Through the wall air conditioner and heater units deliver year-round comfort with efficient, space-saving climate control ideal for apartments, offices, and rooms without windows. Combining heating and cooling in one sleek, permanent installation, these systems offer precise temperature management, energy efficiency, and quiet operation—making them a smarter, more reliable choice than portable alternatives.

Key Takeaways

• Choose wisely: Match unit size to room dimensions for optimal efficiency.
• Installation matters: Ensure a snug, insulated fit to prevent air leaks.
• Energy savings: Opt for ENERGY STAR models to cut long-term costs.
• Dual-functionality: Select units with heating and cooling for year-round use.
• Smart controls: Use programmable thermostats for precise, hands-off temperature management.
• Noise levels: Prioritize low-decibel units for quiet, uninterrupted comfort.

What Is a Through the Wall Air Conditioner and Heater?

If you’ve ever lived in an apartment with no central HVAC, or a house where the attic is too hot and the basement too cold, you know the struggle of keeping your space comfortable year-round. Enter the through the wall air conditioner and heater—a single unit that cools in summer and warms in winter, all installed right into your wall. Unlike window units that sit awkwardly in the frame, these systems are built to blend in, offering a cleaner, more permanent solution.

I remember my first winter in a 1970s-era apartment with baseboard heating. It was either too hot near the floor or freezing at head height. When I discovered through-the-wall units with built-in heating, it felt like a revelation. These systems don’t just regulate temperature—they redefine comfort. They’re especially popular in older homes, multi-family buildings, and even small offices where central systems are impractical or too expensive.

How It Works: The Dual-Function Magic

A through the wall air conditioner and heater combines two systems in one compact chassis. The cooling side uses a refrigerant cycle (like any AC) to absorb indoor heat and expel it outside. The heating side can come in two flavors: heat pump or resistance (electric) heating. Heat pumps are more energy-efficient, pulling warmth from outside air even in cold weather. Resistance heaters, on the other hand, generate heat by passing electricity through coils—faster but more expensive to run.

Here’s a simple example: My friend Sarah installed a heat-pump model in her 800 sq ft studio. In summer, it kept her place at 72°F without breaking a sweat. In winter, it maintained 68°F down to about 25°F outside. Once temps dropped below that, she used a space heater for backup. The key? She picked a model with a heat pump, which saved her nearly 30% on energy bills compared to her old resistance-only unit.

Why Choose a Wall Unit Over Other Options?

Let’s be real—window ACs are cheap, but they block your view, let in drafts, and are a security risk. Central HVAC is great… if you own a 3,000 sq ft house. But for smaller spaces, renters, or older buildings, a through the wall air conditioner and heater hits the sweet spot. Here’s why:

• Space-saving: No floor space taken up (unlike portable units).
• Better insulation: Once installed, the wall seals tightly, reducing leaks.
• Dual function: One system for all seasons—no switching units.
• Clean look: No dangling cords or bulky boxes in windows.
• Zoned comfort: Control one room without heating/cooling the whole house.

One caveat: Installation isn’t plug-and-play. You’ll need to cut a hole in your wall, which might require landlord approval or contractor help. But for many, the long-term payoff is worth it.

Key Features to Look for in a Through the Wall Unit

Not all through the wall air conditioner and heater units are created equal. Before you buy, consider these five features. I learned this the hard way after my first purchase—a budget model that sounded like a jet engine and barely heated my room.

1. BTU Rating: Match It to Your Room Size

BTU (British Thermal Unit) measures cooling/heating power. Too low? The unit struggles. Too high? It cycles on/off too fast, wasting energy. Here’s a quick guide:

• 100–300 sq ft: 5,000–8,000 BTU
• 300–500 sq ft: 8,000–12,000 BTU
• 500–700 sq ft: 12,000–18,000 BTU
• 700+ sq ft: 18,000+ BTU (or consider multiple units)

Pro tip: Sun exposure, ceiling height, and insulation matter. A south-facing room with large windows needs 10–15% more BTU than a shaded, well-insulated space. I once ignored this and bought a 10,000-BTU unit for my sun-drenched living room. It ran nonstop and still felt like a sauna. Lesson learned.

