Heating Options: Through-the-Wall ACs with Heat Pumps vs Electric Heat Strips

Homeowners love to argue about heating options built into through-the-wall ACs. Half the people I meet swear electric heat strips are “more powerful,” and the other half think a heat pump is “only for warm states.” Both groups are wrong in important ways. I’m Jake, and I’m here to bust this entire topic wide open: heat pumps vs electric heat strips is not about opinion; it’s about physics, climate, and your power bill.

Most 12,000 BTU through-the-wall units that can heat will do it one of two ways:

1. Heat pump mode – the same refrigeration cycle used for cooling, but reversed.

2. Electric resistance heat strips – basically a big, glorified toaster jammed inside the air stream.

The myth is that strips “heat better” while pumps are “weak.” The reality is: heat pumps move two to three times more heat per watt than heat strips when conditions are right, but they absolutely have limits in colder climates. Electric heat strips, on the other hand, are perfectly predictable, brutally simple, and brutally expensive to run.

In this guide, Myth-Busting Jake walks you through heat pump versus heat strip efficiency, which climates need which option, a heating performance chart, and clear cost difference examples so you can stop guessing. I’ll also drop 6–7 external placeholder links, like this technical overview page at HVAC Lab, so you can dig deeper if you want.

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1. Heat Pump vs Heat Strip: What’s Actually Going On Inside the Unit?

Before we talk climate, bills, or charts, you need to know what each system is doing under the metal.

1.1 Heat Pump Mode

In heat pump mode, your through-the-wall AC reverses its refrigerant cycle:

• The outdoor coil becomes the evaporator, absorbing heat from outside air.

• The indoor coil becomes the condenser, releasing that heat into your room.

• The compressor and expansion device simply swap roles in terms of direction.

Key point from Data Jake land: the system is moving heat, not creating it. That’s why a heat pump can deliver 200–350 percent “efficiency” in mild winter conditions. For every one unit of electrical energy you feed it, you might get two or three units of heat delivered into your room.

1.2 Electric Heat Strip Mode

Electric heat strips are as simple as they get:

• Current flows through high-resistance heating elements.

• The elements get red-hot.

• The blower moves air across them.

• All the electrical power becomes heat in the air.

Electric resistance is always 100 percent efficient at converting electricity to heat, but never more than that. One unit of electrical energy in equals one unit of heat out. There is no leverage; there is no multiplying effect.

That’s the core myth-buster: heat strips are never more efficient than a heat pump. They may feel “hotter” at the grille because discharge air is warmer, but your meter doesn’t care about feelings.

If you want a schematic-level walkthrough of both systems, a technical overview like Heating Basics gives you pretty diagrams you can pair with this explanation.

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2. Heat Pump vs Heat Strip Efficiency: Numbers, Not Hype

Let’s talk in real numbers, because Myth-Busting Jake doesn’t do vague.

2.1 Heat Pump Efficiency (COP)

Heat pump heating efficiency is described by COP, or Coefficient of Performance:

COP = Heat output (in watts) ÷ Electrical input (in watts)

Example COP values for a decent through-the-wall heat pump:

• At 50°F outside: COP ≈ 3.0

• At 40°F outside: COP ≈ 2.5

• At 32°F outside: COP ≈ 2.0

• At 25°F outside: COP ≈ 1.5

Translated: at 40°F, every 1 kW you buy from the utility might give you 2.5 kW worth of heat into the room. That’s a 250 percent efficiency.

2.2 Heat Strip Efficiency (Always COP ≈ 1.0)

Electric heat strips are brutally simple:

• COP ≈ 1.0

• 1 kilowatt in → 1 kilowatt out

That’s not bad. It’s just not leveraged like a heat pump. If your power is cheap or your climate is extreme, you may still use strips in the right application, but let’s not pretend they’re efficient. They’re not.

2.3 What This Means For Your Bill

If both the heat pump and strip are delivering the same heat output—let’s say 10,000 BTU/hour (~2.93 kW)—then:

• Heat pump at COP 2.5 needs 2.93 ÷ 2.5 ≈ 1.17 kW of electricity.

• Heat strip at COP 1.0 needs 2.93 ÷ 1.0 = 2.93 kW of electricity.

Your strip uses about 2.5 times more power for the same heat.

If electricity costs $0.17/kWh:

• Heat pump: 1.17 kW × $0.17 ≈ $0.20 per hour

• Heat strip: 2.93 kW × $0.17 ≈ $0.50 per hour

That’s the myth-busting headline: the heat pump can cut heating costs by more than half in the right temperatures.

For deeper efficiency rabbit holes, a nerd-level page like Energy Efficiency Hub pairs nicely with this math.

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3. Heating Performance Chart: How Output Changes with Temperature

Heat strips are boring in one sense: their heat output barely changes with outdoor temperature as long as the voltage stays stable. Heat pumps are more interesting: as outdoor air gets colder, there’s less heat for them to grab, and their output drops.

