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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

Showing reviews 1-10 of 45 | Next

  1. Always Dependable

    Posted by Chuck M. on 4th Sep 2014

    I have purchased numerous units from Norwall.
    I have always been satisfied and happy with my purchases and service.

  2. Norwall Power Systems the Best!!!!!!

    Posted by Jim Camp on 15th Aug 2014

    Norwall Power Systems sold us a Generac 20kW home standby generator several months ago and we are well pleased. They helped us find a qualified electrician to install it for us.

    The unit is set up once a week to run for 12 minutes to keep it in top condition. We have used the unit once for 4 hours when the electricity was off.

    Norwall Power Systems is the best place to buy a home standby generator.

  3. Very satisfied with our Generac standby home generator from Norwall

    Posted by Jim Camp on 14th Aug 2014

    We had our 20KW Generac standby home generator installed several months ago and we are very satisfied with our unit. It runs once a week on a schedule of 12 minutes every Sunday.

    Electricity has gone off several times since we installed the generator, and each time it has cranked and run as designed. Most times electricity was off only a few minutes, but once it was off for 4 hours.

    We love the dependably of our Generac standby generator and the fact that there is nothing we need to do when we loose power or when the power is restored. We just sit back and the unit automatically turns on or off. THANKS!!!!

  4. Affordable & Easy

    Posted by Larry P on 11th Aug 2014

    Norwall has made it affordable and easy. I placed my order online using Pay Pal for payment it was fast and easy check out. Received my generator 9 days later by UPS freight and placed generator on awaiting slab same evening with help from my friend and his excavator. I am a licensed electrician so I installed my own 6244 generator, completed all connections gas / electrical lines and testing on Saturday. Lost utility power on Sunday and my Generac generator operated exactly as it should by providing hours of power. Well I am no stranger to Generac generators I have installed many in my area over the last few years. I will recommend anyone looking for generators and generator products to buy at Norwall. Thanks.

  5. Easy Ordering & Install

    Posted by Mike on 7th Aug 2014

    I just received my new Generac 20kW system and was very pleased with how easy it was to order from Norwall and it's everything they advertised. Thank You, I now have peace of mind while traveling away from home.

  6. Easy To Install

    Posted by Carmelo G. on 9th Jul 2014

    I've been using the Generac standby system for over 10 years now. I love everything it has to offer. Very user friendly and easy to install. Have not had one complaint over 10 years.

  7. Easy to Install and Quiet Unit

    Posted by Kevin on 10th Jun 2014

    Customer really liked the look of the unit, I liked how easy it was to install. The unit runs pretty quiet, you can still hear a faint rumble in the house but it's better than not having power.

  8. What An Easy Company To Do Business With!!!!!

    Posted by Happy Customer! on 30th May 2014

    I am very pleased with the Generac generator. Another south LA person getting ready for hurricane season. The warranty is outstanding and the quality of the generator and ATS is superior to all the rest!

  9. Excellent service by Norwall

    Posted by Wyndol on 17th Apr 2014

    I placed my order online, mailed Norwall a cashiers check in order to eliminate the 4 day hold period on personal checks. Immediate shipment by Norwall and prompt delivery by UPS Freight. I received my unit and had a Generac dealer contracted to install. Due to rain, he had a few days delay in pouring the slab. He returned today and did the install. My local propane dealer brought the tank and a tanker showed up and filled the tank. The installer cranked the unit and checked it out completely.

    The unit ran great with no problems. Thanks Norwall for a good job.

  10. No Worries

    Posted by Donna on 7th Apr 2014

    Peace of MIND and SAFETY are the two best words that describe this purchase. We lose power when it's sunny and dry - we don't need to wait for any bad weather. We've gone 8 days without power with 8 horses, 5 dogs, 2 cats,
    and 2 humans - ENOUGH! We also are lucky enough to lose our water (we have a well) Did you know how much water this group drinks. Not going to be COLD, THIRSTY or HUNGRY anymore. GREAT INVESTMENT!

Showing reviews 1-10 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.