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Model # 6244
MSRP: $4,589.00
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About Generac.com

Who is Generac?

Since 1959, Generac Power Systems has been designing and manufacturing backup power generators for residential, commercial and industrial applications. They have grown to be the world's largest provider of residential standby generators. Generac generators has revolutionized the commercial market with the first cost effective product line meeting the needs of small and mid-sized businesses.


Avg. Product Review Rating: 5.0/5 (based on 45 reviews - read reviews) Write a Review - $10 Store Credit

Generac Guardian 20kW Standby Generator Pre Packaged 200 Amp Service Rated ATS 6244

  • True Power Electrical Technology
  • Two Line LCD Multi-Lingual Digital Evolution Controller
  • Includes 200 Amp Service Rated ATS with Digital Power Management technology (DPM) NEMA 3R Rated
  • Electronic Governor
  • External Main Circuit Breaker, System Status & Maintenance Interval LED Indicators
  • Sound Attenuated Enclosure
  • Flexible Fuel Line Connector
  • Composite Mounting Pad
  • Natural Gas or LP Gas Operation
  • 5 Year Limited Warranty
  • UL 2200 Listed


Details and Specifications

The Generac Guardian Series standby generators are designed to start and operate automatically during a power outage. The 20kW Generac 6244 package is a popular standby generator that uses the integrated Evolution Controller sold by Norwall Power Systems and includes a 20-kilowatt generator packaged with an 200 amp, service-entrance-rated automatic transfer switch.

Fuel choices

All Guardian generators operate on either natural gas or on LP gas. Availability and cost are the main factors in choosing between the two fuels, but the fuel choice also affects the power output of the generator. The 6244 can produce a continuous 20 kilowatts of power using LP gas, but that is reduced to 18 kilowatts for natural gas. Fuel consumption at fifty percent load runs about 2.0 gallons per hour for LP gas and 3.9 gallons per hour at full load. Natural gas use is 205 cubic feet per hour at half load, and 308 cubic feet per hour at full load. Required fuel pressure to generator fuel inlet at all load ranges 3.5" - 7" water column for natural gas or 10" - 12" water column for LP gas.


The engine is Generac's own overhead valve industrial engine; the only engine designed specifically for use in a generator. The design of the V-twin, 999 cc engine allows for extended operation with an extended maintenance cycle twice that of most generators. It runs cooler and smoother with less vibration and easily switches from natural gas to LP gas in the field.

The engine senses low oil levels and shuts itself down to prevent damage. Pressurized lubrication helps keep the engine operating smoothly and for extended periods without interruption.

Transfer Switch

The Generac Automatic Transfer Switch is a UL rated, automated transfer switch that handles the changeover from utility power to the standby generator in the event of a power outage and incorporates load management for high demand appliances. The switch is normally mounted close to the existing service panel for ease of access, installation and convenience.

The Automatic Transfer Switch incorporates load management for high demand appliances through a load-shedding controller and manages one or two air conditioners without additional equipment, and up to four additional high demand appliances with the addition of Power Management Modules(PMM).

Evolution Controller

The Evolution Controller is an integral component of all Guardian generators and manages generator functions. Once a week it starts the 6244 generator and exercises it for 12 minutes. When the generator is not in use, the controller monitors and charges the battery to ensure it is ready when needed and alerts the owner to replace the battery when it will no longer hold a charge.

When a power outage occurs, the controller senses the outage and waits to ensure it was not a momentary interruption, then starts the generator after 2-1500 seconds (programmable by an authorized Generac dealer, default start is 10 seconds). During operation, it monitors generator voltage continuously and adjusts it for utility quality power, and also controls the frequency to keep it at a steady 60 hertz. When utility power is restored, the controller instructs the transfer switch to change back to utility power, but continues to operate the generator in a cool-down mode for up to one minute before shutting it down.

The Evolution Controller also senses incorrect/improper wiring to alert the user and prevent damage to the system. If the any part of the system shuts down, it can notify the homeowner through a general alarm displayed on the generator control panel. The optional advanced wireless remote controller sounds an audible alarm if a malfunction is detected. The Mobile Link allows remote monitoring of generator status via web, email or texts.

Generator Unit

The alternator or generating unit is the heart of the system that produces electricity. It utilizes an efficient revolving magnetic field and a stationary armature with skewed stators that keep the current output smooth, clean, and free of spikes and noise. The unit employs automatic voltage regulation for continuous, unvarying power and also helps to provide for the momentary high inrush currents required by electric motors during startup.

