC requires.

The listing does not state the US running wattage. As a planning estimate, a comparable 10,000 BTU unit sold in the UK is listed at 1,125 W, so you should plan for roughly 1,000 to 1,500 W for a 12,000 BTU model and add headroom for startup surge. Check the unit’s rating label before pairing it with a generator.

Pros

• Strong cooling for bedrooms
• Drainage-free design
• App and voice control
• Quiet-focused design

Cons

• Needs a sealed exhaust hose
• US power draw not listed

3. BLACK+DECKER 10,000 BTU Portable Air Conditioner: Best Value Compressor Portable AC

• Cooling: 10,000 BTU, 5,500 BTU SACC
• Coverage: rooms up to 450 sq ft per the listing
• Modes: 3-in-1 air conditioner, fan and dehumidifier
• Control: Follow Me remote

Best for: People who want a familiar brand and a clearly stated SACC rating at a middle price.

Skip if: You want a lower BTU rating and a lower draw for a small room.

The BPACT10WT is easy to understand because the listing gives both the 10,000 BTU headline and the 5,500 BTU SACC figure. SACC, or seasonally adjusted cooling capacity, is the standard that accounts for the heat that leaks back in around the hose and unit, so it tells you the realistic cooling. At 5,500 BTU SACC, the stated 450 sq ft coverage is likely optimistic for a hot room, and shaving that figure by a third is a sensible approach for rooms with strong sun exposure.

The Follow Me remote senses temperature at the remote’s location, which can keep the cooling focused where you sit or sleep. Like other compressor units, it requires a window kit and an exhaust hose, and the hose should be kept short and straight to avoid losing capacity.

The listing doesn’t give running watts. If you plan to use it with a generator, check the label and size the generator to the running watts plus additional starting surge.

Pros

• Clear SACC rating
• Fan and dehumidifier modes
• Follow Me remote
• Recognized brand

Cons

• Running watts not listed
• Coverage claim is generous

4. Midea 10,000 BTU ASHRAE Portable Air Conditioner: Best Mid-Size Window-Kit AC With App Control

• Cooling: 10,000 BTU ASHRAE, 7,100 BTU SACC
• Coverage: up to 300 sq ft per the listing
• Features: dehumidifier and fan modes, smart app and remote
• Power: owner discussions for a similar Midea 10,000 BTU unit cite about 900 W; confirm on the rating label

Best for: Rooms up to roughly 300 sq ft where you want app control and a higher SACC rating.

Skip if: You want a unit with the least complicated installation.

Midea lists a higher SACC figure than the BLACK+DECKER (7,100 versus 5,500), yet it claims a smaller coverage area of 300 sq ft. That suggests Midea is being more conservative with its room-size claim, which we see as a point in its favor. Real cooling depends on insulation, sun and ceiling height.

The window kit is included, and the app lets you schedule cooling. For readers using backup power, scheduling can help you control how long the unit runs on a generator, and a timer reduces fuel use.

A compressor AC draws a short surge when it starts. Generator sizing guides commonly suggest allowing for two to three times the running watts for the starting load. With a running draw near 900 W, that suggests planning for roughly 1,800 to 2,700 W of starting capacity unless the manufacturer says otherwise.

Pros

• Higher SACC rating
• Window kit included
• App and remote
• Realistic coverage claim

Cons

• Smaller stated coverage
• Installation takes some effort

5. SereneLife Portable Swamp Cooler: Best Large-Tank Evaporative Cooler for Big Spaces

• Airflow: 2,500 CFM
• Tank: 8 gallons
• Features: WiFi, humidifier and fan modes, ice packs and remote included
• Power: not listed

Best for: Large rooms, garages and shaded outdoor areas in dry climates.

Skip if: You are cooling a small, sealed bedroom or live in a humid region.

The big tank is the appeal. At 8 gallons, it can run for a long stretch before refilling, which suits a shop, porch or outdoor event more than a bedroom. The 2,500 CFM airflow is double what the Hessaire MC18M lists, so it moves a lot of air.

The listing includes ice packs, which many evaporative coolers use to chill the water. Ice packs add a modest cooling boost in dry air, but they do not turn a swamp cooler into a compressor air conditioner.