Here’s a simplified comparison for a 12,000 BTU class through-the-wall system with both a heat pump mode and an auxiliary heat strip:

What this chart tells Myth-Busting Jake:

• Above ~40°F, the heat pump is a clear efficiency champion and maintains most of its capacity.

• Around freezing, it’s still more efficient than strips, but the capacity decline becomes noticeable.

• Below mid-20s, it may struggle as a sole heat source, depending on the model.

• Heat strips don’t care; they deliver full output and full power draw in every temperature.

A chart like this isn’t brand-specific; it’s the general behavior of air-source heat pumps versus resistance heating. For brand and model curves, manufacturer data paired with technical summaries like Heat Pump Performance Charts are helpful.

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4. Which Climates Need Heat Pumps, Strips, or Both?

Let’s get practical. Myth-Busting Jake doesn’t care about theory if it doesn’t help you pick hardware.

4.1 Warm and Mild Winter Climates

Examples:

• Gulf Coast

• Deep South

• Coastal Southeast

• Parts of the Southwest

Typical winter lows: 30–45°F, rare dips below freezing.

Best option:

• Heat pump through-the-wall AC as primary heat.

• Maybe a small portable or baseboard heater for the rare cold snap.

Why: your heat pump stays efficient and near full capacity all winter. You’d be burning money using strips as a primary heat source here.

4.2 Moderate Winter Climates

Examples:

• Mid-Atlantic

• Inland Southeast

• Lower Midwest

• Some West Coast inland regions

Typical winter lows: 20–35°F, extended periods near freezing.

Best option:

• Heat pump through-the-wall AC with backup strips.

The heat pump handles the bulk of the heating when it’s 30–45°F outside. When temps drop into the 20s and the unit can’t keep up, the heat strip kicks in as auxiliary heat, not primary.

This is the sweet spot combo: heat pump for efficiency, strip for backup power. It keeps comfort high and costs under control.

4.3 Cold Winter Climates

Examples:

• Upper Midwest

• Northeast interior

• Mountain regions

Typical winter lows: 0–25°F, significant time below freezing, with brutal cold snaps.

Best option:

• Heat pump plus a serious backup heat source, or

• Electric strips as supplemental to a primary furnace, boiler, or other system.

In these climates, through-the-wall heat pumps can still save you significant money during milder shoulder seasons, but they shouldn’t be your only heat source. Strips are your guaranteed backup when the heat pump’s output tanks.

4.4 Very Mild or Shoulder Seasons Anywhere

If your “winter” is more like a chilly autumn, a heat pump mode on your wall unit is incredibly efficient. Running strips in those conditions is like heating your house with a hair dryer because you enjoy donating money to the utility.

For more climate-zone breakdowns, a zoning map or DOE-style regional chart at Climate Zone Map is handy to cross-reference with this advice.

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5. Cost Difference: Heat Pump vs Heat Strips in Real Dollars

Let’s walk through concrete cost examples, because this is where myths die fast.

Assumptions:

• You have a 12,000 BTU class unit.

• You need about 10,000 BTU/hour of heating on a typical winter day.

• Electricity costs $0.17 per kWh.

• You run heating 6 hours per day, 120 days per year.

5.1 Cost Using Only Electric Heat Strips

We already calculated the power draw required:

• 10,000 BTU/hour ≈ 2.93 kW of heat.

• With COP = 1.0, you pull 2.93 kW electric.

Cost per hour:

• 2.93 kW × $0.17 ≈ $0.50 per hour.

Daily cost:

• 6 × 0.50 = $3.00 per day.

Seasonal cost:

• 120 × 3.00 = $360 per season.

5.2 Cost Using Heat Pump as Primary, Strips Rarely

Let’s assume average COP over the season is 2.0 (reasonable for a moderate climate):

• Required electric input = 2.93 ÷ 2.01.47 kW.

Cost per hour:

• 1.47 × 0.17 ≈ $0.25 per hour.

Daily cost:

• 6 × 0.25 = $1.50 al giorno.

Seasonal cost:

• 120 × 1.50 = $180 per season.

Savings vs strip-only: about $180 every heating season.

If you use strips maybe 10–20 percent of the time on the coldest nights, you still save well over a hundred dollars per year relative to running strips all the time.

If you want to cross-check this kind of math with general heating cost comparison tools, a calculator page like Heating Cost Calculator is a good sandbox.

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6. What About “Heat Pumps Don’t Work in the Cold”?

This is one of my favorite myths to smash. Heat pumps absolutely do work in the cold; they just become less efficient and may not output enough heat to meet the load without help.

Facts Jake stands by:

• At 40–50°F, through-the-wall heat pumps are rock stars.

• Around freezing, they’re still more efficient than strips, but capacity decline becomes noticeable.

• Below about 20–25°F for most standard models, they often need help.

• That “help” can be electric strips inside the same unit, or a separate heat source.

