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Generac Guardian™ 11kW Standby Generator System (50A 12-Circuit Automatic Switch)

Generac Guardian Electric Generators and Accessories
Model: 6437
(Based on expert analysis, manufacturer ratings and customer reviews)
4.8 out of 54.8 out of 54.8 out of 54.8 out of 54.8 out of 5
35 Reviews
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  • Features
  • Specs
  • 14
  • 35
  • Articles
  • Accessories
Run Watts
Rated Watts
120/240 Single-Phase

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."

Fully Automatic Operation
Operates On Clean Burning, Efficient Natural Gas or LP (Vapor)

Generac OHVI Air-Cooled Engine
Features plateau honed cylinder walls and plasma-moly rings
Full pressure lubrication system w/ 2 year oil change interval

Skewed Rotor Design For Smooth Output Waveform "Clean Power"
Automatic voltage regulator equipped for +/- 1% regulation

Evolution™ Digital Controller Monitors & Controls All Functions
Provides system status for wireless monitors & Mobile Link™

Sound Attenuated Weather Proof Enclosure
Attractive styling with lockable access doors
Incorporates electrostatically applied epoxy paint technology
Sound dampening enclosure limits sound pressure to a low 62dB(A)

Includes 12 Circuit Load Center Style Auto Transfer Switch (50A)
5' Pre-wired External Connection Box From Wall to Generator
30' Pre-Wired Indoor Conduit From Switch To External Box
2' Pre-Wired Indoor Conduit From Transfer Switch To Main Panel
12" flexible fuel line and manual
Built-in Battery Charger (Battery Sold Separately)

5-Year Limited Warranty & 24/7/365 Customer Care
Engine Brand
Generac OHVI
530 CC
Consumer Engine Warranty
5 Years
Commercial Engine Warranty
5 Years
Engine RPM
3600 RPM
Low Oil Alert/Shutdown
Product Specs
120/240 Single-Phase
60 Hertz
Surge Watts
11000 Watts
Rated Watts
11000 Watts
Fuel Type
LP/Natural Gas
NG Power Capacity
10000 Watts
LP Power Capacity
11000 Watts
NG Fuel Consumption @ 50% Load
124 (BTU: 124,000 BTU/HR) ft³/hr
NG Fuel Consumption @ 100% Load
195 (BTU: 195,000 BTU/HR) ft³/hr
LP Fuel Consumption @ 50% Load
1.18 (BTU: 107,085 BTU/HR) gallons/hr
LP Fuel Consumption @ 100% Load
1.92 (BTU: 174,240 BTU/HR) gallons/hr
Rated Amps
46 @ 240 Volts (Single Phase) Amps
Decibel Rating @ 7m
63 dbA
Transfer Switch
Automatic (Included)
Transfer Switch Amperage
Not Included (525 CCA)
A/C Ton Rating
Transfer Switch Style
Pre-Wired (12-Circuit)
ATS Load Prioritizing
Not Compatible
ATS Load Shedding
Not Compatible
ATS Poles
2 Poles
ATS Service Disconnect
Cooling System
Air Cooled
UL Listed
Grade Type
Transfer Switch Circuits
15A 120V
20A 120V
30A 240V
40A 240V
Made in USA
407 Pounds
Product Style
Standby Generator
Product Length
48 Inches
Product Width
25 Inches
Product Height
29 Inches
Consumer Warranty
5 Years
Commercial Warranty
5 Years
  14 Questions
Q: Are there recommended installation distances from other items? I have an AC unit near where I would like to place the generator. Also, would it be okay to be under a porch? There is about 5' from the ground to the bottom of the porch.
by Matt from Pennsylvania on June 18, 2014

A: The minimum distances can be found in the installation guide we have available on the site on the product page under the specs tab in the download document section.....

Installation Guide

The unit needs at least 3 feet clearance on the sides of the unit for proper air flow and 3 feet from the front for proper maintenance. Also, the unit requires a minimum of 5 feet clearance from the top of the unit. These units cannot be installed under a porch. These units also require a minimum of 5 feet from any window, door or ventilation opening.