Because the listing doesn’t state wattage, we can’t say what it will draw on a generator. Evaporative coolers generally draw far less than compressor units, but check the label before you plan runtime.

Pros

• Large tank
• High airflow
• Remote and WiFi
• Ice packs included

Cons

• Power draw not listed
• Bulky for small rooms

6. EXNOS 2000CFM Portable Evaporative Air Cooler: Best Compact Indoor Cooler for Desks and Small Rooms

• Airflow: 2,000 CFM with 3 speeds
• Tank: 5.5 L, with 2 ice packs
• Function: 3-in-1 swamp cooler, fan and humidifier
• Power: not listed

Best for: Small rooms, workspaces and tents where you want modest, low-power cooling in dry air.

Skip if: You want a unit that covers an entire home or works in humid weather.

A 5.5 L tank is about 1.5 gallons, so you will refill often during long use. That’s the main trade-off for a compact body. For a desk or a small bedroom in a dry region, it is easy to carry and easy to store.

In small spaces, evaporative coolers can raise humidity quickly. Keep a window slightly open and watch for dampness on surfaces. If the room feels clammy, turn the unit off and rely on a fan.

Check the manufacturer’s page for the wattage rating. If it follows the typical pattern for small evaporative coolers, it will be a fraction of a compressor AC’s draw, but we can’t confirm the number.

Pros

• Compact and portable
• Low-power style
• Ice packs included
• Three speeds

Cons

• Small tank means frequent refills
• Power draw not listed

Also Consider

Ashihoti 4-in-1 Swamp Cooler

A 2-gallon tank, remote and touch control, and 15 to 20 ft/s airflow according to the listing. A good low-cost option for a bedroom in dry air.

WICOLO Windowless Portable Cooler

3-gallon tank, 6 speeds, a 12-hour timer and a 16 ft remote. The tank size gives it longer run time than most compact coolers.

FO-KOKO 5200 BTU Camping AC

Sold as a windowless AC for tents, RVs and vans with a 400 W low power draw in the listing. Verify how it exhausts heat and what cooling you get before buying.

Deco-natural Evaporative Air Cooler

9L tank, 6 ice packs, 2 hour timer and 3 speeds. A compact personal cooler for a desk or bedside.

How We Chose

This guide is research-based. We did not personally use these products. We compared manufacturer pages, retailer listing details and independent resources, with a focus on cooling ratings (SACC, DOE, CFM), tank sizes, coverage claims and power draw. Where a figure comes from owner discussions rather than the manufacturer, we say so. Where it is missing, we mark it as not listed.

We split the list into two honest categories: compressor portable ACs that need an exhaust vent, and evaporative coolers that need no vent. We limited each brand to a single main pick, covered a range of price tiers and favored products that are currently sold.

Buying Guide

Know which kind of unit you are buying

A compressor portable AC cools and dehumidifies, but it must exhaust hot air through a hose. An evaporative cooler needs no hose but depends on dry air. Products labeled ventless or windowless air conditioners are usually evaporative coolers. If you live in a humid region, a ventless unit will often disappoint, because there is little room for water to evaporate.

Use SACC or DOE, not the marketing BTU

ASHRAE ratings can be nearly double the DOE or SACC figure. A 12,000 BTU ASHRAE unit like the DREO 515S is 8,000 BTU under DOE, and a 10,000 BTU BLACK+DECKER is 5,500 BTU SACC. A common rule of thumb is about 20 BTU of cooling per square foot, so 5,500 BTU SACC fits roughly 275 sq ft of shaded space, not the full 450 sq ft in the listing.

Check CFM and tank size for evaporative coolers

CFM measures airflow. About 1,300 CFM suits a small to medium room or a patio, while 2,500 CFM is for larger or open areas. A tank of 4.8 gallons runs a few hours on high, an 8-gallon tank runs longer, and a 1.5-gallon tank needs frequent refills.

Plan for power

A worked example: a 900 W compressor AC on a 1,000 Wh power station gives roughly one hour of runtime, or a bit less once you account for inverter losses. An 82 W evaporative cooler on the same station runs for about 12 hours, or roughly 10 hours after losses. For generators, add starting surge: a rule of thumb is two to three times running watts for compressor units, so a 900 W AC needs 1,800 to 2,700 W of starting capacity. Always check the nameplate.

