Is It Safe to Use a Propane Heater Indoors?


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Last Updated: April 22, 2021

Propane heaters are an easy and affordable way to heat your home in emergencies but are they safe to use indoors?

Can You Use A Propane Heater Indoors?

Short answer: Yes it is safe to use a propane heater indoors, so long as you take precautions against fire and provide proper ventilation, most propane heaters are perfectly safe for indoor use.

What Do I Need To Be Aware Of?

Whilst propane heaters are safe when used properly you need to have a good understanding of basic safety precautions to keep you and your family safe.

Carbon Monoxide Poisoning

Carbon monoxide is an odorless, colorless gas that is released during the combustion process.  Even though today’s propane heaters burn very clean, they will still release some CO gas.

This is a serious issue: Many deaths occur during power outages due to CO poisoning, especially because of improper use of heaters.

Follow these guidelines to prevent CO poisoning when using propane heaters.

Only Use Propane Heaters Rated for Indoor Use

It is important you only use propane heaters rated for indoor use!

Studies like this one have shown propane heaters rated for outdoor use produce CO levels of 100ppm within at little as 50 minutes of use.  Exposure to these levels can result in sickness.

Levels of 150ppm can be deadly in just 8 hours (see chart here).

By contrast, indoor-rated propane heaters have automatic shutoffs which keep them from reaching these high levels.

Ventilate

You will need to leave a window cracked open while using a propane heater, even if it is rated for indoor use.

The ventilation requirements vary depending on the BTUs of the heater.

For example, the Mr. Heater Big Buddy requires 18 square inches of ventilation (4.25 x 4.25 inches).

Check the heater’s user manual to see how much ventilation is required.

Cracking a window might seem to defeat the purpose of a heater.  However, the heater will produce more heat than is lost through the window.

Even if it is very cold, always ventilate!

Look At the Flame Color

When the heater is burning the fuel efficiently, it will produce less CO gas.  The color of the flame will give you a clue to how cleanly the propane is being burned. (source)

  • Blue flames: This is what you want to see. The fuel is being burned cleanly with little CO gas being produced.
  • Red, orange or yellow flames: If you see these colors, it is a sign the propane is not being fully burnt and more CO gas is being produced.

Use a Battery Operated CO Detector

Good indoor propane heaters have built-in CO detector and shut off automatically if levels gets too high. However, CO poisoning is too serious to be trusted to built-in detectors.

I recommend also getting a battery-operated CO detector to use whenever you are operating your heater or other fuel-burning devices.

Fire Hazard

Any heater – including portable space heaters as well as gas heaters – poses a fire risk.  If they topple over, they can overheat and start a fire.

Likewise, if anything gets too close to the heating element, it can also catch on fire.

However good indoor propane heaters have features to make them safer.

The most important one against fire is an automatic tip-over shutoff; the heater will automatically shut off if it falls over.  Some heaters also have overheat detection and will shut off if they get too warm.

Regardless of how many safety features your propane heater has, you should always make sure there is at least 3 feet of space around it.  Keep it well away from any fire hazards like curtains and blankets.

If you have small children or pets, you will want to be extra careful.

Consider using duct tape to attach the heater’s base to a heavy platform to keep it from getting knocked over and never leave the heater unattended.

Oxygen Depletion

Propane heaters require oxygen to burn the fuel.  Over time, an indoor propane heater could use up too much oxygen in the space, resulting in dangerously low levels of oxygen.

This is a completely separate issue from CO poisoning.

Many indoor propane heaters have built-in oxygen depletion sensors (ODS) which will cause the heater to shut off if oxygen levels go below 18%.  This feature also protects against CO poisoning (source).

Even with automatic ODS shut-off, you still need to ventilate the space to provide oxygen.  It’s not worth the risk.

Note: Heaters with ODS will not work at high altitudes because of the lower oxygen levels there.  If you live somewhere above 4,000 feet, you may need a heater without the ODS safety feature.

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