Furnace or Space Heater? What’s Cheaper?

It’s not a surprise to anyone that Central Air Conditioning is expensive! But does that same logic apply to Central Heating? Would you save more money using a personal space heater than running your furnace to heat your whole home?

Heating Disclaimers

Let’s talk about a few caveats first.

How big is your house? If you have a 6 bedroom house but it’s only you and your spouse living at home, do you need to heat the whole home? Do you have multiple systems where you can leave one off and run only the occupied side?

Is your home well-insulated, or is it drafty? The heat retention of your home and the space you’re desiring to heat will play a big role in determining cost.

space heater

Cost of Space Heaters & Furnaces

Time to jump straight into the meat and potatoes. You want to know whether using a space heater will save you money.

The answer is yes and no.

From a pure energy to dollar ratio, electricity costs more than gas. If you make a habit of checking the unit price on groceries, your furnace will outperform a space heater in “price per unit” any day of the week.

The average residential electrical rate in San Diego at the time of writing is 16.35¢/kWh, while the average cost per therm is $1.75.

What does mean? We understand kilowatt hours, but therms are a bit more confusing. To help, you should know that 1 kWh = .03 therms. That means that there are between 29 and 30 kWhs in a single therm. For ease of use, take 30 kWhs and multiple by 16 cents.

That’s $4.80 of electricity for every $1.75 of natural gas in San Diego.

Pretty easy to see why using your furnace is the way to go, right?

But that’s not really how it works, nor is it the end of the story. There’s more that we need to consider.

When to Use a Space Heater

You only need to heat one space

If you have a big home, or even a regular sized home, but you’re by yourself, you may question whether or not heating your whole home is worth it.

Do you sit on the couch or arm chair all evening long? Would a tiny space heater be all that’s necessary for you?

Keep in mind that to make running a space heater more cost efficient, you need to turn the thermostat down. Way down. I don’t know exact numbers, but in the low fifties would be a solid guess.

That’s cold.

So when you leave that protected space be prepared to bundle up.

Warming a room without central heat.

Sometimes you want heat in a room where central heat doesn’t reach, like say you’re garage.

Then it’s a no-brainer to use the space heater, but keep in mind that your garage is likely not insulated. That means as soon as you turn the heater off, the heat will disperse in under 30 minutes.

All that energy used to heat the space is wasted, so use it sparingly, only when you need it most.

Types of Space Heaters

Fan Forced Heaters

This is your average variety space heater that you’ve likely passed on the Walmart shelf countless times.

These are great for immediate gratification, but they do a poor job at heating the whole room and they are major electricity hogs.

These little guys are really only useful for Me, Myself, and I. Be prepared to fight over the prime sitting spot if you have a large family.

They are perfect for cold mornings, though, when all you need a quick fix to get your body warmed up and start the day.

Radiant Heaters

Radiators, infrared, and convection heaters all use a form of radiant heat. This is where the unit progressively warms the air around it, rather than producing hot air.

These units take a lot more time to warm the space, but are the most cost effective (and quietest) way to heat a whole room. If you’re looking to warm a den or living space where the whole family can cozy up together, a radiant heater might be just what you need.

When to Use a Furnace

If none of the above scenarios fit you, then running your furnace might be the best option for you.

Are multiple rooms in your house occupied at once? Is dad in the den, mom in the kitchen, with children in their rooms and grandma in the sitting room?

It doesn’t make sense to run space heaters in so many places. Even if those occupied rooms still only cover half of your available space, a furnace is the way to go.

If your house is small, it’s entirely possible that running a furnace is still your best decision even if you’re the only one living there and you stay in a single space all evening.

furnace flames burner

That’s because heating your house little to do with how many rooms you have and more to do with where your thermostat is located.

Your furnace will turn off, not when the entire house has been heated, but when the temperature of the air around your thermostat reaches the set temperature.

Do you have two unused rooms that don’t need heating?

Closing the registers in those rooms will do nothing to save you money, and can in fact do the opposite as your furnace was designed to heat your whole house, and closing off rooms could affect the pressurization of the system.

Space Heater or Furnace? What’s right for you?

The empty-nester or ultimate penny-pincher will be able to save money running a space heater over a furnace, but they’ll have to sacrifice a lot to do it.

They’ll need to deal with freezing rooms in the rest of the house, slower heating in your desired living space, and the need to plug and unplug the heater when not in use.

Furnace users can still save money by following winter energy saving tips like lowering their thermostat 2-3 degrees below what you’re normally comfortable with. Given enough time, you’ll get used to it and the higher temperature will feel hot.

smart thermostat

Have Questions?

Still have questions about your furnace? If you’re in San Diego, give Precision Temperature a call. Whether you need a repair, installation estimate, or a simple maintenance, we’re here for you.

Give us a call at 619-588-5321 and one of our staff will be able to assist you.

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