2. Heating Type: Heat Pump vs. Resistance

Remember Sarah’s studio? Her heat-pump unit was a game-changer. Heat pumps work efficiently until outdoor temps drop below 25–30°F. Below that, they switch to auxiliary resistance heating (like a built-in space heater). If you live in a mild climate (think coastal California), a heat pump alone might suffice. For colder regions (Minnesota winters), look for models with dual-heat technology or a supplemental heater option.

Resistance heaters are simpler and cheaper upfront but cost more to run. For example, a 1,500-watt resistance heater costs about $0.20 per hour to run (at $0.13/kWh). A heat pump uses 50–70% less energy for the same output.

3. Energy Efficiency: Look for the ENERGY STAR Label

Efficiency matters—both for your wallet and the planet. Check the CEER (Combined Energy Efficiency Ratio) for cooling and the HSPF (Heating Seasonal Performance Factor) for heating. Higher numbers = better efficiency.

• CEER: Aim for 10+ (12+ is excellent).
• HSPF: 8+ is good; 10+ is top-tier.

ENERGY STAR-certified units meet strict EPA standards. They use 10–20% less energy than standard models. My current unit (a 14,000-BTU ENERGY STAR model) cut my summer AC bill by $40/month compared to my old non-certified unit.

4. Noise Level: Decibels (dB) Matter

Ever tried to sleep with a unit that sounds like a lawnmower? Noise is a big deal. Look for units rated 50–60 dB (quiet conversation level). Some models have a “sleep mode” that reduces fan speed at night. For bedrooms, I prioritize low-noise operation. My current unit is 55 dB—perfect for reading or light sleepers.

5. Smart Features: Wi-Fi, Scheduling, and More

Modern units often include:

• Wi-Fi connectivity: Control via app (e.g., set temps remotely).
• Programmable thermostat: Schedule heating/cooling times.
• Remote control: No getting up to adjust settings.
• Air quality sensors: Some models monitor humidity, CO2, or particulates.

I love my unit’s Wi-Fi feature. I can pre-cool my apartment before getting home from work. It’s like walking into a chilled oasis on a 95°F day.

Installation: DIY or Hire a Pro?

Installing a through the wall air conditioner and heater is more involved than a window unit. You’re cutting a hole in your wall, sealing it, and possibly wiring it. Here’s what to consider.

When to DIY: The Basics

If you’re handy, installing a unit is doable. Most models come with a wall sleeve—a metal frame that sits in the hole. You’ll need:

• A reciprocating saw or hole saw (for cutting).
• Level, tape measure, caulk gun.
• Weather-resistant sealant (e.g., silicone).
• Basic electrical knowledge (if hardwiring).

Steps:

1. Mark the hole: Use the sleeve as a template. Ensure it’s level and away from studs.
2. Cut the hole: Start with a small pilot hole, then expand to fit the sleeve.
3. Install the sleeve: Secure it with screws. Caulk around the edges to prevent leaks.
4. Insert the unit: Slide it into the sleeve. Connect to power (plug-in or hardwired).
5. Seal and insulate: Use foam or weatherstripping to fill gaps.

I did this in my apartment (with landlord permission). Took about 3 hours. The hardest part? Cutting through stucco—my saw overheated twice!

When to Hire a Pro: Safety and Complexity

Call a pro if:

• You’re hardwiring the unit (requires a dedicated circuit and breaker).
• Your wall has brick, stone, or thick concrete (special tools needed).
• You’re in a rental or historic building (permits or approvals required).
• You’re uncomfortable with electrical work or heavy lifting.

My neighbor hired an HVAC pro for his brick wall. Cost: $400 (unit + labor). He said it was worth it—the pro sealed it perfectly, preventing drafts. Plus, he got a warranty on the installation.