Appearance and Noise

The overall appearance is clean and unobtrusive, with a smooth, protective case. Certified for 18” Installation to the home (3rd Party-certified to NFPA standards provided it is located away from doors, windows and fresh air intakes, and unless otherwise directed by local codes.) The entire unit stands 29 inches tall, 48 inches wide and 25 inches deep. The aluminum cabinet resists rust and is covered by epoxy paint for a long lasting finish. The engine's muffler is located within the cabinet to guard against burns and injury and keeps the generator's noise level to 66db or lower. The 6244 package includes the fascia and trim kit normally sold as an accessory.

20kw Generator by Generac 6244 Includes:
200 Amp Service Rated Automatic Transfer Switch with Digital Power Management technology (DPM) Nema 3R Rated #RTSY200A3, Flexible Fuel Line Connector, Composite Mounting Pad, Base Fascia

USA Engineered & Built

Product Videos

What is a Generac Automatic Home Standby Generator (01:47)
When the power goes out even if its just for a few hours life is disrupted
  • What is a Gene...
    When the power goes out even if its just for a few hours life ...

Warranty Information

Manufactures Limited Warranty: 5 Years

Product Specifications

Model Number 6244
Manufacturer Generac Power Systems
Made In USA Yes
Rated Watts 20/18kW
Rated Amps 83.3 LP/75 NG
Voltage 120/240V Single Phase
A/C Ton Rating 5 Ton
Enclosure Aluminum
UL Listed Yes
Decibel Rating 66 db(A)
Starting System Automatic
Low Oil Alert Yes
Hour Meter Yes
Battery Requirement Group 26R, 12V, 525 CCA
Mounting Pad Composite Base Attached
Product Weight 451 lbs.
Shipping Weight 550 lbs.
Dimensions (Inches) 48L x 25W x 29H
Engine Brand Generac OHVI V-Twin
Engine Size 999 cc
Engine RPM 3600
Cast Iron Sleeve Yes
Cooling System Air Cooled
Alternator Type Brushed
Frequency 60 Hz
Auto Voltage Regulation Yes
Fuel Type LP/NG
NG Power Capacity 18kW
LP Power Capacity 20kW
NG Consumption @ Full Load 308 cu.ft/hr
NG Consumption @ 1/2 Load 205 cu.ft/hr
LP Consumption @ Full Load 3.9 gal/hr
LP Consumption @ 1/2 Load 2.0 gal/hr
Transfer Switch
Transfer Switch Model RTSY200A3
Transfer Switch Amps 200 Amps
Transfer Switch Circuits Service Rated - Whole House
ATS Poles 2
Warranty Information
Consumer Warranty 5 Year Limited
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Product Reviews

Previous | Showing reviews 21-30 of 45 | Next

  1. Win! Win! Hands Down.

    Posted by F. E. C. on 28th Dec 2013

    I've ordered Generac from others but their customer service cannot compare to Norwall. Keep up the great work and common sense!

  2. Best money we spent when we built our out in the middle of nowhere ranching operation!

    Posted by Elizabeth Brownlee on 14th Dec 2013

    If you are looking for peace of mind when the weather turns bad, this is the generator for you. This generator is so quiet, I often forget it is there until the electricity blinks, and it kicks in with plenty of power. Perfect unit for our ranching operation in the Texas Panhandle. It is easy to service and gives us that backup power that is needed during bad weather emergencies.

    Delivery was prompt and helpful.

    We are ordering this same generator for our New Mexico operation as well.

    I have recommended both Generac and Norwall to several other operators and friends in this area. A great product and a fantastic supplier all in one purchase.

    You will not be sorry with this purchase!

    Thanks for a great product....Elizabeth

  3. Very Pleased With My Purchase!

    Posted by Phyllis V. on 8th Dec 2013

    I have had this generator for over a year now and it has been very dependable. My rural power comes from an electric co-op and the outages are unpredictable. It is hooked up to my propane tank nearby. It always preforms when I do experience outages. I highly recommend owning one.

