Many people think their wall unit or PTAC handles both cooling and heating automatically. The truth? Without an electric heat kit, most systems struggle once outdoor temps dip below 45°F.
This guide explains what a 3.5 kW heater really does, how it transforms a 12,000 BTU PTAC into an all-season comfort system, and how to size it right for your space and climate.
⚙️ Section 1: What Is an Electric Heat Kit?
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Define what a heat kit is: a set of electric heating elements that install directly into a PTAC or air handler.
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Explain that it works like a built-in space heater, converting electrical energy into heat.
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Detail components: heating coils, safety limiters, wiring harness, and thermostat integration.
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Clarify that the kit runs independently from the cooling compressor — no refrigerant involved.
Jake says:
“Think of it as your system’s backup plan — the one that kicks in when winter refuses to back off.”
⚡ Section 2: What Does 3.5 kW Mean in Real Terms?
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Convert 3.5 kilowatts to 11,942 BTUs of heating output (using 1 kW = 3,412 BTU).
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Add this to the PTAC’s native 12,000 BTU cooling power to show total effective comfort capacity.
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Example: a 12,000 BTU cooling + 11,942 BTU heating combo = year-round temperature balance for ~450–550 sq ft.
🔗 Reference: U.S. Department of Energy – Heating and Cooling Basics
Jake’s analogy:
“That 3.5 kW heat kit basically doubles your PTAC’s muscle for winter — without adding a separate furnace.”
🌡️ Section 3: How Electric Heat Complements Cooling
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Break down how the PTAC uses reversing airflow and control sequencing to switch between cooling and heating modes.
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In cooling season: refrigerant-based heat removal.
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In heating season: resistive electric elements provide steady warm airflow.
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Explain the benefit: no ducts, no fuel, no outside compressor — just plug-and-play heating for smaller spaces.
🔗 Reference: Energy Star – Packaged Terminal Air Conditioners Overview
Jake explains:
“Your PTAC’s already built to move air — the heat kit just changes what kind of air it’s moving.”
🧮 Section 4: When You Need a 3.5 kW Kit vs. a 2.5 kW or 5 kW
| Room Size | Recommended PTAC | Matching Heat Kit | Example Use |
|---|---|---|---|
| 300–400 sq ft | 9,000–10,000 BTU | 2.5 kW | Small office or bedroom |
| 400–550 sq ft | 12,000 BTU | 3.5 kW | Living room or hotel suite |
| 550–700 sq ft | 14,000–15,000 BTU | 5.0 kW | Large open area |
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Explain that choosing the wrong heat kit can lead to breaker trips or underheating.
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Detail how breaker size and amp draw affect safe operation (3.5 kW typically draws ~15 amps at 240V).
🔗 Reference: National Electrical Code – Heating Equipment Load Calculations
Jake’s tip:
“If your breaker’s popping every time you switch to heat, you’ve probably got a mismatch between wattage and wiring.”
❄️ Section 5: Why Heat Kits Matter in Cold Climates
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Describe how standard PTACs without heat kits rely on the compressor for mild heating — but lose effectiveness below ~40°F.
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The electric element takes over when refrigerant-based heat can’t keep up.
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In colder states (Zone 5 and up), the heat kit keeps rooms warm even during freezes.
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Example: In Maine, a 3.5 kW kit turns a 12,000 BTU PTAC into an effective 24,000 BTU heating system.
Jake says:
“If you’ve ever felt your PTAC blowing lukewarm air in January — that’s your cue you needed a heat kit yesterday.”
🔗 Reference: DOE – Heating Systems for Cold Climates
💡 Section 6: Efficiency and Cost Considerations
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Electric heat kits are nearly 100% efficient at point of use (all energy converts to heat).
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However, they can draw more power than heat pumps — average cost: $0.12–$0.15 per kWh.
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Compare annual heating cost for PTAC + heat kit vs. portable space heaters.
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Stress the safety and integration advantage — heat kits use system thermostats, not unregulated coils.
Jake adds:
“A built-in heat kit costs less to run than three plug-in space heaters — and it’s a lot safer.”
🔗 Reference: Energy.gov – Electric Resistance Heating Explained
🧰 Section 7: Installation & Compatibility Tips
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Walk through how the 3.5 kW kit mounts into the PTAC chassis.
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Mention factory compatibility with Amana Distinctions, GE, and Hotpoint models.
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Emphasize using correct circuit breaker and wire gauge per spec sheet.
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Include safety callout: installation should be performed by a licensed HVAC electrician.
Jake’s advice:
“It’s not a DIY job unless you’ve got a voltmeter, wiring diagram, and nerves of steel. Let a pro handle it.”
🔗 Reference: Amana PTAC Installation Manual – Electric Heat Kit Guidelines
🔌 Section 8: Performance in Real Conditions
Example 1: Midwest Apartment (Zone 4)
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Room: 500 sq ft
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System: Amana 12,000 BTU PTAC
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Add: 3.5 kW heat kit
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Result: Maintains 70°F even during 25°F outdoor temp
Example 2: Hotel Room in Texas (Zone 2)
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Room: 400 sq ft
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System: Same PTAC
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Result: Heat kit activates for short bursts on cold nights, steady comfort with minimal power draw
Jake sums it up:
“The heat kit doesn’t just keep you warm — it keeps your system from overworking itself trying to do something it wasn’t built for.”
🧊 Section 9: 3.5 kW vs. Heat Pump Heating
| Feature | 3.5 kW Electric Heat | Heat Pump Mode |
|---|---|---|
| Works in any temp | ✅ Yes | ❌ Loses efficiency below 40°F |
| Startup cost | Low | Higher |
| Maintenance | Minimal | Requires refrigerant service |
| Response time | Instant heat | Gradual |
| Operating cost | Higher in long winters | Lower overall |
Jake says:
“If you live where snow sticks, a 3.5 kW heat kit is your best friend. If not, stick with the heat pump mode.”
🔗 Reference: Energy Star – Heat Pump vs. Electric Heat Comparison
🧭 Section 10: Jake’s Final Word
“That little 3.5 kW box under your PTAC’s cover is what makes year-round comfort possible. Without it, your system’s only doing half the job.”
Adding a heat kit isn’t about luxury — it’s about preparedness. It lets your PTAC keep up when the seasons shift without relying on space heaters, gas furnaces, or ducted systems.
So the next time you see that “3.5 kW” label on your unit, you’ll know: it’s not just a number. It’s the difference between chilly and comfortable when winter hits.
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In the next topic we will know more about: When to Upgrade: Why Your Old 15,000 BTU Unit Might Be Too Big for Today’s Efficiency Standards
