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Model # 6551
MSRP: $4,799.00
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Avg. Product Review Rating: 5.0/5 (based on 7 reviews - read reviews) Write a Review - $10 Store Credit

Generac Guardian 22kW Standby Generator NG/LP Single Phase Aluminum Pre Packaged with 200 Amp Service Rated ATS | 6551

  • True Power Electrical Technology
  • Two Line LCD Multilingual Digital
  • Electronic Governor
  • External Main Circuit Breaker, System Status & Maintenance Interval LED Indicators
  • 5 Minute, Weekly, Bi-Weekly or Monthly Exerciser
  • GFCI Duplex Outlet
  • Sound Attenuated Aluminum Enclosure
  • Includes Flexible Fuel Line Connector
  • Composite Mounting Pad - Attached
  • Natural Gas Or LP Operation
  • Capability to be installed within 18" of a building
  • 5 Year Limited Warranty


Generac Power Systems 6551 Details and Specifications

Generac Guardian 22kW Home Standby Generator NG/LP Single Phase Aluminum Pre Packaged with 200 Amp Service Entrance Rated Automatic Transfer Switch | 6551

The 22 kW Guardian® Series home standby generator is the largest air-cooled home standby generator on the market. Not only does it deliver all the features and functionality customers have come to expect from the market-leading brand of home standby generators, but with an MSRP that is the lowest cost per kilowatt of any air-cooled home standby generator. Provides whole house coverage for many homes.

Features & Benefits:

Lowest Cost Per Kilowatt:  Homeowners can invest in a home standby air-cooled generator size that used to only be available in much more expensive, liquid-cooled models, giving them the lowest cost per kilowatt available.

Generac OHVI® Engine:  Your Guardian Series generator might have to get you through days—or weeks—without utility power. Generac’s OHVI® engine, specifically designed for generator use, provides the reliability to power through the most severe outages.

True Power™ Technology:  Best-in-class power quality with less than 5% total harmonic distortion means clean, smooth operation of your sensitive electronics and appliances.

Evolution™ Controller:  The next generation of intuitive controllers featuring a multilingual, two-line LCD text display with color-coded, backlit buttons.

Certified for 18" Installation to the Home:  Third-party certified to NFPA standards to be installed as close as 18” from the home’s exterior wall, provided it is located away from doors, windows, and fresh-air intakes, and unless otherwise directed by local codes.

Easy Installation:  When combined with a Generac Smart Switch, re-engineered connection points, and composite mounting pad that eliminates the need for a poured concrete base (unless specified by local codes), the Guardian Series 22 kW generator is easy to install.

Rated for Operation in Areas with Low Natural Gas Pressure:  In areas with low natural gas pressure, the Guardian Series 22 kW generator can operate on natural gas pressures of only 3.5” of water column.

All-Weather Aluminum Enclosure:  Our durable powder-coat finish helps make the sturdy, all-weather aluminum enclosure corrosion resistant, making it ideal for coastal, salt-air climates. It’s also able to withstand 150 mph winds.

Tool-less Fuel Conversion:  Switch between natural gas and LP fuel in the field in a few seconds, without the need for any tools.

Quiet-Test™ Mode:  Thanks to Quiet-Test, your Guardian Series 22 kW home standby generator runs its weekly self-test at a lower RPM for only five minutes. It’s quieter than other brands, and consumes less fuel. Choose your schedule - weekly, bi-weekly or monthly.

Mobile Link™ Compatible:  Take advantage of Generac’s Mobile Link cellular remote monitoring system and check on your generator’s status using your computer, tablet or smartphone, even when you are away. Sold separately.

24/7/365 Customer Support:  Power outages don’t always occur during normal working hours. That’s why Generac’s customer care call center—right here in Wisconsin—provides support any time of day or night, all year long. Generac is standing by 24/7, every minute of every day, to answer your questions.

5-year Limited Warranty

6551 Pre Packaged With:  RTSY200A3 - Generac 200 Amp Service Entrance Rated Automatic Transfer Switch in Nema 3R (Indoor/Outdoor Rated) Enclosure with Digital Power Management Technology (DPM), Flexible Fuel Line Connector, Base Fascia Trim Kit and attached Composite Mounting Pad.

Product Videos

The Generac Promise (PT57S:PT57)
At Generac, we promise that our automatic home generators will give you peace of mind and the power to live. And that
  • The Generac Pr...
    At Generac, we promise that our automatic home generators will...

