How To Make Generator Quiet

Generators can be a great backup power source or a convenient way to bring electricity to a remote location, construction site, camping site, etc. However, they can also be quite loud, which can be a problem if you need to use one in a residential area or if you just want to reduce the noise level in your backyard.

There are several ways to make the generator quiet, and the best approach will depend on the specific power generator model and, of course, the budget.

Published: December 29, 2022.

 

Quick Intro to Power Generators

Power generators convert chemical energy stored in the fuel (gasoline, natural gas (NG), propane (LPG), diesel) into electricity via internal combustion engines - fuel is used to create mini-explosions which move the piston up and down, which make the crankshaft rotate, which in the end spins the electric generator.

The biggest noise source are the hot gases created in the cylinders which exit the power generators via mufflers - no matter how good the muffler is, these gases will create some noise.

However, one also has to take a few other details into account, including:

Enclosed or Open-Frame Generator

Fully enclosed power generators are in the form of a box, with just a muffler exhaust on one side and a control panel with receptacles on the other side. In order to access the inner parts, one has to remove the side panels, which increase the weight of the unit.

However, fully enclosed power generators are much quieter than open-frame power generators, which are basically metal frames with attached parts, including engines, generators, fuel tanks, control electronics, etc.

Most power generators up to 3-5kW are enclosed generators, while larger units are mostly open-frame units.

Inverter Generator vs. Non-Inverter Generator

Non-inverter power generators feature relatively simple electronics used to smooth out output voltage - their voltage frequency depends on the engine speed, which must spin at a designated speed regardless of the generator load.

Inverter power generators feature more complex control electronics, providing output power with much lower THD (Total Harmonic Distortions) since the form and frequency of output voltage don't depend on the engine speed, which can be variable - when the load on the generator is low, the engine can be throttled down, reducing fuel consumption and - noise!

Output Power

Noise levels depend on the generator load, and many manufacturers provide information about the noise levels, usually measured at 25% and 50% load, some 21-23 feet away.

The quietest power generators create 50 or less dB, @25% load, measured some 21-23 feet away.

Note: manufacturers don't provide information about the generator's orientation, but one can assume that the muffler was turned away from the measuring device.

How To Quiet Power Generator

There are several methods for making power generators quiet, but one must never forget that exhaust fumes contain dangerous Carbon Monoxide (CO) and that power generators require a constant flow of air to make the engine run and to cool down the engine and control electronics.

Note: some of the suggested methods are not supported by the generator manufacturers, and some can make you even lose a warranty...

Use A Soundproof Enclosure

One of the most effective ways to reduce generator noise is to enclose it in a soundproof box, enclosure, or at least a tent. Such enclosures are designed to absorb and deflect sound waves, which can significantly reduce the amount of noise that escapes from the generator.

There are a few different types of soundproof enclosures available, including:

• Pre-made enclosures: These are boxes, enclosures, or even tents that are specifically designed to fit around your generator. They're typically made from materials like foam or sound-absorbing panels and can be relatively easy to install. Pre-made enclosures are mostly safe for use, ensuring good airflow around the power generator. Most of the pre-made noise-reducing solutions also protect the power generators from rain, at least light rain.
• DIY enclosures: If you're handy and don't mind getting a little creative, you can also build your own soundproof enclosure. This can be a more budget-friendly option, but it will require some time and effort. You'll need to choose the right materials and design an enclosure that fits your generator and your needs.

Use Sound-Absorbing Materials

If you don't want to go through the hassle of building or buying a soundproof enclosure, you can still reduce generator noise by adding sound-absorbing materials to your existing setup. This could be as simple as hanging a piece of foam or a sound-absorbing panel near the generator.

You could also try using materials like sand or gravel to absorb sound waves. Simply fill several buckets with these materials and place them near the generator, especially near the exhaust - as the noise waves exit the muffler, they break down on uneven surfaces losing their strength. This won't provide as much soundproofing as a dedicated enclosure, but it can still make a noticeable difference.

Note: This is very similar to placing the power generator behind the tree when camping - the noise (sound waves) coming from the generator will hit the tree and reflect (bounce) in every possible direction, with the least sound waves being reflected toward the user. And if there are some bushes around, the noise will be reduced significantly.

Personally, get a few acoustic panels and place them around your power generator, making sure that the engine has plenty of air for operation and cooling and that acoustic panels don't make Carbon Monoxide buildups.

Use A Larger And Better Muffler

Another option for reducing generator noise is to install a new and larger muffler.

Power generators come with mufflers optimized in terms of size, weight, noise reduction, and similar.

These devices are designed to reduce the amount of noise that escapes from the exhaust pipe of your generator. They have a series of chambers or tubes that allow the exhaust gases to expand and cool before they're released into the air.

There are a few different types of mufflers available, and the best one for your generator will depend on its size and power output, so before buying a new muffler, do the homework and find which one is the best for your power generator in terms of noise reduction. Also, check its size (can it actually fit your unit), weight (especially if you are carrying a power generator by hands), maintenance procedures, etc.

Mufflers can be found at local hardware stores or online shops.

Water Muffler

A water muffler is a very efficient improvised muffler that suppresses the noise very well - fill a large bucket or barrel with plenty of water, add a heat-resistant pipe to the muffler exhaust and place it in the water.

All the gases created by the generator will go through the water, decreasing their temperature and energy and reducing noise.

On the other hand, the water muffler creates additional pressure for engine gases, decreasing the engine efficiency and increasing the fuel consumption and load on the engine - not by much, since it is highly dependent on the power generator and the pipe depth, but nonetheless...

Move The Generator Farther Away

If you have the space, you can also try moving the generator farther away from any areas where people will be. This can be especially effective if you're using the generator in a residential area or if you have neighbors who might be bothered by the noise.

Remember that the farther you move the generator, the longer your extension cords will need to be. Make sure to use the appropriate gauge and type of extension cord to ensure that you don't exceed the capacity of the cords or the generator.

Again, most manufacturers measure noise levels at a distance of 21-23 feet (~6.4 - 7 meters), which helps reduce the noise, but also helps disperse Carbon Monoxide and other fumes away from the living quarters.

Note: be sure to point the muffler exhaust away from the residential premises. This will decrease the noise even further.

Use A Generator With A Lower Decibel Rating

Finally, if you are looking for a new power generator and noise is a concern, you might want to consider purchasing one with a lower decibel rating.

These generators are designed to be quieter than other models, and they're a good choice if you need to use the generator in a residential area or if you just want to reduce the overall noise level.

Keep in mind that generators with lower decibel ratings will typically be more expensive than other models. However, the investment may be worth it if you need one.

The following comparison chart lists some of the best low-noise power generators with their most important features and specifications:

As one can see, inverter power generators with fully enclosed construction and standard mufflers can be very quiet - not cricket quiet, but almost, especially at lower loads.

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Long Story Short: Pre-made power generator enclosures, boxes, or tents can significantly reduce the noise and provide the power generator with rain protection while still ensuring plenty of air for normal power generator operation.

Power generators are complex devices, and replacing a muffler can reduce the noise levels, but one also must be aware that such action can make the engine work harder. Or, it can even decrease the load on the engine, but it can increase the power generator dimensions and weight - you win some, you lose some ...

Note: always operate power generators outside, away from the windows and doors, to avoid the buildup of dangerous Carbon Monoxide and other fumes. And no, oped garage door is not outdoors ...