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Will My Furnace Work When the Power Is Out?

Steve Hansen
/
August 25, 2023

Extreme weather has become more common in the last couple of decades, and that has resulted in more power outages. When electric power goes out for days and even weeks at a time, we all have to consider how we’ll keep our homes warm and cool, even if the lights are out. Let’s start with what happens to common heating systems.

Gas Furnace

If your home has a gas furnace, you might reasonably expect that it will work normally during a power outage. It uses natural gas or propane for heating, after all, so why would it need electricity to heat your home?

The short answer is that your furnace needs electricity for several components that must work together to deliver hot air around your home. Your thermostat is an electrical device, and when it senses that the temperature has dropped too low, it sends a signal to the furnace to fire up.

At the furnace, the igniter is an electrical device that makes a spark to ignite the gas. Modern furnaces do not have pilot lights, which are a tiny flame that keeps the furnace ready to deliver heat. Pilot lights are both wasteful and somewhat dangerous, so igniters have replaced them. The igniter receives the signal from the thermostat, activates and creates a spark that ignites the gas, and then the heat production starts.

Your furnace also has an electric blower, or fan, that distributes the hot air through the ducts around the house. Without the blower working, your furnace is nonfunctional.

What about other heating options? Are they any better at keeping your home warm during a power outage? For the most part, no.

Gas Boiler

Gas boilers are used for radiant heating systems that send hot water out to radiators or through heating tubes under the floor. A gas boiler is similar to a gas furnace in the way your system still needs a thermostat that activates an igniter to get combustion started. And instead of an electric blower distributing heat, this system uses an electric pump to circulate water through the system. All those components are electric and so won’t be functional during an outage.

Heat Pump

A heat pump is basically an air conditioner that can work in reverse to both heat and cool your home. It uses a refrigerant, which is a chemical compound that changes easily from a gas to a liquid to pull heat from the surrounding air, either inside or outside your home. A heat pump requires electricity to do that, so it will not operate during an outage.

Air Conditioner/Cooling

Power-outage warnings also apply to your cooling system. Whether you have a central air conditioning system, window air conditioners, evaporative coolers, or fans, all those devices depend on electric power, and living without them is miserable and even dangerous.

So What’s the Solution?

Your best solution is to make your home minimally vulnerable to outages. That would include making it extremely energy efficient by improving air sealing of doors and windows and maximizing the insulation so that the heating and cooling demand is lower. You would also build in some redundancy of critical systems such as electric power, and also have another way to provide heating and cooling.

Backup Power System

Adding a backup power system will give you the capability to power your electric functions as well as your heating and cooling systems, depending on the system you install. When you consider a backup power system, you will be faced with numerous options. If you own a single-family home, you can add a whole-house generator, a portable generator, a battery backup system, or a portable battery backup system. If you live in a multi-family building, a portable battery backup system may be your only option, but that can still be a major help in an outage.

This article offers a more comprehensive overview of backup power systems, but here’s a quick overview.

  • Whole-house generators: these usually run on natural gas, propane, or diesel fuel. To run everything in an average home, you’ll need a 20 kW or larger generator, which will cost you $5000 and up. Installation will cost another $5000 plus the transfer switch, which automatically activates the generator in the event of an outage.
  • Portable generators: these smaller units usually run on gasoline or diesel and will cost from $1000 to $4000. You’ll want to have an electrician advise you on how to connect this to your electric system.
  • Battery backup systems: this is the all-electric version of the whole-house generator. You’ll spend $10,000–$20,000 plus installation, but the Inflation Reduction Act offers incentives.
  • Portable battery backup systems: these small batteries offer great functionality but can’t power anything that requires a lot of electricity. Still, you can get a model like this one that will power your lights and other low-draw devices.

Heating

Backup heating will come in a few options: a wood stove, a pellet stove, or a space heater. If you can install a wood stove, you’ll be covered during a power outage. They’re more work and more mess than other types of heating systems, but definitely better than enduring a freezing home.

Pellet stoves are a bit different. Nearly all require electricity for an auger to feed the pellets from the hopper into the firebox. This one, however, uses a gravity-feed system to send the pellets into the fire. It’s a very odd-looking contraption too. This pellet stove has a battery backup built in, and says it offers 40 hours of runtime during an outage.

Space heaters also come in a few varieties. You’ll see kerosene heaters on offer, but those are banned in California due to their production of carbon monoxide. If you use one, you should only use it with a window slightly open to allow fresh air to enter and it should not be used overnight.

Propane heaters are safer than kerosene and this one just requires a gas line but no electricity to run. If you don’t have a gas line you’ll need a propane tank and hose. You’ll see many different brands, but they’re all similar, and they are designed to be wall mounted or set on the floor. This type of heater comes in several sizes to heat rooms of varying sizes, so you might want to choose which room(s) you heat. For a low price point you can ensure that you will have heat during an outage. You should still keep a window open, however, to ensure adequate fresh air. And you must have a working carbon monoxide detector in the room where the heater is located.

If you want a nicer appearance than the standard propane space heater, here’s a heater with the look of a wood stove. In addition, it will run on either propane or natural gas.

Another option is a catalytic heater. These cost a bit more but produce heat from a catalytic reaction, and they produce no flame. That makes them safer than a propane space heater, and they produce no carbon monoxide.

Finally for heating, you can consider a camping or utility heater like this one. This is a very flexible option, which you can just keep packed away until you need it. Keep in mind that buying small 1 lb. propane cylinders will end up being expensive if you need to use it for many hours per day over several days. You can also connect to a larger propane tank, which will end up being cheaper to run and you won’t have to change out the tanks as often.

Cooling

Power outages also happen in the warm months when we count on our air conditioning systems. Like our furnaces, those demand a lot of electricity to run. But unlike heating, we don’t have many options that easily replace our air conditioning.

One option is this portable unit from EcoFlow. You can’t replace your central air conditioning with this device, but if you’re faced with rolling blackouts during a heatwave, this may be the solution. Ecoflow says it will operate for eight hours on eco mode, so it seems like you could cool one room to reasonable comfort while your power is off. As it’s really designed as a small, portable system, one room will be all it can handle.

In addition, you can now take advantage of battery-powered and rechargeable fans. Just having air blowing directly on your skin is one of the best ways to help you stay cool.

You never know when extreme weather will knock your electricity out, or for how long, but you can prepare. And the next time an outage occurs, you may find yourself doing just fine.

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