📏 Sizing Guide: Is 11,800 BTUs Right for Your Space?
🏠 Introduction: Why Choosing the Right BTU Rating Matters
Every summer, thousands of homeowners buy air conditioners that aren’t quite right for their space — either too weak to keep up or too powerful to run efficiently. I made that mistake once, and it cost me in higher bills and constant cycling noise.
That’s why when I upgraded to the Amana 11,800 BTU 115V Through-the-Wall Air Conditioner, I spent time understanding exactly how BTUs (British Thermal Units) affect cooling comfort. It turns out, getting the size right is the single biggest factor in comfort, efficiency, and long-term durability.
If your space is 400–550 square feet, the Amana 11,800 BTU unit might be your perfect fit. But before you order, let’s take a deep dive into how BTUs work, how to calculate your needs, and what factors can nudge that number up or down.
🔢 What Are BTUs — and Why Should You Care?
A BTU measures how much heat an air conditioner can remove from a room per hour.
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1 BTU = the energy required to raise (or lower) 1 pound of water by 1°F.
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So, an 11,800 BTU AC can pull 11,800 BTUs of heat out of your room every hour.
In simpler terms, BTUs are your AC’s horsepower. Too few BTUs and your unit runs endlessly, struggling to cool. Too many, and it blasts cold air too fast — cooling the air but not removing humidity. The result? A clammy, uncomfortable space.
📘 Further Reading:
📐 Step 1: Measure Your Room’s Square Footage
Before anything else, grab your tape measure.
Formula:Length (ft) × Width (ft) = Square Footage
Now match your room’s square footage to the general BTU guidelines:
| Room Size (sq. ft.) | Recommended BTUs | Ideal For |
|---|---|---|
| 150–250 | 6,000–7,000 | Small bedrooms |
| 250–350 | 8,000–9,000 | Home offices, dens |
| 350–450 | 10,000–11,000 | Medium bedrooms |
| 450–550 | 11,800–12,000 | Large rooms, small apartments |
| 550–700 | 13,000–14,000 | Open living rooms |
If your room lands between 450 and 550 sq. ft., the Amana 11,800 BTU model is likely your Goldilocks zone — not too weak, not too strong.
🧱 Step 2: Look Beyond Square Footage — Room Conditions Matter
Sizing is about more than square footage. Real-world conditions can alter how much cooling your space actually needs. Let’s walk through what to factor in.
🪟 1. Windows & Sun Exposure
Windows act like radiant heaters in summer.
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Add 10% BTUs for large, south- or west-facing windows.
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Reduce by 10% for shaded rooms or those facing north.
💡 Mike’s Note: My living room has two large west-facing windows. Without adjusting for sunlight, my 10,000 BTU unit struggled daily around 3 PM. Upgrading to 11,800 BTUs solved the problem instantly.
🌞 2. Ceiling Height
Most BTU charts assume an 8-foot ceiling. If yours is higher, you’re cooling more air volume.
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Add 10% BTUs for ceilings over 9 feet.
🧍 3. Number of Occupants
Each person adds roughly 600 BTUs/hour of body heat.
Add that for every additional person beyond two.
For example, a 500 sq. ft. living room with four family members should have at least 12,800 BTUs.
🍳 4. Appliances & Electronics
Kitchens, home theatres, and offices produce heat.
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Add 4,000 BTUs for rooms with heavy appliance or computer use.
Example: A 500 sq. ft. kitchen might need closer to 14,000 BTUs — meaning you’d want to move beyond a 115V system into a 230V option.
🧱 5. Insulation Quality
Older homes, garages, or converted attics often leak air.
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Add 10–15% BTUs for poor insulation.
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Newer energy-efficient builds may subtract 10%.
📘 Further Reading:
🌎 Step 3: Adjust for Climate Zone
The U.S. Department of Energy divides regions into eight climate zones, each affecting how hard your AC works.
| Zone | Example Regions | Adjustment |
|---|---|---|
| 1–2 | Florida, Texas, Arizona | +15% BTUs |
| 3–4 | Midwest, Carolinas | +5% BTUs |
| 5–6 | Northeast | Standard |
| 7–8 | Upper Midwest, Pacific NW | -10% BTUs |
If you’re cooling a 500 sq. ft. room in Texas, that +15% brings your need to roughly 13,500 BTUs.
If you’re in Michigan, 11,800 BTUs is spot-on.
📘 Further Reading:
🧮 Step 4: Real-World Room Examples
Let’s look at how this plays out in practice.
🛏 Bedroom (450 sq. ft.)
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Two occupants
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Moderate sunlight
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Good insulation
✅ Ideal Range: 10,500–11,800 BTUs
💡 Perfect for the Amana 11,800 BTU.
🖥 Home Office (350 sq. ft.)
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Two computers, minimal sun
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Single occupant
✅ Ideal Range: 9,000–9,500 BTUs
⚠ Slightly smaller than Amana’s output, but can run in Eco or Energy Saver mode.
🍿 Living Room (500 sq. ft.)
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Four people, open layout
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South-facing windows
✅ Ideal Range: 12,500–13,000 BTUs
🟢 Amana 11,800 BTU handles this efficiently while staying quiet.
🧺 Basement (550 sq. ft.)
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Minimal sunlight, humid
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Cooler baseline temp
✅ Ideal Range: 10,500–11,500 BTUs
🟢 Amana’s unit excels at humidity removal, even if slightly oversized.
⚙️ Step 5: The Role of EER & CEER Ratings
Even the perfect BTU rating won’t save energy if your AC is inefficient.
🧩 What’s the Difference?