We recommend you consult with your local inspector or AHJ (Authority Having Jurisdiction) for your local code requirements as they can sometimes supersede the manufacturers recommendations.

by Mike, Product Expert

Q: I'm interested in the Generac 14 kw standby generator and I want to power it with natural gas. All your other Generac standby generators show a wattage loss of about 2kW when powered with natural gas, but this one does not show a loss in the specs I have reviewed. Is this a misprint in the specs or is this a true output? If I power it with natural gas will it deliver 12 kW or 14 kW?
by Albert Leblanc from Michigan on May 06, 2014

A: This is not a misprint in the specification. The unit will produce 14kW when operating on Natural Gas and LP as tested at the factory.

Also noted on the manufacturers specification sheets is the following....

"Maximum wattage and current are subject to and limited by such factors as fuel BTU/megajoule content, ambient temperature, altitude, engine power and condition, etc. Maximum power decreases about 3.5 percent for each 1,000 feet (304.8 meters) above sea level; and also will decrease about 1 percent for each 6° C (10° F) above 16° C (60°F)."

Specification sheets can be found on the individual product pages under the Specs tab and within the download document section.

by Mike, Product Expert

Q: Can the Generac model 6437, with 50 amp transfer switch, be used in my home with 100 amp service?

by Nicky from Maine on April 22, 2014

A: Yes, the prewired 50A essential circuit transfer switch can be used in an application with 100A utility service.

The switch is installed as a sub-panel after your main panel allowing you to power specific circuits during a power outage.

by Mike, Product Expert

Q: I am thinking about purchasing an 11kW Generac propane generator for the house. Approx. how long will 100 gallons of propane run the generator or how many gallons an hr. does it burn?

by Charles Cieliesz from Florida on February 13, 2014

A: The minimum tank size recommendation is 250 gallons per Generac due to the starting BTU/HR requirement of the generator and the overall run time.

The 11kW unit has the following fuel consumption rate found in the specs tab on the generator product page....

LP Consumption (50% Load) 1.18 gallons/hr (BTU: 107,085 BTU/HR)
LP Consumption (100% Load) 1.92 gallons/hr (BTU: 174,240 BTU/HR)

We recommend you consult with your LP provider for proper sizing based on your local area temperatures as temperature affects the BTU output from an LP tank.

by Mike, Product Expert

Q: Regarding the Generac 7kW fueled by Nat Gas . Spec states fuel consumption is 85 ft3/hr for 1/2 load. My question is what is this equivalent to in CCF?

by Ed from Pennsylvania on February 06, 2014

A: Natural Gas is usually measured by volume in the United States and is stated in cubic feet. A cubic foot of gas is the amount of gas needed to fill a volume of one cubic foot under set conditions of pressure and temperature.

To measure larger amounts of natural gas, "CCF" (centum cubic-feet) is used to denote 100 cubic feet, and "MCF" (mil cubic-feet) is used to denote 1,000 cubic feet.

With that said, due to the small amount of consumption you wouldn't convert the current ft3/hr to CCF.

However, if you are trying to calculate the cost in relation to therms listed by your natural gas company the conversion is 1000 ft3/hr equals 10 therms.

by Mike, Product Expert

Q: Would winter time installations of automatic generators be good or bad?

by Ron Mills from Michigan on December 30, 2013

A: You can install a generator at any time. However, it would be based on if you are putting down a concrete base as it will not set in cold temperatures. If you are putting down crushed stone or pea gravel it should be no problem.

You can also go with a GenPad (Gen Manufacturer Specific) which is a preform concrete base, so no concrete curing time. These can be installed in any temperature.

