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The Generac QuietSource series™ 48 kw standby power generator (premium-grade) has been discontinued and is not available for purchase at this time.

Generac QuietSource Series™ 48 kW Standby Power Generator (Premium-Grade)

(Based on expert analysis, manufacturer ratings and customer reviews)
3.6 out of 53.6 out of 53.6 out of 53.6 out of 53.6 out of 5
5 Reviews
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Liquid Cooled Standby Generators
48 kW
Rated Watts
5.4L V-8
Need Help? Call Our Generator Experts.

Product Video Disclaimer: "PED is not responsible for any variances from the product in this video and the item you purchase. Please review all product specs prior to purchase."

Premium-Grade Standby Generator
High-quality, liquid-cooled standby generator
Designed for luxury homes and commercial buildings

Low-speed exercise mode for quieter weekly tests
Exercises at a quiet 63 decibels at 23 feet
Sound level comparable to an idling car

Automotive-Style Engine
Powerful Generac V8 engine
Operates at half the speed of other engines (1800 vs. 3600 RPM)
Runs at a quiet 68 decibels at 23 feet under load

Aluminum Enclosure
Corrosion-resistant material ideal for salty air conditions
Sound attenuated acoustically designed enclosure

Tri-Lingual Digital Nexus™ Controller
Two-Line LCD Display provides service & maintenance intervals

Automatic Shutdown
High coolant temp, low coolant, low oil pressure and overspeed

Transfer Switch (Sold Separately)

Fork Lift or Loading Dock is Required for Delivery

  Model Number:QT04854ANAX
 Manufacturer:Generac QuietSource
 Made in USA:Yes
 Brand:Generac 5.4L V-8
 Consumer Engine Warranty:2 Years
 Commercial Engine Warranty:2 Years
 Engine RPM:1800 RPM
 Low Oil Alert/Shutdown:Yes
Product Specs
 Voltage120/240 Single-Phase
 Frequency:60 Hertz
 Cooling SystemLiquid Cooled
 Fuel TypeLP/Natural Gas
 NG Power Capacity48,000 Watts
 LP Power Capacity48,000 Watts
 NG Consumption (50% Load)392 ft³/hr (BTU: 392,000 BTU/HR)
 NG Consumption (100% Load)756 ft³/hr (BTU: 756,000 BTU/HR)
 LP Consumption (50% Load)4.14 gallons/hr (BTU: 375,705 BTU/HR)
 LP Consumption (100% Load)7.96 gallons/hr (BTU: 722,370 BTU/HR)
 Rated Amps:200 Amps @ 240 Volts (Single Phase)
 Decibel Rating @ 7m:63 Test (68 Run) db(A)
 Mounting PadConcrete (Not Included)
 Transfer Switch:Automatic (Not Included)
 Battery:Not Included (525 CCA)
 UL ListedYes
 Weight:1516 Lbs.
(195.58 x 86.36 x 114.30 cm)
 Dimensions:77"L x 34"W x 45"H
 Consumer Warranty:2 Years
 Commercial Warranty:2 Years
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  6 Questions
Q: I am considering a 48kw Generac QuietSource natural gas generator for my home in Estero, Fl. What size natural gas line is required to run this model (QT04854ANAX)?

by Jeff King from Florida on March 16, 2014

A: Here are the fuel pipe requirements on the Generac QT04854ANAX which will also be listed within the installation guide included with the generator......

Natural Gas:

1 Inch: Cannot Use
1-1/4 Inch: Cannot Use
1-1/2 Inch: Max Distance 50 Feet
2 Inch: Max Distance 230 Feet

Liquid Propane Vapor:

1 Inch: Cannot Use
1-1/4 Inch: Max Distance 70 Feet
1-1/2 Inch: Max Distance 165 Feet
2 Inch: Max Distance 620 Feet

Add 2.5ft per any bend, tee or angle in the pipe to the overall distance.

