In this section
- GuideWindow heat pumpsHow window heat pumps differ from window ACs with heat strips, how Gradient and Midea's saddle units work, and what they can heat in cold weather.
- GuideDIY mini-splitsHow DIY mini-split heat pumps with pre-charged line sets work, which parts of the job you can do, and which need an electrician or a permit.
Why heat pumps cut bills
Electric resistance heat, from baseboards or a space heater, turns one unit of electricity into one unit of heat. A heat pump uses electricity to move heat from outdoors to indoors, and delivers two to four units of heat for each one it uses. The Department of Energy says heat pumps can cut electricity use for heating by about 50% compared with electric furnaces and baseboard heaters.
One room at a time, no ducts
- Window heat pumps sit in a window like an AC and plug into a standard outlet. Saddle designs, like Gradient’s and Midea’s, let the window still open. Good for renters and apartments. Window heat pumps.
- DIY mini-splits mount an indoor head on the wall and a compressor outside, connected through a small hole. Pre-charged line sets mean no refrigerant handling. Permanent, quieter and more powerful. DIY mini-splits.
- Window ACs with a heat mode are common and cheap, but many “heat” with a resistance coil, not a heat pump. Check the spec sheet for “heat pump”.
Size the unit to the room: our room size calculator uses ENERGY STAR’s chart.
The refrigerant change
New home AC and heat pump equipment is moving from R-410A to lower-impact refrigerants such as R-454B and R-32 under EPA rules. That’s why current MRCOOL DIY systems use R-454B line sets. It doesn’t affect equipment you already own, but parts for the two aren’t interchangeable.
Incentives
The federal 25C credit for heat pumps ended after 2025. Some utilities pay rebates for heat pumps, and a few states’ HEAR programs still cover them. What’s left in 2026.
Picks
Links marked “Paid link” go to Amazon. As an Amazon Associate we earn from qualifying purchases, at no cost to you. We don’t show prices because they change hourly.
Midea inverter window AC with heat pump
One room, cooling and shoulder-season heat
- Inverter compressor
- Heat pump mode, not just a resistance heater
- Plugs into a standard outlet (8,000 BTU size)
Cheaper than a mini-split and it moves to your next apartment with you.
Watch for: Heating output drops as it gets colder. Check the rated heating range before relying on it in winter.
MRCOOL DIY 5th Gen mini-split
Homeowners who want a permanent ductless heat pump
- Pre-charged R-454B line sets with quick connectors
- Single- and multi-zone versions
The only mainstream mini-split designed for owner installation; no vacuum pump or gauges needed.
Watch for: The outdoor unit needs a 240 V circuit for larger sizes. Wiring is a job for an electrician.
Gradient All-Weather 120V window heat pump
Cold-climate window heat pump
- Saddles the sill, so the window still opens
- Standard 120 V outlet
- ENERGY STAR certified
Built for winter heating as well as cooling, which most window units aren't.
Watch for: Sold by Gradient, not on Amazon. Expensive compared with a window AC.