Can You Run a Generator In Your Garage with The Door Open?

So it’s raining or snowing outside and you can’t take out your generator, but you want to power your equipment to complete an important task.

You will certainly contemplate running it from inside your garage.

See Also: Can You Use A Generator To Power A Mobile Home?

Accordingly, Can You Run a Generator in A Garage with The Door Open?

As a regular thing – No; once in a while when it’s very necessary – Yes. Even in must-do situations, you must address a few issues to remove the dangers. For instance, generators, just like any other machine that burns fossil fuels or wood, release considerable amounts of CO (Carbon Monoxide) in the air. CO can build up quickly in poorly ventilated spaces.

You don’t want to be exposed to carbon monoxide – it’s both colorless and odorless and can be poisonous if it gets in your respiratory system.

The fact that it’s odorless and colorless means you could be oblivious to exposure until it’s too late. A typical human needs just 50% CO concentration in the blood to die.

Later in the section, we’ll take a glance at ways to avoid CO poisoning.

But first, here’s why you should avoid running your generator in the garage even with an open door:

Four Reasons Not To Utilize A Generator In The Garage

1. Carbon Monoxide Poisoning

You shouldn’t run your generator in the garage for the same reason you wouldn’t leave your car engine running for hours in the same space.

The reason is Carbon Monoxide poisoning.

Generators are capable of producing as much CO as 450 cars.

As many as 70 people die of Carbon Monoxide poisoning every year in the United States alone.

2. Overheating Issues

In usual conditions, some parts of the generator set can get hotter than 700°F (371°C).

The air leaving the radiator can be as hot as 160°F (71°C).

If this air is allowed to recirculate in the garage, the room temperature will certainly exceed the ambient room temperature and overheat the garage.

Garages are seldom built with this problem in mind.

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Your garage door alone may not be large enough to permit maximum air exchange.

As such, poor ventilation will be a big issue in its own right even though it’s the main driving factor behind carbon monoxide poisoning and most other issues.

Note that overheating doesn’t merely make the garage unbearable for the user but may cause the generator to underperform in the long run.

3. Toxic and Potentially Flammable Fumes

Depending on the quality of the fuel and the state of your generator, you may have to deal with toxic diesel fumes and soot.

Because your garage is poorly ventilated, the irritating dirt will end up in your lungs. Immediate health effects are coughs, headache, lightheadedness, and nausea.

They are also known to set off pre-existing allergies such as asthma.

The user manual that came with the generator may have warmed you about the fire hazard posed by the fuel.

It’s generally recommended that you keep the tank closed to prevent a fire outbreak.

4. Noise Issues

Depending on the kind of task you’re working on in the garage, generator noises could be either distractive or intolerable, or both.

It’s equally bad for your health as it may reduce your hearing ability. The noise may upset the people in the next room as well if the garage shares a wall with the home.

How To Go About Operating A Generator In The Garage

Well then. So, let’s say you must run your generator in the garage, how do you go about it?

You can run a generator in your garage only if you improve ventilation to quickly expel smoke and Carbon Monoxide and keep temperatures within the acceptable range.

The following preventive measures don’t guarantee absolute safety but they are proven:

STEP 1: Point The Exhaust Towards the Open Door

As mentioned earlier, the main bottleneck to safety and comfort in this situation is poor ventilation.

If you must use your generator in the garage, consider pointing the exhaust toward the door to release the exhaust gases outside immediately after they are produced.

STEP 2: Install A Carbon Monoxide Detector

You have to have a Carbon Monoxide detector to be alerted immediately after the generator starts to release the toxic gas.

STEP 3: Temperature Control Measures

Most of the concerns arising from running a generator indoors can be addressed by boosting air movement through better ventilation.

Maximum air movement is necessary for two purposes:

  • Cooling the engine block and radiator (if your set has a mounted radiator, that is)
  • Removing the toxic fumes and Carbon Monoxide

Here are temporary temperature control measures:

Roof and Ceiling Fans

Whether you prefer ceiling or roof fans, having any type of fan in place can help improve air circulation.

However, you will use several more fans than you’d normally need.

That’s because you will be dealing with 2 issues:

  • sweltering temperatures
  • and Carbon Monoxide.


If you didn’t know, humid air traps heat to make the room feel a little hotter than it is.

If you plan to use your generator in the winter, then a dehumidifier can be a great way to reduce heat and soggy uncomfortable feeling.

Unlike fans, you don’t need several dehumidifiers to do the job – one powerful device is enough.

Remove The Clutter

A cluttered space is likely to get hotter faster than an organized garage because of the obstruction to air circulation.

Also, some surfaces such as those made from metal are good absorbers of heat and may keep it radiating around for longer.

If you plan to use your generator more often in the future, then it would be prudent that you settle for permanent cooling options, like these:

Air Conditioner, preferably a mini-split AC machine

Air conditioning is the surest and most permanent way to cool your garage.

These machines can reduce your indoor temperature by as much as 10 – 18° F (5 – 10° C).

The best thing is that you can adjust the thermostat to push the AC machine to achieve much lower temperatures.

However, there’s going to be a limit to how low you can go, often no lower than 50 degrees.

Add Attic Vents

More often than not, attic vents often accompany specific insulation.

Better yet, they can be used alone to increase ventilation. It’s perfectly OK, even encouraged, to accompany your attic vents with attic fans.

Keep Your Generator Smoke-Free

If your generator is prone to producing a lot of smoke, consider calling a specialist to investigate and correct the problem.

This won’t remove the need for fans, it just reduces the number of required fans.

Note that equipment intended to improve air circulation needs to be set up in such a way that lots of cold fresh air flow into the garage from above via entry vents to replace heavy hot polluted air leaving via bottom-placed exit vents.

Simple portable or ceiling fans are perfect in one-off situations or if you don’t intend to run the generator for hours.

In advanced situations with prolonged runtime, you will need to combine more than one of the above-suggested methods of ventilation and temperature control.


To summarize everything, you can’t run a generator in an enclosed garage (even with the open door) unless it’s very necessary, in which case you must improve ventilation and temperature control.