How many watts a heat pump needs, why start-up surge matters, how to size a generator, and the honest limits of portable power stations.
- Check both the outdoor and indoor unit labels, and any electric heat strip.
- Most portable power stations cannot run a ducted or 240 volt system.
- A transfer switch and sized generator is the usual whole-home route.
Heat pumps are common across Canada and the United States, including cold-climate models designed for harsh winters. They are efficient, but they still need electricity, so a power outage shuts them down. Backing one up is possible, though it takes more planning than most people expect.
This guide covers how to find your heat pump's wattage, how to size a generator, and why portable power stations have real limits here.
Find the real numbers for your system
Heat pump power draw varies widely with size, type and outdoor temperature. A small ductless mini-split uses far less than a ducted whole-home system. Look for the nameplate on the outdoor unit and the indoor unit or air handler. You will see voltage, running amps and sometimes a minimum circuit ampacity. Multiply amps by volts for a rough watt figure.
Remember that the system has more than one part. The outdoor compressor and fan, the indoor blower, and in many ducted systems a backup electric heat strip. That strip can be a very large load, and it is often the part that makes backup power difficult. Your installer or the manual can tell you what circuits are involved.
Running watts and start-up surge
Compressors need a burst of extra power when they start. Some heat pumps use variable-speed inverter compressors that start gently, which reduces the surge. Others use a standard compressor with a big start spike. Read the manual or ask the installer. We explain the concept in running watts vs starting watts.
Can a portable power station run one?
Small ductless mini-splits that plug into a standard outlet or run on 120 volts are the best candidates. Even then, heating a space uses a lot of energy over hours, so runtime is limited. Large ducted systems, systems with electric heat strips, and anything wired to 240 volts are generally beyond what a portable unit can supply.
- Check that the station's continuous output and surge rating exceed your unit's figures.
- Check the voltage. Many mini-splits need 240 volts and cannot connect to a 120 volt output.
- Compare watt-hours with realistic daily use using how to calculate watt hours.
- Do not connect a heat pump to a power station by modifying wiring yourself. Hardwired equipment needs a licensed electrician.
Sizing a generator for a heat pump
Add the running watts of the heat pump components, add the start-up surge of the largest motor, then add whatever else you want running, such as the fridge and lights. Our guide what size generator do I need walks through that. Connect through a transfer switch installed by a licensed electrician rather than back-feeding the house, which is dangerous. See transfer switch vs extension cords.
Run generators outdoors only, far from doors, windows and vents, and install battery powered carbon monoxide alarms. Read how to use a portable generator safely before you buy.
Cold weather performance
Heat pumps lose capacity as outdoor temperatures fall, and many switch to backup heat in extreme cold. That backup heat is where electricity use jumps. If your system relies on it, assume a larger load in the coldest weather. Cold also reduces battery performance, as covered in portable power station in cold weather.
A realistic backup plan
- Look up your heat pump's electrical specs and write them down.
- Decide whether you want to heat the whole home or one room.
- For one room, a small plug-in heating option or insulation and layers may be safer and cheaper. See how to stay warm without power.
- For the whole home, talk to an electrician about a transfer switch and generator inlet.
- Keep a non-electric plan, such as warm clothing and sleeping bags, regardless.
Quick answers
Can a power station run a mini-split heat pump?
Possibly a small 120 volt unit for limited hours. Check continuous output, surge rating and voltage against the label.
Does a heat pump need a lot of power to start?
It depends. Variable-speed compressors start gently, while standard compressors have a larger surge. Check the manual.
Can I plug a heat pump into a generator myself?
Only through proper equipment installed by a licensed electrician. Never back-feed a house through an outlet.