One of the key features of a home generator — whether that’s for everyday use in the garage or yard, or as a standby generator to power your home — is how quiet the generator is when it’s running. But how quiet (or loud) are they?
Are Diesel Generators Loud?
Diesel generators run on internal combustion diesel engines. These engines use high compression and a glow plug to ignite the diesel fuel in the combustion chamber. The high combustion level causes intense low-frequency vibrations that travel through the motor and out the exhaust system, resulting in a distinct sound.
Diesel generators can be fairly loud for home use. This is one reason that they tend to be more popular for industrial, construction, mining, and agriculture use, rather than as home generators. When a diesel generator is run at higher RPM and output levels (e.g. 70% of max) to accommodate higher current draws it will be nearly twice as loud as when it’s running at low output levels (e.g. 25% of max).
If a diesel engine is not thoroughly muffled and surrounded by sound-deadening material or an enclosure, it can be quite loud. Running diesel generators at lower speeds tends to result in much quieter operation. And enclosing the generator in a heavy shed or concrete block room with sound deadening on the inside can further reduce the drone.
Diesel generator noise levels generally fall within these ranges:
- A 10-20 kW diesel generator will generally emit between 60-80 decibels from 23 feet (7 m) away. This is considered moderate to quiet and is equivalent to soft music or conversation level. 66 dB is comparable to the noise a central air conditioner unit makes.
- A 50 kW diesel generator normally emits about 85 decibels. This is as noisy as city traffic.
- 1500 kW diesel generator can emit 105 decibels. This is as loud as or louder than a jet engine.
Typical Noise Levels
To give you a sense of how loud generators are, the noise level inside the typical home is about 40 decibels. 60-70 decibels are equivalent to background music or regular conversation. Air conditioners at a distance of 23 feet (7m) make about 68 decibels, whereas washing machines make 70 decibels. A revving motorcycle engine is 95 decibels. 100 decibels is the typical maximum for headphones. Anything over 100 decibels like a jackhammer or explosion is extremely loud.
How many decibels is too loud?
Extended exposure to 70-plus decibels will lead to hearing decline. A generator outputting 85 dB will start to produce hearing impairment with 2 hours of exposure. If the generator is making 100 dB it only takes 15 minutes to cause hearing impairment.
If steps are not taken to reduce the noise of a loud diesel generator then you and your neighbors will likely be annoyed by the constant drone. If the generator is loud enough and the sound goes on for days it can lead to hearing damage.
What Is Considered Quiet for a Diesel Generator?
The quietest 10-20 kW whole home backup diesel generators will output decibel levels between 48 to 60 dB at 23 feet (7m) away.
Who makes the quietest 10-20 kW diesel generators?
To answer that question, here is a diesel generator decibel comparison chart for some of the quieter home standby diesel generators.
|Generator Make & Model||Kilowatts||Decibels|
|Multiquip DCA10SPXU4C||10 kW||61 dB|
|Kubota Lowboy II GL11000TM||10 kW||68 dB|
|Generac RD020||20 kW||65 dB|
|Generac MDG25IF4||20 kW||67 dB|
|Multiquip DCA20SPXU4F||20 kW||63 dB|
|Cummins CMHG 20000||20 kW||63 dB|
|Kohler 30REOZK4||24 kW||66 dB|
What is a good dB for a generator?
Generators that produce less than 50-60 decibels are considered quiet. Generators that produce 60-70 dB are quieter than average. 70-80 dB is a typical average noise for a diesel generator. Generators that are 80-90 decibels are considered louder than the average
Are Diesel Generators Quieter Than Gas Generators?
Old diesel engines were very loud. This made generators powered by diesel very intrusive, and significantly louder than gas generators.
However, modern diesel generators are balanced, muffled, and insulated to a much greater extent than models from pre-2000. Today, many home backup generators powered by diesel will be comparable noise-wise to equivalent kilowatt output gas generators. The only real difference tends to be at low idle speeds, where diesel engines vibrate more than gas engines and produce more noise.
This video should help understand the pros and cons of diesel backup generators for your home:
Frequently Asked Questions About Diesel Generator Noise
How can I make my whole house diesel generator quieter?
The generator should be placed on a soft surface. Quiet your generator using sound deflectors or replace the muffler with a quieter one. Build a muffle box or acoustic enclosure.
How loud is a Kohler diesel whole house generator?
The 24 kW Kohler 30REOZK4 diesel generator produces 66 dB. This is comparable to that of a central air conditioner.
Who makes the quietest diesel-powered home backup generator?
The 10 kW Multiquip DCA10SPXU4C noise level is only 61 dB. This is the lowest we’ve found for a diesel generator capable of running your whole home.
Generac’s larger 15 kW and 20 kW diesel generators are known as some of the quietest available. Their RD015 and RD020 diesel generators only put out 65 dB of sound in normal operation.
Are diesel generators worth it for home backup?
A diesel generator used for whole-home backup power has many advantages:
Diesel generators are typically more fuel-efficient than gas generators, particularly under heavy loads. Diesel engines last a long time and require minimal maintenance. They can endure extreme temperatures with the right oil. Diesel fuel is readily available, even in rural areas, and the motor can be converted to run on biofuel, kerosene, or frying oil with inexpensive kits. Diesel generators come in much larger sizes than gas or LNG / propane generators, so they can be sized to power a large house or an entire farm or industrial building if needed. Finally, diesel generators tend to be somewhat less expensive than gas generators.
If you can deal with the minor additional noise over a gas or LNG / propane generator and can locate it so the diesel fumes are away from where you breathe, then a diesel generator is definitely worth it for home backup.
Are diesel generators any good for home applications?
Several factors contribute to the success of diesel generators for whole-home backup power. Because diesel engines tend to be workhorses, this is the main reason. They are easier to maintain than a gas-powered generator. Durability-wise a quality diesel generator from a well-known brand like Generac, Kubota, Kohler, Multiquip, or Cummins will always be a smart purchase.
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