  4. Great Product and easy to set up

    Posted by Kirk M. on 1st Dec 2013

    As a builder in the Oklahoma area I have a number of customers who request standby generators to keep power on after severe storms that are common to our area. We've been using this unit exclusively for over two years and have never had an issue. They are easy to install and this package is a great value compared to what I can get this for locally, and the shipping is always super fast from Norwall, so we are able to ship directly to the job at the completion of the home. If you are a builder the one thing I would recommend is buying a transfer switch up front and then ordering the package and take that transfer switch out for the next house. This way you can install the transfer switch at Electric installation post frame and then wait to deliver the unit at or near the job completion so the unit isn't sitting there during construction. We actually keep two transfer switches in rotation this way as it's soooo much cheaper to buy this package over the transfer switch and generator separately.

  5. Reliable Standby Power for a Reasonable Price

    Posted by Brian Librino on 20th Nov 2013

    I am an electrical contractor who has installed 100's of generators over the past few years. It is my opinion that Generac makes an excellent product that combines excellent features for a good consumer value. I get asked all the time what is better, and my response is, Generac has been a consistently reliable product for me to offer my customers. I have to stand behind the product I provide and if I had a lot of problems I would certainly look to other manufacturers. Generac provides a good network of support for the equipment they sell. Other's tend to isolate their products from being serviced by other than a select few and make parts availability even more difficult. All things considered Generac is a good product for the contractor and the end user.

  6. Great product and quality for the price

    Posted by William Mihal for W & P Enterprises on 19th Nov 2013

    I have installed Generac standby generators in the past and finally decided to install one for myself. I am very satisfied with the quality and price for this unit the 20 KW and 200 Amp transfer switch. The unit offers reliability and product support at the top of the chain compared to some of the other manufacturers. I would recommend these units to everyone.

  7. Had ours over a year and a half.........OUTSTANDING!

    Posted by Nancy on 14th Nov 2013

    The best purchase we have ever made. We have had numerous power outages due to storms, broken power poles from accidents on the highway... etc. It has functioned with absolute reliability. Runs our whole home, the 220 well pump, and our barn. We live in a very rural area, and repairs can be a long time coming, and with this we can have heat, AC, television, internet, and go right on with living and taking care of our horses and all the things one takes for granted when the power is on.... You will LOVE this unit.

  8. Invest In The Best

    Posted by Mike on 4th Nov 2013

    Trouble-free standby power. I recommend Generac Guardian series and Norwall to all my clients and friend. Two great companies to deal wit..Generac stands behind the product and Norwall gets it to you fast and at a great price.

  9. Good Product, Great Service

    Posted by Michael Somers on 3rd Nov 2013

    This is the generator to get if you want whole home protection. It is bundled with the proper service rated transfer switch. Fast shipping - ordered on Sunday night and was delivered by Thursday afternoon. UPS Freight delivery was very friendly and called the day before to set up a delivery time window. Delivery driver used pallet jack to put into our garage and waited for us to unpack it to make sure nothing was damaged and everything was there. Moving the generator to it's installation place was not easy. You will need several strong people and/or heavy/special equipment as this weighs over 450 pounds. I would strongly recommend having a qualified and experienced electrician help with the electrical hookup, preferably one who has installed one before. It took 2 people (my self and the electrician) a good 4-5 hours to do all of the electrical hook up. Another major factor to consider is making sure you have the proper amount of gas flow. You will most likely need to upgrade your piping or install a new line to a generator of this size. See the Generac sizing guide for more information. The generator comes factory configured for natural gas. If you are going to convert it to LP, like we did, make sure you are pressing down on the orange knob and turning it in the right direction at the same time. Initially we tried just turning it and it would not budge, after a call to Generac support the conversion was easy after learning that we needed to push down at the same time as turning. Both Generac and Norwall support were very helpful and promptly answered my questions. Came with a free Mobile Link and $100 Home Depot gift card. I would also recommend the cold weather kit (Norwall also sells these) if the generator will be installed in a climate where temps regularly fall below 32F.

  10. Generac Generator 20kW

    Posted by Tadeuz on 2nd Nov 2013

    Best ever product!!! Works quietly. Great customer service, which gave great explanations. For sure we are going to recommend to anybody! Thank you Norwall.

Previous | Showing reviews 21-30 of 45 | Next

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Shipping Terms

All generators include 24 hour delivery notification and residential delivery. Liftgate service is available on all air-cooled generators and some liquid cooled units – Please call for verification. Free Shipping is curbside service only. Curbside service means the freight company will deliver to your address and lower your generator to the ground. The freight company will not back down driveways, place a generator in a building or where it is being installed. You are responsible for arranging the movement and setting of the generator.

Some restrictions apply to "Free Shipping" you may either view our
Shipping Information page or contact us for details.