Venting tips for portable ACs

Keep the hose as short and straight as possible, seal the gaps around the window kit with weatherstripping and insulate the hose if the room is hot. Poor venting can cut cooling noticeably, and heat leaking back in is why SACC is lower than ASHRAE.

Quick decision table

Sizing a Generator or Power Station for Cooling

Start by writing down the running watts of each cooler or AC and add the largest starting load. If you also need a fridge or lights, add those too. A 2,000 W inverter generator can usually run a single 900 W portable AC with margin, while a small 300 W unit can only manage evaporative coolers like the 82 W Hessaire. Fuel use depends on load, so a lighter load lets many inverter generators throttle down and run longer on the same tank.

For a power station, divide the battery capacity in watt-hours by the watts you plan to draw, then multiply by about 0.85 to allow for inverter losses. That is why an evaporative cooler is so appealing for outages: the same battery lasts roughly ten times longer.

Placement, Noise and Water Use

Place a compressor portable AC near a window so the hose stays short, and leave a few inches of clearance around the unit for air intake. Place an evaporative cooler where air can enter the room freely, ideally with a window or door cracked open on the opposite side so humid air can leave. Putting a swamp cooler in a closed room is the most common reason people think it does not work.

Noise matters in bedrooms. The Hessaire MC18M lists 53.4 dB, similar to a quiet conversation, while compressor units add the hum of the compressor on top of fan noise. Look for a listed decibel rating and a night mode if sleep is the goal. Water use is modest, since an evaporative cooler uses about a gallon or two an hour on high depending on its size, so plan your refill routine around the tank size you choose.

Common Mistakes With Ventless and Portable Cooling

• Buying a ventless unit for a humid climate. Evaporative cooling needs dry air.
• Trusting ASHRAE BTU. Compare SACC or DOE figures.
• Skipping sealing around the window kit. Gaps let hot air back in.
• Undersizing the generator. Compressor ACs need extra capacity at startup.
• Forgetting maintenance. Clean filters and pads, and drain tanks before storage.

Frequently Asked Questions

Can a portable air conditioner work without a vent?

No true compressor air conditioner works without exhausting heat. Products sold as ventless are usually evaporative coolers, which cool differently and work best in dry air.

What is the best portable AC vent setup?

Use the included window kit, keep the hose short and straight, seal the gaps and avoid long bends. Insulating the hose can improve cooling in hot rooms.

How many watts does a portable AC use?

Many 10,000 BTU units draw roughly 900 to 1,200 W while cooling, and the startup surge can be higher. Check the rating label for your model.

Can I run a portable AC on a generator?

Yes, if the generator can supply the starting surge as well as the running watts. A common guideline is two to three times running watts for compressor units.

Do evaporative coolers work in humid areas?

Not well. They rely on evaporation, so humid air limits the cooling and may make the room feel damp.

What does SACC mean?

SACC stands for seasonally adjusted cooling capacity. It’s the more realistic rating because it accounts for heat leaking back in.

How big a room can a swamp cooler cool?

Manufacturers list ranges, such as 500 sq ft for the Hessaire MC18M. In practice, results depend on climate, airflow and ventilation.

Which One Should You Buy?

If you live somewhere dry and want the lowest power draw, buy the Hessaire MC18M. If you need genuine air conditioning in a bedroom, choose the DREO 515S for quiet smart cooling, the BLACK+DECKER for a clearly stated SACC rating, or the Midea for app scheduling and a higher SACC. For large spaces, the SereneLife cooler moves a lot of air, and the EXNOS suits a small room or desk.

Match the unit to your climate and your power source first, then fine-tune the rest. If you plan to run it on a generator or power station, write down the running watts and the startup surge before you buy.

Sources

• Hessaire manufacturer product pages for the MC18M
• DREO manufacturer product pages for the AC515S
• BLACK+DECKER portable air conditioner product information
• Midea portable air conditioner product information
• U.S. Department of Energy portable air conditioner efficiency guidance

Last updated: October 2026