Warranty Information

Manufactures Warranty: 5 Year Limited

Product Specifications

Model Number 6551
Series Guardian Series
Manufacturer Generac Power Systems
Made In USA Yes
Rated Watts 22kW LP/19.5kW NG
Rated Amps 91.6 LP/86.3 NG
Voltage 120/240V Single Phase
A/C Ton Rating 5 Ton
Enclosure Aluminum
UL Listed Yes
Decibel Rating 67 dbA @ 23 ft at Normal Operating Load
Starting System Automatic Start
Low Oil Alert Yes
Hour Meter Yes
Battery Requirement Group 26R, 12V, 525 CCA Min, Not Included
Mounting Pad Composite Base Attached
Product Weight 526 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 Natural Gas (NG) / Propane (LP)
NG Power Capacity 19.5kW
LP Power Capacity 22kW
NG Consumption @ Full Load 281 cu.ft/hr
NG Consumption @ 1/2 Load 184 cu.ft/hr
LP Consumption @ Full Load 3.68 gal/hr
LP Consumption @ 1/2 Load 2.16 gal/hr
Transfer Switch
Transfer Switch Model RTSY200A3
Transfer Switch Amps 200 Amps
Transfer Switch Circuits Service Rated - Whole House
ATS Poles 2 Pole
Transfer Switch Weight 39 lbs
Warranty Information
Consumer Warranty 5 Year Limited Warranty
Shipping Weight 559 lbs
Shipping Dimensions 44H x 51W x 26D
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Product Reviews

  1. An excellent product that keeps getting better

    Posted by Mike on 2nd May 2015

    An excellent value, aluminum enclosure, fascia wrap included for a nice finishing touch. Great updates including choice of test exercise interval, weekly, bi-weekly and monthly. Transfer switch included is service rated, with easily accessible wiring connections. Great warranty, great product. Just cant go wrong with Generac.

  2. very satisfied

    Posted by Max Eatman on 8th Apr 2015

    excellent product. Great value for the money. Norwall's customer service is excellent.

  3. Country Living

    Posted by Jim C on 9th Nov 2014

    My Mom and Dad are both in their 80's and live in the country. With the installation of the 6551 I can rest assured that they will never be without power, heat, ac and water. this is a great unit and worked perfectly upon startup. Should have installed this a lot sooner for them.
    By the way, my son-in-law also has one for his home. I live in a motorhome or I would have one also.

  4. Best Money I have Spent pn my Home

    Posted by Gatu on 9th Oct 2014

    This generator work great it starts and performs perfect when power goes out and comes back on!

  5. The Best Whole Home Generator

    Posted by Morris M. on 3rd Sep 2014

    After several hours of researching home generators, I found that the air cooled generac model 6551 was by far the best generator for me. It is the best buy and the nicest looking one on the market and really fits in with the landscape nicely. The warranty is great and the installation guide was easy to understand.

  6. My New 22kW Generac

    Posted by Charles on 28th Aug 2014

    On the coast of Virginia, a storm is always a possibility so whenever the next outage comes, I'll be more than ready with this brand new Generac model 22kW w/aluminum enclosure. I have 3 A/C units in addition to the normal circuit requirements and this unit is set to run them all. Just in case, the smart switch is set up to control my A/C thermostats if one of the units needs to be shut down temporarily. Norwall has the best pricing, great customer service and the shipping time was FAST! I highly recommend Norwall for all your power needs.
    Charles, Poquoson VA

  7. New Generac air cooled 22KW #6551

    Posted by Richard P. on 25th Aug 2014

    Ok, so I've always wanted a whole home generator living in SE Texas. Located an installer and he said don't buy from anyone but NORWALL... So I pick up the phone and call place my order. I order on a Friday and my generator arrives the next Tuesday, I'm floored by the quick delivery. Installer shows up, has this unit installed in a matter of half a day.

    This unit fires up first shot, and Ive got power through the entire house running two ac units, 5 and 3 ton units, plus my pool equip. I'm completely amazed. This unit is so quiet I cant even hear it running from inside but know the power is there...

    So we are not looking forward to any major storms, but when it comes-- we are well prepared...

    Norwall is awesome, buy with confidence. The only folks to deal with if your looking for a generator and this new 22kW is more than I ever thought it would be. Thanks!!!

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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.

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