can you run a space heater off a generator

Can you run a Space Heater off a Generator?

You want to run a space heater off a generator? Here’s everything you need to know about powering space heaters with generators and what you need to consider to stay safe!

Additionally, we’ll cover whether it makes sense to use generators to power space heaters and I’ll show you some handy alternatives (that might work even better for your purposes).

But first, let’s take a look at the generators.

Question: Can you run a space heater off a generator?

Answer: Yes, you can run a space heater off a generator. Most space heaters need 1500W of power. To stay safe, you should use a 2000W generator. Otherwise, you risk blowing fuses. Generally, running a space heater off a generator is energy inefficient though. We’ll cover what to do later on.

But first, let’s take a look at space heaters and generators.

What size generator do you need to run a space heater?

As already said in the quick answer, you can run space heaters safely using generators that deliver 2000W of power or more.

By having this 500W safety-buffer, you make sure that fluctuations in power don’t blow your fuse. Fluctuations could be caused by using an extension cord or changing the temperature settings on your heater’s thermostat.

A 2000W generator generally has no problem running a 1500W space heater.

But that’s all it can handle!

If you want to use more devices with your generator, you should lower the heater settings to 750W or use a bigger generator.

Most generators can’t handle a space heater and a fridge at the same time, for example when you’re in an RV. For such purposes, you need extra big generators.

Therefore, you should first check what exactly you need to power with your generator.

  • Do you only want to power a space heater? – 2000W are enough
  • Do you need to run an entire living room or RV on one generator? – You should get bigger gear in the 5000W area.

Here’s a video that shows what happens when you run a 1500W space heater off an 800W generator.

A generator can never supply more than the wattage it declares. You can see that the voltage drops when the 1500 watts heating mode is activated. Most likely the heater will not work properly.

Therefore, make sure you use a decent generator to run your space heater.

Recommended Generator for running a space heater

In case you don’t have a generator at home yet, here’s one we recommend that can easily run a space heater:

Why this one? With 2000W power, it can handle all common 1500W space heaters, even the big oil-filled radiators. It actually is a clone of a Yamaha generator, however, it performs just the same for less than half the price. You can actually tell by the ratings on amazon.

Will a 1000 watt generator run a space heater?

Yes, a 1000 watt generator will only run space heaters up to 750 watts. Most space heaters run on 1500W but have a lower power 750W setting. You can use this low-power setting. However, with 750W you will not be able to heat big rooms, and you might only raise the temperature by a few degrees. 

In general, use 1000W generators with space heaters only if you have no other choice. 

Safety tips for running a space heater off a generator

“NEVER use portable generators indoors or in garages, basements or sheds – even if doors and windows are open. They should always be used outside, a good distance from windows, doors, vents or any other opening.”

Bonneville Power Administration

If you need to run your space heater indoors, I recommend placing your generator either in a well-ventilated room and powering your space heater from there. Or use an extension cord to run the generator outdoors while using your heater indoors.

Use a thick, high-quality extension cord with your heater. Poor quality ones oftentimes caused fire accidents. Generally, you should never use an extension cord with a space heater when you plug it into your house power supply that is rated at 1500W. But running it with a 2000W generator is a little safer.

However, never heat in your absence! Generators and heaters are both potentially dangerous devices. So, always use them when you’re there. Just to get rid of the little off-chance that something happens.

Use a generator with 2000W or more. Never settle for less! Only the 2000W generators can safely handle space heaters. The more power your generator has, the smaller the chance of a fire or a blowing fuse gets.

Start the generator before plugging in your space heater. Most space heaters have power settings, so when you plug yours in, increase the power one at a time until you arrive at 1500W. If your space heater has no settings, just skip this step.

for safety: run space heater with generator outdoors
Image by Gavin St. Ours

Alternatives to space heaters in a power outage

Now you’re ready to power a space heater with a generator – but hold on! We’re not finished yet.

Most 2000W generators only last for about 3-5 hours on full power (and space heaters require full power). Even if we reduce the space heater’s power to only 750W (low heat), most generators will only last for 6-8 hours. That’s not very durable. 

But why?

Running a space heater off a generator is pretty inefficient. You lose power multiple times:

  1. You lose power when converting fuel to electricity.
  2. And you lose power when converting electricity to heat.

From a practical thinker’s perspective, this doesn’t make sense at all. Why don’t we just skip the electricity part and convert fuel to heat directly? This would increase the efficiency a lot. And it’s possible as well.

Here is how you can apply “direct heating”: Heating without using electricity.

Common methods for fuel heating are furnaces or gas heaters. But we’ll focus on propane heaters now.

Propane heaters are generally safe to run indoors. They don’t require any electricity and are way more efficient and inexpensive than using a generator to power an electric space heater.

Recommended indoor propane heater

This heater is a much much better choice than first getting a generator and then powering a space heater with it.

Here’s what a reviewer says who tested the heater with a 20lb propane tank:

“Seems to last forever. The heater will run 1+ week in snow/ice weather if I’m careful and willing to layer up a bit indoors.”

Generator Reviewer

But remember: Even with an indoor propane heater you should play safe and air your room regularly. For additional safety, you can also install a carbon monoxide alarm in your house that will notify you when there’s too much CO in the air.

Where powering a space heater with a generator actually makes sense

Powering a space heater with a generator could make sense in the following case.

Warming pets’ room – When you’re warming a pets’ room (keep the generator outdoors!) space heaters (especially oil-filled radiators are a safer choice than propane heaters. They don’t get too hot to the touch and are less hazardous. Space heaters also have automatic shut off and other safety features.

I’ve already reviewed space heaters for birds. Take a look at that if you’re interested!

Conclusion – Running a space heater off a generator

Yes, running a space heater off a generator is possible. 2000W (or above) generators are suited for handling the power a space heater requires.
Still, a generator that powers a space heater is not the most efficient way to do it.

Instead, you should look out for propane heaters (like the one we recommended). In most cases, the propane heater beats the space heater plus generator combo.

If you are curious about more home heating guides here’s our recommended next read: Infrared vs. Radiant Heaters: Are they the same?

You’ll learn quite some stuff about how these heaters work and in which cases you can use them!

Attributions: title image by this flickr user

About the Author

Daniel Hirsch

Daniel is an electrical engineer, blogger, and author. He studied electrical engineering and information technology and decided to blog about heaters after working in the temperature sensing industry.