The best portable power stations for a gas furnace

Who this is for

You have a gas furnace, the power goes out in winter, and the house starts cooling the moment the blower stops. The furnace itself asks little: it burns its own fuel and needs the grid only for the blower motor and the control board. What you want is that much running through the night, indoors, without a generator to start in the snow.

If the heat in your house is electric rather than gas, this is not your plan; we sized a blower and its controls, not a heating element. If what you want is the fridge, the router and a few lamps, that is our page on portable power stations for home backup. And if you are not willing to have an electrician at the furnace, read the hooking-it-up section first, because nothing here reaches the blower without one.

How much battery you need

The blower is the plan. Everything here running at once takes 430 to 1,320 watts, and the blower is more than nine-tenths of the energy; the router, the modem and a few LED lamps together barely move the total. Starting the blower is the second number and a different one: 1,230 to 3,620 watts for a split second, and a station whose peak rating falls short of that does not run the furnace weakly, it fails to start it.

The range is that wide because two furnaces are not the same appliance. A variable-speed ECM blower sips and an older PSC motor gulps, and that gap alone is threefold. Then the weather sets the duty cycle: on a mild night the blower runs perhaps a third of the hour, and in a hard freeze better than two-thirds of it. Multiply the two together across 12 hours and you get the difference between 1,635 and 10,800 watt-hours. The furnace nameplate settles the first half of that, so read it before you buy anything.

We size on the harder end. Of the 58 units we track, 25 carry the easy end of the night and not one carries the hard end. So the shape of the advice is this: buy the peak rating that will start your own blower, expect a mild night to be covered and a bitter one not to be, and treat everything past that as a recharge problem rather than a bigger-box problem.

A gas furnace blower, Wi-Fi and a few LED lights for a 12-hour night, run against all 58 units we track: 25 clear at least the best case, 30 do not, and 3 could not be judged (a missing maker figure or an unresolved recall identity). Every figure is from the maker’s own page or manual; nothing here was tested by us. The method.

Day two and three

Twice that stretch, a full day (24 hours) of the same loads, needs 3,270 to 21,600 watt-hours. The EcoFlow DELTA Pro 3 is the only one of the three that covers even the bottom of it on a single charge, nothing we track covers the top, and past the first night the question stops being which box and becomes how you put energy back into it.

Winter is the worst season to ask that. The sun is low, the day is short and a snowed-over panel delivers nothing at all, so solar is the weakest refill exactly where this page needs it most. If the grid comes back in patches, a wall outlet settles the argument and all three take a useful top-up in the lull. If it stays down, buy the expansion battery before the second panel, because it works in the dark, or run a generator outside and let it refill the station indoors, which is the arrangement our generator page is about.

Hooking it up safely

A gas furnace has no plug. The blower and the control board come off a circuit in the breaker panel, which is why every pick here needs wiring work before it is any use. There are two ways to do it. The small one is a furnace transfer switch: an electrician fits a plug and a switch at the furnace itself, so the furnace can come off its house circuit, plug into the station, and go back afterwards. The larger one is a power inlet box wired to a transfer switch or an interlock at the panel, which buys you the furnace circuit and whatever else you chose. A transfer switch disconnects the house from the grid before it connects the station; an interlock is a plate on the panel that physically stops the main breaker and the backfed generator breaker being on at the same time. Reliance Controls says its inlet boxes must be fitted by a qualified electrician in compliance with local codes, and marks its generator-ready panel as not for do-it-yourself installation. Electricians on the trade forums frame the choice as cost against judgment: an interlock is cheaper and reaches any circuit within the station's output, while a transfer switch costs more and pre-selects a few circuits, so there is less to get wrong in the dark.

What you must not do is feed the house by plugging the station into a wall socket. Generac says backfed power can seriously injure or kill the line worker restoring your street, and that backfeeding is illegal in many places and against the National Electrical Code. EcoFlow, which makes two of our three picks, says the same thing in its own manual: do not hook a power station to a building's electrical system without a properly installed isolation switch. Code guidance on optional standby systems requires that switch so the utility and the station can never be live together; a permit is due the moment a transfer switch or interlock goes in, and most building departments expect a licensed electrician to sign the electrical subpermit. Get the quote before you buy the box. If it comes back as more wiring than you want, the same inlet takes a generator instead, which is our page on portable generators for home backup, though CPSC says a generator runs outdoors only, at least twenty feet from the house with the exhaust pointed away, and that is a harder rule to keep in a blizzard than it sounds.

Buying it right

A search for any of these models returns bundles, sibling models and, often, the same unit under two listings at different prices. We link only a listing whose own title states the bare unit and its exact battery and output; the box should say the same. Check the seller is the maker or Amazon itself, and that the model number on the label matches the one on this page.

EcoFlow DELTA 2 Max

• The listing we verified: “EF ECOFLOW Portable Power Station DELTA 2 Max 2048Wh, 2400W LiFePO4 Battery”, $1,049 when checked. Title states 2048Wh and 2400W, matching our record exactly.
• “EF ECOFLOW DELTA 2 Max Power Station Extra Battery, 2048Wh LiFePO4 Battery”, $879: the same unit under a second listing at $879; we link the cheaper verified one.
• “EF ECOFLOW DELTA 3 Max Portable Power Station, 2048Wh LFP Battery, 2400W”, $1,199: a different model that a search for this one returns.
• “EF EcoFlow Delta 2 Max Portable Power Station with 800W Alternator Charger”, $1,249: a bundle, not the bare unit; the extra hardware is in the price.
• “EF ECOFLOW DELTA 2 Max Portable Power Station, 2048Wh, 2400W”, $1,399: the same unit under a second listing at $1,399; we link the cheaper verified one.