Gas Pipe sizing is one of the most commonly made mistakes. A properly sized gas pipe is critical to the proper operation of the generator. The generator inlet size has no bearing on the proper gas pipe size.

by Mike, Product Expert

Q: Jim, If I purchased the QT04854ANAX Model. What more will I need to Purchase to make the Unit automatically come on and of during emergency use? I'm sure there are the hidden items that if you don't ask, you find out after purchasing it that you need to spend another $5,000 to $10,000 to get it up and running properly.
by Royce Parfait from Tennessee on May 11, 2013

A: The items required to properly connect to your electrical system would be the Automatic Transfer Switch where the size is based on either the incoming utility amperage or the amperage of the electrical panel you are powering with the generator.

Generac Transfer Switches

You will also need the 12VDC starting battery so the unit can start when power fails. We do not sell the batteries for the larger generators so you will need to purchase that locally.

by Mike, Product Expert

Q: I'm going to build a house in the spring of 2013 and I want to have a standby generator installed when the house is built.

What would be the best size generator? I plan on having a geothermal heating/ac system and the house will be all electric.

by Dan from Kansas on August 06, 2012

A: Thank you for visiting Electric Generators Direct. In regards to your question, the generator size is determined by the starting amperage load of the equipment you are planning on powering when you lose power.

The starting amperage load will be much larger than the running load and proper calculations need to be done to properly size a unit.

We recommend having a certified electrician do your wattage calculations as every home is different.

The electrician would calculate with the following formula to properly size the generator which should be sized at 80% of its running capacity to allow enough flexibility to handle large intermittent loads and still keep voltage output at proper levels.

(Starting Amps x Volts = Watts)

Note: Geo-Thermal systems can require a tremendous amount of starting current and all calculations should be done onsite professionally.

by Mike, Product Expert

Q: How much lp gas will this unit use in 1 hour? what is the life expectancy of the generator and the v8 engine. I plan to run the unit with a startup at 6:00A.M. and shut down at 10:00 P.M.
by Ed Jones from Nevada on June 08, 2012

A: This model uses 4.1gal/hr when operating at half load and the full load runtime can be found in the specs available on the site under the specs link.

These units are designed for emergency backup power only and cannot be used as a primary power source.

The manufacturer does not provide a specific life span as this does depend on maintenance and care of the unit.

by Mike, Product Expert

Q: Hi Jim, I would like to bring the conduit up through the concrete pad under the generator. Where can I find the measurements for the exact place to be under the generator electrical wiring area ?
Thank you

by FRank from Connecticut on April 17, 2012

A: The installation drawing can be found in the specification sheet listed on the generator product page under the specs link. I have also added the individual installation drawing in the same section.

Installation Drawing

by Mike, Product Expert

Q: I'm looking for 45Kw generator that I would like to install indoors and run the exhaust pipe out through the wall. Per local fire department I can install up to a 240 gal tank, but I see no mention of storage tank size (recommended or otherwise). Please advise
by Alon from California on March 14, 2012

A: Please note that per the generator Installation Manual:
This equipment is a liquid-cooled, engine-driven generator set. The generator is designed to supply electrical power that operates critical electrical loads during utility power failure. The unit has been factory-installed in a weather resistant, all metal enclosure and is intended for outdoor installation only.
by Mike, Product Expert