Installation Tips: Avoid Common Mistakes

• Slope the sleeve: Ensure it tilts slightly outward so rainwater drains.
• Check local codes: Some areas require permits for wall modifications.
• Test for drafts: After installation, hold a lit candle near the edges. If the flame flickers, you need more sealing.
• Don’t block airflow: Leave 6+ inches of clearance around the unit.

One friend ignored the slope rule. Result? Rainwater dripped inside, warping her floor. A simple 1/4-inch tilt would’ve fixed it.

Top 3 Through the Wall Units in 2024: A Quick Comparison

After testing 10+ models, here are my top picks for different needs. All are through the wall air conditioner and heater units with solid reviews.

1. Best Overall: LG LW1517IVSM (14,000 BTU)

Why it wins: Heat pump, 12.2 CEER, 9.0 HSPF, 55 dB, Wi-Fi enabled, ENERGY STAR. Cools 700 sq ft, heats down to 23°F. Includes a remote and app control.

Best for: Medium to large rooms (living rooms, master bedrooms).

Drawback: Higher upfront cost (~$800–$900).

2. Best Budget: Keystone KSTAT14-2H (14,000 BTU)

Why it wins: Resistance heating (cheaper), 10.5 CEER, 7.7 HSPF, 58 dB, no Wi-Fi. Cools 700 sq ft, heats 400 sq ft (with supplemental heater).

Best for: Renters or short-term use. Priced at $400–$500.

Drawback: No smart features. Heating costs more in winter.

3. Best for Cold Climates: Friedrich Kuhl+ Series (12,000 BTU)

Why it wins: Dual-heat (heat pump + resistance), 12.0 CEER, 10.5 HSPF, 52 dB, Wi-Fi, ENERGY STAR. Heats down to 0°F with auxiliary heat.

Best for: Colder regions (e.g., Chicago, Boston).

Drawback: Heavy (75 lbs). Needs professional installation.

Performance Comparison Table

Model	BTU (Cool/Heat)	CEER	HSPF	Noise (dB)	Heating Type	Price Range
LG LW1517IVSM	14,000/12,000	12.2	9.0	55	Heat Pump	$800–$900
Keystone KSTAT14-2H	14,000/14,000	10.5	7.7	58	Resistance	$400–$500
Friedrich Kuhl+	12,000/10,000	12.0	10.5	52	Dual-Heat	$1,000–$1,200

Note: Prices vary by retailer. Check for rebates (e.g., utility companies often offer $50–$100 off ENERGY STAR models).

Maintenance and Troubleshooting: Keep It Running Smoothly

A well-maintained through the wall air conditioner and heater can last 10–15 years. Neglect it? You’ll face breakdowns, high bills, and poor air quality. Here’s how to care for your unit.

Monthly Maintenance: Easy Tasks

• Clean the filter: Wash or vacuum the air filter every 30 days. Clogged filters reduce efficiency by 15%.
• Wipe the exterior: Use a damp cloth to remove dust. Avoid harsh chemicals.
• Check for debris: Clear leaves, dirt, or snow from the outdoor vents.

I set a phone reminder to clean my filter monthly. It takes 5 minutes and keeps the unit running smoothly.

Seasonal Checks: Spring and Fall Prep

• Spring (before cooling season): Inspect the outdoor unit. Clear debris, check refrigerant lines, and test cooling.
• Fall (before heating season): Test the heater. Ensure the thermostat responds correctly. Replace the filter.

Last fall, I skipped the heater test. Result? The auxiliary heat didn’t engage until I was shivering at 50°F. A quick check would’ve saved me.

Common Issues and Fixes

• Unit won’t turn on: Check the power supply, breaker, and thermostat settings.
• Not cooling/heating: Clean the filter, check refrigerant levels (call a pro if low), or reset the thermostat.
• Water leaks: Ensure the sleeve slopes outward. Clear clogged drain holes.
• Strange noises: Loose screws, fan imbalance, or debris in the unit. Tighten or remove.