Generac GenPads

by Mike, Product Expert

Q: I have a low pressure nat. gas line in my residence, what is the largest generator I will be able to run without doing major updates ?

by Chuck from Ohio on December 10, 2013

A: The Generac line of home standby systems can now operate on low pressure natural gas. Their low fuel pressure requirement is 3.5" to 5" of water column (1" of water column = 0.036 PSI).....0.123 PSI to 0.18 PSI. This would be for all sizes from 8kW up to 20kW.

Proper sizing of the generator is crucial to the success of any generator installation and requires a good working knowledge of electricity and its characteristics, as well as the varying requirements of the electrical equipment comprising the load.

A certified electrician needs to be consulted for proper sizing and installation of any generator.

When analyzing the electrical load, consult the manufacturer’s nameplate on each major appliance or piece of equipment to determine its starting requirements in terms of amps and voltage which can be calculated to watts using Ohms Law (Amps x Volts = Watts).

When choosing the generator output select a rating that is approximately 20 to 25% higher than the peak load (for example, if the load is about 8 kilowatts, select a 10 kW generator).

A higher rated generator will operate comfortably at approximately 80% of its full capacity and will provide a margin of flexibility if the load increases in the future.

Note: Applications such as commercial, all-electric homes, heat pump systems or geothermal systems require special installation procedures and a certified electrician must be contacted to evaluate and install these types of systems.

by Mike, Product Expert

Q: If I'm not around when my home standby generator is running, what type of protections systems do the Generac units have?
by Josh from New Jersey on November 13, 2013

A: The generator may have to run for long periods of time with no operator present to
monitor the engine/generator conditions. Therefore, the generator is equipped with a number of systems to automatically shut down the unit to protect it against potentially damaging conditions. Some of these systems are as follows:

• Low Oil Pressure Sensor
• High Temperature Sensor
• Overcrank Sensor
• Overspeed Sensor
• RPM Sensor
• Under-frequency Sensor
• Undervoltage Sensor
• Overvoltage Sensor
• Internal Failure Sensor
• Low Battery Voltage Alarm

The control panel contains a display which alerts the operator when a fault condition occurs. The above list is not all inclusive. For more information about alarms and control panel operation, see Section 3 (Operation) in the owner's manual.

by Mike, Product Expert

Q: What type of oil should I use in my Generac home standby generator?
by Jim from Illinois on November 11, 2013

A: The maintenance section in the Generac's home standby owner's manual lists that the oil type is based on temperature ranges specific in your area.....

SAE-30 above 32º F (0º C)
10W-30 between 40º and -10º F (4º and -23º C)
Synthetic 5W-30 for all temperature ranges

All new models come with SAE-30 oil in them and have been test run at the factory for 25 hours and no break-in is required. The first oil change would be at 2 years or 200 hours, whichever comes first.

by Mike, Product Expert

Q: I'm not sure if this falls into the repair area but, I'm concerned about the sound this generator produces. Is there a way to lower that? Is there sound proofing approved for use for the interior walls of this type of home standby? My neighbors bedroom window will be 20ft from where I plan to install the generator. I would prefer doing something inside the generator as apposed to some type of fencing or other external methods.

by Mark H. from New Jersey on October 23, 2013

A: The manufacturers make every effort to reduce the sound of their generators as best they can keeping within NFPA and UL requirements. There are currently no options or parts available to install inside home standby systems to reduce their db(A) levels.

Your only option is location or sound barriers installed around the unit while keeping within NFPA and manufacturers distance requirements for proper fire protection, air intake and exhaust output.

We recommend consulting with your local inspector or AHJ (Authority Having Jurisdiction) as to the specific local code requirements.

by Mike, Product Expert

Q: I have a new 2013 Generac generator and I'm wondering what oil it came with? I would like to top it off properly after the installation.

by John from New Jersey on October 18, 2013

A: The Generac 2013 automatic standby generators are shipped with a SAE 30 non-synthetic oil. If you are located in an area that receives snow, it is recommended to perform an oil and filter change to switch to a synthetic 5W-30 oil to promote proper generator operation. The cold weather kit is also recommended.