Generac QuietSource QT04854ANAX Reviews & Ratings
Write Review
Overall Rating
3.6 out of 53.6 out of 53.6 out of 53.6 out of 53.6 out of 5
Quiet (2)
Fast (1)
I'd Buy It Again (1)
Price (1)
Features (1)
Durability (1)
Unreliable (1)
Low Quality (1)
Heavy (1)
50% of respondents would recommend this product to a friend
5 Reviews  Sort by 
Charles A.
Newport, WA
Purchased from Electric Generators Direct
Purchased 4/20/15
Most Helpful Positive Review
5 out of 55 out of 55 out of 55 out of 55 out of 5
Generac 48kw
I have it installed now. The installation went well. It starts and carries the load as I expected it to. I am pleased.
Charles Recommends This Generac QuietSource Product
Manufacturer Response
Brand Rep
We are happy to know that your installation went well and that the unit is providing ample power! If you haven't done so already, please be sure to register your unit with Generac Nation by providing the information required via the following link: . Doing so will allow you to initiate your product's warranty coverage and receive future consumer alerts. If you have any questions about the registration process, please do not hesitate to contact us directly at 888-GENERAC (436-3722).
Was this review helpful?
Patrick J.
Flosom, LA
Purchased from Electric Generators Direct
Purchased 4/16/15
Most Helpful Critical Review
1 out of 51 out of 51 out of 51 out of 51 out of 5
Won't Even Start
Totally upset that after spending $17-K, my new home backup system has yet to produce the first KW.

The local repairman now has to order a new starter.

Totally not happy with my purchase.
Patrick Does Not Recommend This Product
Mike, the Generator Expert
Product Expert
Sorry to hear that you are having problems with your generator.

This is the first we have heard that you have had issues and are hear to help get these problems resolved. Generac does have a great warranty on this generator and also a very large service network and by calling them direct at 888-436-3722 will get the unit up and running as quick as possible.
Manufacturer Response
Brand Rep
We are sorry to learn of the issues that you are currently experiencing with your automatic standby generator. Please know that any applicable warranty coverage can be provided by an independent authorized service provider in your local area. Moreover, if you would like to speak with us directly regarding your unit's current issues, please do not hesitate to contact us at 888-GENERAC (436-3722). We apologize for any frustration that this unfortunate scenario may have caused.
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Garfield, AR
Total Helpful Votes
222 Helpful Votes
5 out of 55 out of 55 out of 55 out of 55 out of 5
Almost Maintenence Free
I installed this 48 KW gen in 2010, along with a 400 AMP ATS. I've never had any trouble with either. I use a dedicated 500 gal LP tank and have had no fuel delivery problems even as low as 18 degrees F. Of course I placed the tank as close to the generator as allowed by local code. The control and annunciation system have been flawless in operation. The first 2 years the system didn't get much use other than the weekly automatic exercise program (1300 rpm).

It is located about 50 feet from... more
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Montz, LA
Purchased from Electric Generators Direct
Purchased 6/14/14
Total Helpful Votes
21 Helpful Votes
5 out of 55 out of 55 out of 55 out of 55 out of 5
A Big Job - But Worth It
I won't go into why I decided to purchase this beast - but I sure am glad I did. I got a great deal from EGD. These big generators are hard to move around - requiring special equipment - so most people will need help and good planning just to get it delivered.

I learned some lessons during this experience. I had a little trouble getting a solid quote for install but once I found a competent installer, I was set. The generator works perfectly (so far) and runs my entire house with ease. A... more
Pros: Features, Quiet, Price, I'd Buy It Again
Cons: Heavy
Thomas Recommends This Generac QuietSource Product
Was this review helpful?
Total Helpful Votes
25 Helpful Votes
2 out of 52 out of 52 out of 52 out of 52 out of 5
Still Not Working - Hurricane Coming
We bought this system and had it installed in our new house in September. It worked during the installation tests and weekly runs through the winter, but this Spring and into the Summer we have had repeated failures. The first time the factory-trained master electrician came to troubleshoot, he got on the phone with the factory and ordered a part. Now three weeks later, they came to install the part and the system still doesn't work. New (different) part now on order. Hurricane bearing... more
Pros: Quiet, Fast
Cons: Low Quality, Unreliable, Durability
Jim Does Not Recommend This Product
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Shop for the Generac QuietSource Series™ 48 kW Standby Power Generator (Premium-Grade) at Electric Generators Direct. Research Generac QuietSource 696471613308 standby liquid-cooled generators online. Find Generac QuietSource QT04854ANAX standby liquid-cooled generators & generac 48 kilowatt generac premium grade generator features and specifications.