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Heat pumps are taking the world by storm right now, because they do the seemingly impossible: produce 3x more heat per watt than any other type of heater. Seriously: a modern gas furnace is 95% efficient in converting energy to heat. An electric resistance space heater is 100% efficient. A heat pump? 300% efficient.

There's a reason heat pump rebates are one of the key policies in the recent Inflation Reduction Act: they're one of the few "silver bullet" technologies we have readily available today.

How do they work?

The core technology actually isn't new: it's how your refrigerator or AC works today. Your fridge or AC doesn't "create cold"—it extracts heat out of the inside air using refrigerants, and then blows it out.A heat pump set to heat mode is like turning a window AC unit around: instead of extracting heat from your house, it extracts heat from the outdoor air and blows it inside, while blowing now-colder air back outside.

Why not a central system?

If you're a homeowner, this is something to consider—especially if you qualify for rebates. But central heat pump systems are out of reach for most renters. Others may just want the simplicity of something portable and available to use in a couple days, without needing professional installation.

They do AC too

Oh, and by the way: all portable heat pumps with a heater function also can do AC (note: not all AC portable heat pumps can do heat. Look for "with heat" in the product title.) So you're getting a 2 for 1 deal. 🙌🏼

If you want to learn more, this is a great (but long) introduction to portable heat pumps:

So, which one should you get?

Avoid one-hose models

I have tried both a one-hose Black & Decker model and now a new 2-in-1 hose Cooper & Hunter model. I cannot recommend strongly enough: get a 2 hose or 2-in-1 hose model, especially one with an inverter.

One-hose models act like a fan placed in your window blowing out, creating negative pressure in the room and causing ambient air to get sucked in to replace the outgoing air. It significantly lowers efficiency. As an example, in a bedroom with the door closed, I ran the one-hose Black & Decker on heat mode for 3 hours and only managed to lift the temp from 52 to 56—well below the performance of my 1500w space heater.

The best portable heat pump for heating

The new Cooper & Hunter AC+heat model, CH-STLS-14AC, has a 2 in 1 hose, variable inverter, and 8.9 CEER efficiency rating (vs. 5.9 for other dual hose models). It was $607 on Amazon using a coupon, or available for $600 direct from the manufacturer.

This C&H model has been amazing—it heats our living room, dining room, bathroom, and kitchen. It's much quieter than the Black & Decker, and cycles on and off less (thanks to the variable inverter).

The wifi is also great to have. I schedule it to turn on before we wake up or get home. Plus, it's compatible with Google Home and Alexa, so it's easy to turn on or off without being near it.

Finally, the window kit + two types of insulating foam are much higher quality than the Black & Decker. I was able to form a nice seal in my sliding window. They even included insulation for the window hose.

Combined with small space heaters in our bedrooms, I've been able to completely avoid turning on our old inefficient gas furnace entirely this winter in SF—more than paying for the cost of the heat pump.

Alternative budget pick

I also considered dual-hose models from the brand NewAir, which were quite affordable ($400 shipped after using a 25% off discount code I found online) and looked nice. Ultimately decided to spring for the inverter (for the increase in efficiency and reduction in noise) and a 2-in-1 hose (for the aesthetics).

Downsides to portable heat pumps as heaters

There are four main downsides of portable heat pumps to be aware of:

• Portable heat pumps are heavy (50-60lbs). They all come with wheels, but note it'll probably require two people to carry up stairs, unless you hit the gym frequently.
• When used in heat mode, you need a place to drain the condensate that forms.
• Unlike modern central heat pump systems, they typically don't heat if it's below freezing outside.
• They take up window space and the hoses aren't very chic.

#1 is not an issue once they're in your home.

#2 can be solved by placing it on a small 6-8" stand (or pile of books in my case) and putting the included small drain hose into a bucket, which you need to drain once every day or two. Or, you could buy a cheap piece of longer hose (and a $40 drain pump, if needed) and have it drip out your window for worry-free operation.

#3 can be solved by moving somewhere with warmer winters (jk). But sorry midwesterners and New Englanders, this might not work during your coldest days. It's worked for me into the high 30s, but lacks some of the defrosting features found on central systems.

#4 is a thing but you get used to it.