Do 15,000 BTU Through-the-Wall ACs Work for Year-Round Comfort? Heating Options Explained

Hi, I’m Samantha! When I shopped for my 15,000 BTU through‑the‑wall AC, I wanted more than summer relief — I wanted a solution that could keep my home comfortable in all four seasons. But as I quickly discovered, not all TTW (through‑the‑wall) units are created equal. Some provide only cooling, while others include electric heat or even a heat pump.

In this guide, I’ll share everything I learned about whether a 15,000 BTU TTW AC can truly deliver year‑round comfort. We’ll cover:

• Cooling performance ✅

• Heating options 🔥

• Efficiency & operating costs ⚡

• Climate considerations 🌍

• Installation & safety 🛠️

• My personal tips 💡

By the end, you’ll know which type of unit is right for your home — and whether you’ll need backup heating this winter.

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❄️ 1. Cooling: The Easy Part

Let’s start with the obvious: cooling is what TTW ACs do best.

How Much Space Does 15,000 BTUs Cover?

According to Energy.gov, a 15,000 BTU air conditioner is ideal for:

• 550–850 sq ft rooms (depending on insulation & ceiling height)

• Large living rooms, master suites, or open‑concept areas

💡 Samantha’s note: My 15,000 BTU unit keeps my 720‑sq‑ft family room cool even during heat waves.

Why Through‑the‑Wall Over Window Units?

• More permanent & secure installation

• Better insulation (less air leakage)

• Doesn’t block your view or window light

• Quieter in most cases

🔗 Resource: The Furnace Outlet highlights how TTW ACs often outperform same‑sized window units due to better sealing.

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🔥 2. Heating Options for Through-the-Wall ACs

Here’s where things get interesting: not all TTW ACs provide heat. Let’s break down your options.

1) 🔌 Electric Resistance Heat

• Uses built‑in electric heating coils.

• Works like a giant space heater inside your AC.

Pros:

• Affordable upfront (units often $100–$200 cheaper than heat pumps).

• Simple design with fewer moving parts.

Cons:

• Expensive to run in winter.

• Converts electricity to heat at a 1:1 ratio (not energy‑efficient).

💡 Example: A 15,000 BTU TTW AC with a 5 kW heater can cost $120–$160/month to heat a large room in winter.

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2) ♻️ Heat Pump Through-the-Wall Units

• Works like a reversible AC: pulls heat from outdoors in winter.

• 2–3x more efficient than electric resistance.

Pros:

• Lower winter bills compared to resistance heat.

• Provides cooling in summer, heating in winter.

Cons:

• Loses effectiveness when temps drop below 25–30 °F.

• May need backup heating in northern states.

💡 Samantha’s note: I live in a moderate climate, and my TTW heat pump handles 90% of the winter just fine — I only need a small space heater during deep freezes.

🔗 Energy Star shows certified models that balance cooling and heating efficiency.

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3) 🌡️ Supplemental Heating Options

If you go the heat pump route in colder climates, you’ll want backup heat:

• Electric baseboard heaters

• Gas furnace

• Infrared or ceramic space heater

💡 Samantha’s tip: For my guest bedroom, I use a TTW heat pump + a $60 ceramic space heater on the coldest nights — works like a charm!

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⚡ 3. Energy Use & Efficiency

Heating and cooling efficiency isn’t just about comfort — it directly affects your monthly bills.

Key Metrics to Watch

• EER (Energy Efficiency Ratio) — cooling efficiency at 95 °F.

• CEER (Combined EER) — real‑world efficiency including standby power.

• SEER2 (Seasonal Energy Efficiency Ratio 2) — updated 2023 standard for cooling across a season.

For heating, heat pumps are rated with HSPF2 (Heating Seasonal Performance Factor 2).

Cost Comparison

Let’s compare a 15,000 BTU TTW AC:

(Based on $0.14/kWh and moderate U.S. winter climate)

🔗 LearnMetrics explains CEER and why it’s key for real‑world cost predictions.

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🏙️ 4. Climate Considerations

The best choice depends heavily on where you live.

☀️ Warm & Mild Winters (South & West Coast)

• A TTW heat pump model may cover all your heating and cooling needs.

• Rarely need supplemental heat.

🌤️ Moderate Climates (Mid‑Atlantic, Pacific Northwest)

• Heat pumps handle most of the winter.

• Supplemental heat only needed during cold snaps.

❄️ Cold Climates (Midwest, Northeast)

• Heat pump TTW units still useful but need backup heat.

• Electric resistance models work but cost more long‑term.

🔗 This Old House suggests pairing TTW heat pumps with other systems in colder regions.

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🛠️ 5. Installation Notes for Heating Units

When installing a TTW AC with heat:

• Electrical Needs:

  • Most 15,000 BTU cooling‑only units run on 115V.

  • Heating models often require 230V and a dedicated 20A circuit.

• Wall Sleeve Compatibility: Ensure the sleeve supports drainage in both modes.

• Weatherproofing: Use caulk and flashing to seal against drafts.

💡 Samantha’s lesson: I underestimated the electrical side — my 230V upgrade added $300+ to the project.

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💡 6. Samantha’s Pro Tips

• Don’t assume all TTW ACs heat — check the specs carefully.

• Look for Energy Star heat pump models for better efficiency.

• If you’re in a colder state, plan for backup heat.

• Budget for electrical work if your unit requires 230V.

• Seal the sleeve properly to prevent drafts in winter.

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✅ Samantha’s Final Verdict

So, do 15,000 BTU through‑the‑wall ACs work for year‑round comfort?

Yes — if you choose the right type:

• ✅ Cooling‑only: Great for hot summers, no winter use.

• ✅ Electric resistance heat: Reliable but costly in cold regions.

• ✅ Heat pump models: The best balance for mild to moderate climates, with backup heat for deep winter.

💡 Samantha’s bottom line:
“For true year‑round comfort, a heat pump TTW AC is the way to go. Just make sure you plan for supplemental heating if your winters dip below freezing.”

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In the next topic we will know more about: Best Brands Compared: GE vs. LG vs. Friedrich in the 15,000 BTU Category