The appropriate intervals for oil changes and other maintenance items will be located in the owner’s manual in the Maintenance Schedule.

Current production models do not require any break in, so if the Maintenance Schedule in the owner's manual indicates that oil changes only need to be done every 2 years or 200 hours, you could drain the existing oil and switch to synthetic 5W-30 right away.

by Mike, Product Expert

Q: What is the recommended time frame to change the break-in oil on my Generac 20kW generator?

by Karin Green from New Jersey on August 10, 2013

A: All of the new 2013 Generac Home Standby generators have been pre-run at the factory for 25 hours. So, no break-in period is required.

by Mike, Product Expert

Q: I just purchased a 11kW generator and would like to know the max distance that I can run 1/2 inch steel pipe to my generator?

by Spencer Aucoin from Louisiana on June 27, 2013

A: The fuel pipe requirements are:

Natural Gas:

1/2" - Cannot Use
3/4" - Max 20 Feet
1" - Max 85 Feet
1-1/4" - Max 370 Feet

Liquid Propane Vapor: (Note: Pipe sizes are using a second stage regulator)

1/2" - Cannot Use
3/4" - Max 70 Feet
1" - Max 255 Feet
1-1/4" - Max 1000 Feet

Natural Gas Pressure: 3.5 - 7 Inches Of Water Column
Liquid Propane Vapor: 10 - 12 Inches Of Water Column

***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: What is the difference between the Generac model 5871 and their new model 6437 since they are about the same size?
by Mike from Illinois on May 23, 2013

A: Generac went ahead and improved on the design, warranty and ease of installation after listening to consumer reviews and technicians.

They bumped up the warranty an additional 2 years to give it a solid 5 year overall which is one of the highest rated on the market.

They improved on the generator controller by upgrading to a new technology and moved from their very good Nexus design to the new and improved Evolution controller. This new controller has a back-lit interface with LED's that shows the generator status at a glance.

The new Evolution controller includes maintenance reminders and logs, battery condition (no guessing) and over a half-dozen additional alarms the Nexus controller did not have. This thing rocks!

They upgraded the engine to include a no choke carburetor which helps with all weather starting. They changed the fuel selector for natural gas and LP to an easy knob that is easy to access and change fuel type with ease (No tools required).

For the installers they made several changes to help with installation costs and time, minimize errors and accommodate current and future electric code interpretations by re-engineered some of the wiring connections.

With the changes to the carb and engine they were able to change the low fuel pressure rating for Natural Gas down from 5" of Water Column to 3.5" of Water Column. This will help tremendously with low fuel pressure areas in the country so the meters do not need to be changed as often.

With all of these upgrades they have performed I believe Generac's newest model is one of the best out there and comes highly recommended.

by Mike, Product Expert

Generac Guardian 6437 Reviews & Ratings
Overall Rating
4.8 out of 54.8 out of 54.8 out of 54.8 out of 54.8 out of 5
High Quality (16)
I'd Buy It Again (14)
Price (14)
Quiet (6)
Fast (6)
Heavy (1)
Bad Instructions (1)
Arrived With 71 Hours On... (1)
No Closure Plugs For The... (1)
97% of respondents would recommend this product to a friend
35 Reviews  Sort by 
Jack D.
Auburn, IN
Purchased from Electric Generators Direct
Purchased 9/6/16
Most Helpful Positive Review
5 out of 55 out of 55 out of 55 out of 55 out of 5
Second Purchase Of Standby Generator
In 2000, I purchased a Generac 10K generator for my rural lake home. I completed the physical installation and my son-in-law (an electrician) made the electrical connections.

We reviewed the startup instructions and everything worked flawlessly. This model had a 120V convenience outlet in the battery area, so I purchased a thermo-controlled batter warming pad for around 8 or 9 dollars and placed it under the battery.