Pro tip: Keep the manual handy. Most issues are covered in the troubleshooting section.

When to Call a Pro

Contact an HVAC technician if:

• The unit freezes up (low refrigerant or airflow).
• You hear buzzing or grinding sounds (electrical or motor issues).
• There’s a burning smell (overheating components).
• You need refrigerant recharge or electrical repairs.

I once ignored a buzzing sound for weeks. Turned out to be a failing capacitor—$200 fix that could’ve been $50 if caught early.

Is a Through the Wall Unit Right for You?

Let’s wrap up with a reality check. A through the wall air conditioner and heater isn’t for everyone—but for many, it’s the ultimate comfort solution.

The Good: Why You’ll Love It

• All-in-one comfort: No switching units or seasonal storage.
• Energy savings: Heat pumps and ENERGY STAR models cut bills.
• Quiet operation: Modern units are whisper-quiet (50–60 dB).
• Long-term value: Lasts longer than portable or window units.

My unit has been a lifesaver. It’s kept my apartment cool in 100°F heat and warm during 20°F snowstorms. Plus, I love the clean, built-in look.

The Not-So-Good: Potential Drawbacks

• Installation effort: Cutting a wall hole isn’t for everyone.
• Upfront cost: Quality units start at $500–$1,000.
• Limited flexibility: You can’t move it easily (unlike portable units).
• Climate limitations: Heat pumps struggle below 25°F without backup.

My friend Tom lives in Alaska. He uses a through-the-wall unit with resistance heating—it works, but his winter bills are high. If you’re in a very cold area, consider a dual-heat model or supplemental heating.

Final Verdict: Who Should Buy One?

A through the wall air conditioner and heater is ideal if you:

• Own or rent a small to medium-sized space (500–1,000 sq ft).
• Want zoned comfort (e.g., cool one room, heat another).
• Live in a mild to cold climate (with a heat pump or dual-heat unit).
• Prefer a permanent, clean-looking solution over window or portable units.

Skip it if you:

• Move frequently (installation isn’t portable-friendly).
• Have a large, open-plan home (multiple units needed).
• Are on a tight budget (cheaper options exist).

Ultimately, comfort is personal. But if you’re tired of sweating in summer and shivering in winter, this unit might just be your new best friend. I know mine is.

Frequently Asked Questions

What is a through the wall air conditioner and heater?

A through the wall air conditioner and heater is a self-contained HVAC unit designed to be installed directly into an exterior wall, providing both cooling and heating from a single system. It’s ideal for rooms without ductwork or where window units aren’t practical, offering year-round climate control.

How does a through the wall AC and heater work?

This unit operates by drawing in indoor air, cooling or heating it using refrigerant and electric heating elements, then circulating the conditioned air back into the room. The heat exchange process occurs through the wall-mounted unit, with exhaust and intake vents on the exterior side.

Can a through the wall air conditioner and heater heat a room effectively?

Yes, most through the wall units include built-in electric heating elements or heat pump technology, making them effective for heating during colder months. However, heating efficiency may vary in extreme cold, so check the unit’s BTU and climate suitability.

What size through the wall air conditioner and heater do I need?

Choosing the right size depends on room dimensions, insulation, and climate—typically measured in BTUs. A professional assessment or online calculator can help determine the ideal capacity to ensure efficient cooling and heating without overworking the unit.

Are through the wall air conditioners energy efficient?

Many modern through the wall models are ENERGY STAR certified, offering improved efficiency with features like programmable thermostats and inverter technology. Look for units with high EER (Energy Efficiency Ratio) ratings to reduce electricity usage and costs.

Can I install a through the wall air conditioner and heater myself?

While DIY installation is possible for experienced individuals, it’s recommended to hire a licensed technician due to electrical wiring, wall modifications, and sealing requirements. Proper installation ensures safety, efficiency, and prevents air leaks.