The noise that portable generators produce can vary widely based on design. Those design configurations range from open engine framing to well insulated enclosures. So this tip is about generator noise control or how to reduce noise.
Two Generator Noise Sources
Generally speaking noise (sound level measured in decibels dB) is generated in two ways which are exhaust noise and mechanical engine noise.
The decibel level is directly related to the engine’s size, noise blocking for both the material type and placement, as well as the muffler type and size. Quiet generators will have dB levels below 60 while most open configurations will be at 70 dB or above. What this means is that at 70 dB you will be hearing something close to highway noise levels. While at the lower 60 dB plus or minus you can easily carry on a conversation in a normal talking voice.
Exhaust Noise Reduction
The first and most obvious noise source is the exhaust of the engine, without a muffler this can be very loud, think of that Harley Motorcycle that you hear going done the road.
With a good muffler/spark arrestor, this noise can be reduced significantly. The baffling on a muffler reduces the noise and therefore the more (larger) the muffler then the smaller the decibel output. Most new generators come with an good to excellent muffler to reduce this part of the noise picture.
Abating Mechanical Noise Sources
The second noise producer of mechanical noise of the engine and other mechanical parts is often overlooked by manufactures. The reasons can deal with the need for better cooling or be as just as simple as keeping the cost to a minimum.
The methods for reducing the noise are pretty straight forward. At the manufacturing end you can enclose the machine with various panels to reduce noise. A straight metal panel will provide some reduction as it takes the direct noise path and blocks it. However, as it as a potential to resonate with the noise it can and does still transfer a good portion of the sound through to the listener.
To abate noise further the manufacturer may use other materials that significantly reduce the sound transfer. In addition they can add insulation which is a great sound dissipater. This is the method used by the leaders in quiet generators, Yamaha and Honda.
Options to Further Quiet Any Generator
The further you can remove a noise source from your personal location the quieter your surrounding space. However, this can be impractical due to limitations in your accessible space or even in your need to add significant power cords to care your power. (read more here about Power Cord Sizing)
Another option may be to build your own sound barrier to provide for generator noise control and reduce sound output directly. One thing is that you don’t want to put it in an unventilated shed as there are other health hazards as well as fire hazards that exist.
Your Own Sound Deadening Enclosure
Building a container around your generator to reduce sound is actually an easy DIY project.
There are two things you have to consider when you do this. The first is space, which accounts for ventilation for the generator for the needed cooling. And second the area where you will run the generator.
In general the manufactures indicate that you need 3 or 4 feet clear of the generator to allow for safety for exhaust and cooling requirements. Therefore your first calculation should consider the width and length of the generator as well as the clearance to the edge of the enclosure. Keep in mind that air flow may be in only one direction so you may have some ability to tighten up your space on the sides.
In some cases you may be able to leave one or possibly two direction open that are away from where the folks would hear it. (Keep your good neighbor hat on here).
In other cases you may want to be able to fully enclosure and secure your generator. In this case you may get more elaborate with your enclosure by adding ventilation holes which are not direct line of sight. An example would be using a cutout in the main panel which is then covered by another inner or outside panel allowing indirect airflow, but blocking direct sound flow. Judicious placement of sound tile will deaden reflected sound.
Simplified Generator Sound Enclosure Ideas
Layout your needed clearances. Obtain enough plywood or press-board OSB to cover your perimeter (sides you want covered). If you want better protection you can put a roof on it which will also decrease noise further.
using some square posts or 2x4s for corners you’ll be able to nail or screw the pieces together. Do account for an easy access on one side to get your machine in and out. Probably a hinged panel with a latch/lock would work well.
The wood will work well for good noise damping, but to reduce noise bounce (the process of should reflection) you can add acoustic materials on the inside. This could easily be acoustic ceiling tiles, batt insulation, or the foam egg crate pads used as mattress and camping. These materials will absorb sound and are especially effective if you are considering offset vents.
Top Coverage and Weather Proofing
Covering the top of the generator helps in keeping weather off of the machine. You’ll want to consider a couple of things. You will want an opening or good draft flow for the exhaust. So depending on where your unit exhaust is located you will need to make sure that there is plenty of ventilation.
Also if you need to refuel you’ll like want to hinge the roof to make for easy access to the tank. And don’t forget to consider your access to the control panel.
With a little consideration you can quiet down that noise source to a dull noise in the background with a little thought and a labor.
In most cases you’re probably not overly concerned about noise for short duration or out on the job site where it’s just part of the process. At home you may be more concerned about portable generator noise control for longer term and want to have an enclosure to keep the peace in your household as well as the neighborhood. A self built container maybe the best way to do it.
Here’s a challenge for those of us that don’t like noise at all. Optimize an enclosure for weight as well as the assembly/dis-assembly functionality for quick setup, portability, and storage. Thinking plastic panels, foam, quick connect hinges.
Here’s some products I found to help you further your options:
FatMat 50 Sq Ft x 50 mil Thick Self-Adhesive No Logo FatMat Sound Deadener Bulk Pack w/Install Kit Using this on a fiberglass panel or wood could be a space saver option.