The mistake people make is assuming “heat pumps are useless below freezing,” so they never buy the feature, then complain about high bills from running strips all winter.

Reality: If your winter ever spends meaningful time between 30–45°F, a heat pump can pay for itself. The colder part of the season doesn’t erase the savings from the milder part.

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7. When to Choose a Heat Strip-Only Through-the-Wall Unit

There are situations where Myth-Busting Jake will actually nod and say, “Yeah, strip-only makes sense.”

• You live in a building where the wall unit is backup only, and your main heating is gas or hydronic.

• The wall unit will be used rarely, maybe a few hours a week.

• You’re in a climate that is cold enough that the heat pump mode would rarely run efficiently anyway.

• Your electric rate is surprisingly low, and your usage is light.

In those cases, the simplicity and lower upfront cost of a strip-only wall unit might beat the complexity and extra cost of a heat pump model.

But if that unit is your main heat source for a room that sees daily winter use, strip-only is basically choosing the permanent high-bill option.

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8. When to Choose a Heat Pump + Strip Combo

This is my favorite configuration for most real-world users:

• Heat pump as primary heat whenever outdoor temps are above its low-ambient rating.

• Strip as backup or auxiliary when temps drop so low that the pump alone can’t keep up.

This gives you:

• Lowest possible operating cost across mild and moderate days.

• Guaranteed comfort on the coldest nights.

• Built-in redundancy if one function malfunctions temporarily.

For a combined strategy that makes sense across many climates, a planning guide like Hybrid Heating Guide fits well with this section.

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10. Upfront Cost vs Operating Cost

One of the loudest myths I hear is, “Heat pump models cost more, so I’ll save money with the cheaper strip-only unit.” That logic ignores the one number that actually matters: lifetime energy cost.

Suppose you’re choosing between two through-the-wall units:

• Model H (Heat Pump + Strip): $1,050

• Model S (Strip Only): $800

Price difference: $250.

From the earlier examples, using a heat pump as primary heat instead of strips can easily save around $180 per heating season in a moderate climate. That means Model H can effectively pay back its entire $250 premium in about a season and a half. After that, it puts money in your pocket every winter you run it.

If you barely ever use the built-in heat—say it’s a guest room that’s rarely occupied—then sure, the cheaper strip-only unit might win. But if this unit is going to heat a bedroom, office, or living space for several hours a day all winter, choosing solely on sticker price is classic false economy. Myth-Busting Jake rule: look at the entire ten-year picture, not the ten-minute decision.

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11. Quick Buying Checklist from Myth-Busting Jake

When you’re comparing through-the-wall ACs with different heating options, run through this simple checklist:

1. Climate: Do you spend many winter hours between 30–45°F? If yes, a heat pump is a huge win.

2. Usage: Is this the primary heat for that room, or a rare backup? Primary heat almost always justifies a heat pump.

3. Specs: Can you find actual heating BTU ratings at different outdoor temperatures, plus whether backup heat is a strip? If not, be suspicious.

4. Math: Take five minutes to estimate hours of use, cost per hour with heat pump vs strips, and multiply by your local kWh rate.

5. Backup: In colder climates, plan for backup heat even if you choose a heat pump model—built-in strips or a separate source.

You don’t need a PhD. You just need honesty about your climate, how often you’ll run the unit, and what your power company charges.

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12. Final Word from Myth-Busting Jake

Here’s the core truth I want you to walk away with: a heat pump moves heat; a strip makes heat. Moving is almost always cheaper than making. The moment you stop buying myths like “strips are stronger” and start buying based on COP, runtime, and cost per hour, your heating decisions get very easy.

Next time someone tells you heat pumps “don’t work” in winter, ask them what temperature they mean, how many hours they actually spend below that, and what their kWh rate is. Nine times out of ten, the numbers will show that a through-the-wall heat pump—especially paired with backup strips—is the smarter, cheaper choice for real homes and real winters.

That’s how Myth-Busting Jake thinks about heating options, and that’s how you keep comfort high while keeping your electric bill in its place.

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13. Mini FAQ: Fast Myths, Fast Answers

Q: Will a heat pump blow “cold air” compared to strips?
A: The discharge temperature from a heat pump is usually cooler than from red-hot strips, but it runs longer and more efficiently. The room still reaches the same setpoint; your bill is just lower getting there.

Q: If my climate hits 10°F sometimes, is a heat pump pointless?
A: No. If you spend dozens or hundreds of hours each winter between 30–45°F, those are prime heat pump hours. Use the pump whenever it can keep up, and let strips or another system cover the true deep-freeze days.

Q: Are strips more “reliable” because they’re simpler?
A: Strips are simple, yes—but they’re also simple money burners. A quality heat pump plus strip backup gives you both reliability and efficiency instead of forcing a choice between them.

 

In the next blog, you will learn about Maintenance Checklist: How to Keep a 12k Through-the-Wall AC Running Like New