Since my home was dependent on electricity for water, the Generac saved... more
Jack Recommends This Generac Guardian Product
Mike, the Generator Expert
Product Expert
This should be covered under your warranty and would need to be handled by a servicing dealer. I'd suggest contacting Generac directly @ 888-436-3722 or Generac Dealer Locator
Was this review helpful?
Richard P.
Middletown, DE
Purchased from Electric Generators Direct
Purchased 9/15/16
4 out of 54 out of 54 out of 54 out of 54 out of 5
Customer Service
Jim Lustyk was outstanding, There were problems with the order and he straighten them, out quickly with no impact on me, the customer. Great job,
Richard Recommends This Generac Guardian Product
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Ralph W.
Dearborn Heights, MI
Purchased from Electric Generators Direct
Purchased 9/14/16
5 out of 55 out of 55 out of 55 out of 55 out of 5
I Think It Is A Very Good Product
After the generator was connected it has been working just great. It runs for 12 minutes every week and we haven't had a power outage and haven't had to use it for our power.
Pros: High Quality, Price, I'd Buy It Again, Quiet
Ralph Recommends This Generac Guardian Product
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Gene C.
Cleveland, GA
Purchased from Electric Generators Direct
Purchased 9/8/16
5 out of 55 out of 55 out of 55 out of 55 out of 5
Wonderful Piece Of Mind With This Generator
Ive dreamed about having a house generator for years but either didn't have the money or used what i had on other toys. Finally I made the move and bought this Generac. Its perfect in power, uses propane as I wanted and came in a complete kit. The downside is there is a lot of electronic circuit boards which worry me in the event of an EMP and I'm not sure if the generator case will help shield it at all. Would love to know. It runs once a week to test itself flawlessly. I'm actually hopeful... more
Pros: High Quality, Price, Exceeded Expectations, Propane
Gene Recommends This Generac Guardian Product
Mike, the Generator Expert
Product Expert
In regards to your question about the generator enclosure. I would contact Generac directly 888-436-3722.
Was this review helpful?
Kevin J.
Charlestown, RI
Purchased from Electric Generators Direct
Purchased 6/4/13
Total Helpful Votes
14 Helpful Votes
5 out of 55 out of 55 out of 55 out of 55 out of 5
Works Perfectly
Just finished installing last week and I woke up this morning the generator was running I had my computer running and after an hour power was restored my lights and computer did not even blink I could not be happier. Love it!
View Image
Pros: Durable, Easy To Use, Reliable, I'd Buy It Again
Kevin Recommends This Generac Guardian Product
Kevin Would Recommend Electric Generators Direct To A Friend
Web Site


"Very happy with Generators Direct"
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Dave F.
Thorndale, PA
Purchased from Electric Generators Direct
Purchased 8/22/13
Total Helpful Votes
18 Helpful Votes
5 out of 55 out of 55 out of 55 out of 55 out of 5
Go Direct
As a electrical contractor we put a lot generators in. This is the first time I used Generators Direct. They were great from ordering to delivery and cost. Thanks
Pros: I'd Buy It Again, Quiet, Fast, High Quality
Dave Recommends This Generac Guardian Product
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Christopher B.
Parkton, MD
Purchased from Electric Generators Direct
Purchased 8/7/13
Total Helpful Votes
17 Helpful Votes
5 out of 55 out of 55 out of 55 out of 55 out of 5
11 Kw Propane Unit
Very smooth transaction with great communication from the trucking company also .
Great shipping crate/ protection
Very complete wiring kit
Good directions
Nice looking , pretty quite unit.

No closures for the lifting holes ( to keep mice and critters out )
The lp/ng selector knob would not move , luckily it must have been on the lp setting ( it was hard to tell what setting it was on also ) because the engine started right up and ran pretty smooth.