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EER (Energy Efficiency Ratio): Cooling output ÷ power input (watts)
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CEER (Combined Energy Efficiency Ratio): Real-world rating including standby power
The Amana 11,800 BTU model scores around EER 10.6, CEER 10.3+, which is solidly above industry average.
⚡ The higher the number, the less electricity you use for the same comfort.
📘 Further Reading:
💡 Step 6: Comparing BTU Options Side-by-Side
| Model | BTU Rating | Room Size | Voltage | Ideal For |
|---|---|---|---|---|
| Amana 9,200 BTU | 9,200 | 300–400 sq. ft. | 115V | Bedrooms |
| Amana 11,800 BTU | 11,800 | 450–550 sq. ft. | 115V | Living rooms, dens |
| Amana 14,200 BTU | 14,200 | 600–700 sq. ft. | 230V | Large rooms, offices |
If your space falls mid-range, stick to 11,800 BTUs. Jumping up unnecessarily increases noise, cost, and humidity issues.
🚫 The Problem with Oversizing
Bigger isn’t always better.
An overly powerful AC cools the air too quickly without removing humidity. You’ll end up cold and sticky. This short-cycling also:
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Raises electricity bills
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Wears out compressors faster
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Causes uneven cooling
That’s why I always tell homeowners — aim for “just right,” not “overkill.”
🧰 Step 7: Check Wall Sleeve Compatibility
Through-the-wall units rely on sturdy sleeves for secure installation.
The Amana 11,800 BTU typically fits 26" width × 15.5" height × 16" depth sleeves, like Amana WS900D.
If you’re replacing an older unit:
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Check sleeve dimensions before ordering.
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Seal any gaps with foam gasket kits.
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Clean out debris and caulk edges to prevent air leakage
📘 Further Reading:
💵 Step 8: Energy Cost Breakdown
The Amana 11,800 BTU uses about 1,113 watts/hour at EER 10.6.
At an average U.S. rate of $0.15/kWh, running it:
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8 hours/day = $1.33/day
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30 days = $39.90/month
That’s roughly $120–150 per summer, depending on your usage — far lower than comparable portable or window units.
🌬️ Step 9: Airflow, Dehumidification & Noise Control
The Amana unit doesn’t just cool — it manages humidity and airflow beautifully.
Key Performance Stats:
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Dehumidification: 2.7 pints/hour
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Airflow Rate: ~260 CFM (cubic feet/minute)
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Noise Level: 56–60 dB (quiet conversation level)
Mike’s Pro Tips:
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Mount slightly higher on the wall for even air distribution.
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Keep 2 feet of clearance on both sides of the sleeve.
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Use the “Dry” mode on muggy days for gentle cooling.
🧊 Step 10: Seasonal Performance in Real Climates
☀️ Hot & Humid States (e.g., Florida)
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The Amana handles temperatures up to 115°F with proper sleeve venting.
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Use “Energy Saver” mode during peak afternoon hours.
🍃 Mild Climates (e.g., Oregon)
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The unit runs quietly in moderate temps.
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Eco mode keeps humidity consistent without overcooling.
🏜 Dry Regions (e.g., Arizona)
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Low humidity helps the system run efficiently.
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Regularly clean coils to avoid dust buildup.
🧩 Step 11: When to Size Up or Down
| Situation | Adjustment | New BTU Target |
|---|---|---|
| South-facing large windows | +10–15% | 13,000–13,500 |
| Shaded basement | -10% | 10,500 |
| Two occupants, good insulation | Standard | 11,800 |
| Four occupants, open floor plan | +15% | 13,500 |
If your result stays within ±15% of 11,800 BTUs, this unit remains an efficient, reliable choice.
⏳ Step 12: Lifespan & Efficiency Over Time
With regular care, the Amana 11,800 BTU can last 12–15 years.
Follow this seasonal routine:
| Season | Task |
|---|---|
| Spring | Clean filter, inspect coils, reseal sleeve |
| Summer | Rinse fins, check thermostat accuracy |
| Fall | Vacuum dust, cover the exterior vent |
| Winter | Store remote, check drainage for debris |
A little seasonal upkeep keeps performance consistent — and your utility bills low.
📘 Further Reading:
✅ Final Verdict: Who Should Buy the 11,800 BTU Amana?
If your space is:
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400–550 sq. ft.
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Moderately sunny
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Occupied by 2–4 people
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Uses a standard 115V outlet
Then the Amana 11,800 BTU Through-the-Wall Air Conditioner is one of the best all-around choices you can make.
It’s:
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Energy-efficient
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Quiet
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Easy to install
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Perfectly balanced between size and performance
“I installed this unit in my 480 sq. ft. den last summer, and it’s been rock-solid. It cools fast, runs quietly, and keeps humidity in check — exactly what you want from a through-the-wall AC.”
— Mike Sanders
🧾 Quick Recap: BTU Sizing Formula
(Room Square Footage × 25) + Adjustments (People, Sun, Appliances, Insulation)
≈ Ideal BTU Output
Example:
500 sq. ft. × 25 = 12,500
– 10% (shaded) = 11,250
✅ Amana 11,800 BTU = Perfect Fit
🖼️ Suggested Infographic: “Room Size vs. BTU Chart for Through-the-Wall ACs”
Sections:
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Room area visual (200–700 sq. ft.)
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Icons for insulation, sunlight, and ceiling height
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“Mike’s Rule of Thumb” callout:
“If you’re within 10% of your target BTUs, you’re in the sweet spot.”
In the next blog, we shall learn more aboutInstallation Guide: What Mike Learned Installing His Amana Wall AC