Anker SOLIX F3800

• The listing we verified: “Anker SOLIX F3800 Portable Power Station, 3,840Wh”, $2,200 when checked. Title states 3840Wh and the exact model name with no variant word; it does not state a wattage, so output was not cross-checked against our 6000W record. (previously verified ASIN, re-checked by direct lookup)
• “Anker SOLIX F3800 Portable Power Station and 400W Solar Panel, 3,840Wh”, $2,400: a bundle, not the bare unit; the extra hardware is in the price.
• “Anker SOLIX F3800 Portable Power Station, 3840Wh, LiFePO4 Batteries, Ultra-High 6000W AC Output with 120V/240V, Solar Generator for Home Backup and Outdoor Camping (Renewed)”, $1,759: Listing is renewed/refurbished, not the new base unit..

EcoFlow DELTA Pro 3

• The listing we verified: “EF ECOFLOW DELTA Pro 3 Portable Power Station, 4096Wh, 4000W AC Output”, $3,699 when checked. Title states 4096Wh and 4000W, matching our record exactly.
• “EF ECOFLOW Power Station 4096Wh DELTA Pro 3 with 400W Portable Solar Panel”, $3,099: a bundle, not the bare unit; the extra hardware is in the price.
• “EF ECOFLOW Portable Power Station 3600Wh DELTA Pro, 120V 3600W AC Output”, $1,899: a different model that a search for this one returns.
• “EF ECOFLOW 12kWh Portable Power Station: DELTA Pro 3 with 2 Extra Batteries”, $6,169: Listing title does not state a capacity, so base-unit identity cannot be confirmed..

What this page can’t promise

This page sizes a battery against a blower it has never met. Whether yours is a variable-speed motor or an old single-speed one moves the answer more than any choice between the picks, and no battery helps a furnace that was never wired to accept one. We cannot promise your furnace will run, only tell you what it would take and what the wiring half involves.

Nothing here was tested by us. The figures are the makers' own, read off their pages and manuals and cited under each pick, and where a marketing page and a printed manual disagree we say so rather than take the better number. What owners report comes from hands-on review sites, labelled as such.

The competition

Every unit we track was run against the same plan. The ones that clear at least the best case are below with their own shortfall; the ones that do not are listed with the rule they fail.

Other plans we sized

• Home backupThe best portable power stations for home backup

  A fridge, the internet, a few lamps and everyone's phones through a day without the grid, indoors, with no engine to run. Sized on the harder end of every range.

• Camping and road tripsThe best portable power stations for camping

  Two nights of phones, a laptop and a few lights is a small job with a wide range, and the range is what catches people out. All three picks cover the easy end of it on one charge; the hard end takes a panel at the site or a full charge before you leave.

• CPAPPortable power for a CPAP machine: one night, and three

  A CPAP is a small, steady load, so this comes down to battery size and one switch: the heated humidifier. Covering a single night is settled; covering three, or running the heat, takes a bigger box.

• Portable generatorsThe best portable generators for home backup

  Three generators judged on the one number that decides the job: the watts on tap for the second a fridge and a chest freezer both restart at once. Not battery capacity, and not the running total.

• ComparedThe home-backup class: DELTA Pro 3, SOLIX F3800, Explorer 5000 Plus and the rest

  The largest portable power stations on one table, run against a full-day household plan, with expansion paths, 240V output and the makers' gaps marked.

• RefrigeratorHow much battery it takes to run a refrigerator, and which power station does it

  A fridge is the appliance everyone wants kept running, and the one whose appetite varies most from house to house. Size it on the harder end of that range and the choice of station mostly makes itself.

• Sump pumpThe best portable power stations for a sump pump

  A sump pump is a motor that starts hard and then runs in bursts: the starting surge decides which station can start it at all, and the weather decides how much energy it drinks. Sized on the harder end of every range.

• Well pumpThe best backup power for a well pump

  A well pump is the hardest start in an ordinary house, and it is wired in at 240 volts rather than plugged into anything. That is why this plan usually lands on a generator, and why every figure here is sized on the harder end of its range.

• ComparedAnker SOLIX F3800 vs F3800 Plus: the real differences

  The Anker SOLIX F3800 and F3800 Plus side by side from Anker's own figures, judged against one full-day household plan, with the real differences marked.

• Camping with a fridgeThe best portable power stations for camping with a fridge

  Put a compressor fridge in the back of the car and it becomes most of the battery: it is the one thing in your kit that keeps drawing while you sleep. We size this page from the hard end of every range.

• GuidePower station or generator: which do you actually need?

  This is the decision that comes before choosing a product, and it is the expensive one to get wrong in either direction. A battery bought for a well pump is wasted money; a standby generator bought to keep a router alive is a great deal more of it.

• GuideHow to connect a power station to your house

  These four methods differ less in how much power they move than in what they can reach: a cord reaches a plug, transfer equipment reaches a circuit. The fifth thing people try, a cord into a wall socket, can kill the line worker restoring your power.

• GuideSolar panels for a power station: how many, and how long

  Panels are where the optimism creeps into a backup plan. The arithmetic is simple enough to do on the back of an envelope, and the answer it gives you is the best case, not the likely one.

• GuideExpansion batteries: what an extra battery for a power station actually does

  An extra battery for a power station is the cheapest-sounding fix for the wrong problem about half the time. It buys hours, it does not buy watts, and the pack you buy has to be the exact one your station was built for.