Overall a really nice... more
Pros: Quiet, Price, High Quality, I'd Buy It Again
Cons: No Closure Plugs For The Lifting Holes
Christopher Recommends This Generac Guardian Product
Mike, the Generator Expert
Product Expert
Generac does not make any close plugs for the lifting holes on their air-cooled generators. However, they do offer a Fascia Base Trim Kit. It will cover up those holes and provide a finished looked to your standby generator.
Christopher Would Recommend Electric Generators Direct To A Friend
Web Site


"Fast complete shipping . Good communication from the trucking company also."
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Frank K.
Mesa, AZ
Purchased from Electric Generators Direct
Purchased 1/28/15
Total Helpful Votes
15 Helpful Votes
2 out of 52 out of 52 out of 52 out of 52 out of 5
No Actual Generac Warrenty On 11kw Unit
I bought the generator. Paid to have it hooked up. It took over a month to get it installed. The generator ran for less than 1/2 hour and blew up. Generac doesn't pay the authorized companies enough to cover the actual cost of repairs so I had to pay the repair company direct. After paying $637 to have them come to my home I got an estimate of between $1500 to $4000 to replace the magneto half of this brand new generator.

A magnet separated from the flywheel and metal parts and dust are all... more
Frank Does Not Recommend This Product
Mike, the Generator Expert
Product Expert
We are working with Generac to get this resolved for you.
Manufacturer Response
Brand Rep
We would like to apologize for the issues that you have experienced with your automatic standby generator. To address your concerns regarding warranty coverage, we wish to assure you that any applicable warranty coverage will be provided to a unit if/when it is determined through diagnostic work that such coverage applies. Once diagnostic work and warranty work is provided, we will work with the service provider for reimbursement. So that we can discuss your personal case with you directly, we would like to request having you contact us at 888-GENERAC (436-3722) at your earliest convenience. We look forward to corresponding with you in the near future.
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Raymond P.
Orland, PA
Purchased from Electric Generators Direct
Purchased 10/10/13
Total Helpful Votes
10 Helpful Votes
5 out of 55 out of 55 out of 55 out of 55 out of 5
Great Experience
Called and ordered the Generac 11K unit late on a Thursday and it was delivered on the following Tuesday afternoon. Mo problems whatsoever. Had my own electrician and plumber install the unit and the job was completed in 4 hours. Test run the unit and all went well and now my wife and I have the piece of mind whenever a storm may hit.
Pros: I'd Buy It Again, High Quality, Quiet, Price
Raymond Recommends This Generac Guardian Product
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Irene M.
Ashtabula, OH
5 out of 55 out of 55 out of 55 out of 55 out of 5
Preace Of Mind
I live on the North Coast (Lake Erie) and power outages are common. I also have springs beneath my house that require a sump pump to run at at constant pace. One week after the Guardian generator was installed, we had a brief power outage and I heard the Generator kick on. I was so relieved to know that my basement would stay dry because the sump pump would continue to run and that despite the sub-zero temperatures my pipes would not freeze. It was the most welcomed sound I ever heard! Best... more
Pros: I'd Buy It Again, Price, Fast, Easy To Use
Irene Recommends This Generac Guardian Product
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Ed O.
Purchased from Electric Generators Direct
Purchased 9/30/14
4 out of 54 out of 54 out of 54 out of 54 out of 5
So Far...flawless
Sure, this unit has it's quirks. No deal breakers though. We had it installed by an electrician who has installed many. This really helped with locating the switch and wiring, and deciding what areas of the home to connect for protection in case of a power outage. Once the unit was connected, we disconnected the main power coming in to the house and this generator started immediately and provided power to all the circuits we needed in the house and garage. The unit cycles itself every... more
Ed Recommends This Generac Guardian Product
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4.9 out of 54.9 out of 54.9 out of 54.9 out of 54.9 out of 5
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Shop for the Generac Guardian™ 11kW Standby Generator System (50A 12-Circuit Automatic Switch) at Electric Generators Direct. Research Generac Guardian 696471064377 standby generators air-cooled generator online. Find Generac Guardian 6437 standby generators air-cooled generator & Guardian 11kW Generator 50 amp features and specifications.