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Generac Guardian™ 20kW Aluminum Home Standby Generator

Generac Guardian™ 20kW Aluminum Home Standby Generator
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Model: 6250
(Based on expert analysis, manufacturer ratings and customer reviews)
4.5 out of 54.5 out of 54.5 out of 54.5 out of 54.5 out of 5
Number of Reviews (6)
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  • Product Description
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    Product Q&A
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Product Description
+
Grade
Style
Run Watts
20,000
Rated Watts
Voltage
120/240 Single-Phase
Fuel
Engine
Grade
Emergency
Style
Standby (Air Cooled)
Run Watts
20,000
Voltage
120/240 Single-Phase
Fuel
LP/Natural Gas
Engine
Generac OHVI


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."

Features
Features
  • Fully Automatic Operation When Paired With Generac Smart Switch™
  • Generac OHVI Air-Cooled Engine
  • Features plateau honed cylinder walls and plasma moly rings
  • Full pressure lubrication system w/ 2 year oil change interval
  • Aids in cooling the engine for longer life
  • Operates On Clean Burning, Efficient Natural Gas or LP (Vapor)
  • 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 acess doors
  • Incorporates electrostatically applied epoxy paint technology
  • Sound dampening enclosure limits sound pressure to a low 66dB(A)
  • Matching fascia kit and 12" flexible fuel line included
  • Built-in Battery Charger (Battery Sold Separately)
  • Automatic Transfer Switch - ATS (Sold Separately)
  • Select the ideal ATS & PPM modules for load shed capabilities
  • Automatic Operation Only & Listed to UL2200 Standards For Safety
  • 5-Year Limited Warranty & 24/7/365 Customer Care
Specifications
Product Specs
Voltage
120/240 Single-Phase
Frequency
60 Hertz
Rated Watts
20000 Watts
Surge Watts
20000 Watts
Fuel Type
LP/Natural Gas
NG Power Capacity
18000 Watts
LP Power Capacity
20000 Watts
NG Fuel Consumption @ 50% Load
205 ft³/hr
NG Fuel Consumption @ 100% Load
308 ft³/hr
LP Fuel Consumption @ 50% Load
2.08 gallons/hr
LP Fuel Consumption @ 100% Load
3.85 gallons/hr
Rated Amps
83 Amps
Decibel Rating @ 7m Learn More Sound levels are measured in decibels (dB). The lower the decibel rating, the less noise the product makes. As an example, a ticking watch is 20 dB while on the other end of the scale, a lawn mower is around 90 dB.
66 dbA
Transfer Switch
Automatic (Not Included)
Battery
Not Included (525 CCA)
Enclosure
Aluminum
A/C Ton Rating
5-Tons
Mounting Pad
Composite (Included)
Cooling System
Air Cooled
UL Listed
Yes
Grade Type
Emergency
Engine
Engine Brand
Generac OHVI
CC
999 CC
Consumer Engine Warranty
5 Years
Commercial Engine Warranty
5 Years
Engine RPM
3600 RPM
Low Oil Alert/Shutdown
Yes
Overview
Weight
541 Pounds
Made in USA
Yes
Consumer Warranty
5 Years
Commercial Warranty
5 Years
Product Style
Standby Generator
Product Length
48 Inches
Product Width
25 Inches
Product Height
29 Inches
UPC
696471062502
Grade
Style
Run Watts
20,000
Rated Watts
Voltage
120/240 Single-Phase
Fuel
Engine
Grade
Emergency
Style
Standby (Air Cooled)
Run Watts
20,000
Voltage
120/240 Single-Phase
Fuel
LP/Natural Gas
Engine
Generac OHVI


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."

Features
Features
  • Fully Automatic Operation When Paired With Generac Smart Switch™
  • Generac OHVI Air-Cooled Engine
  • Features plateau honed cylinder walls and plasma moly rings
  • Full pressure lubrication system w/ 2 year oil change interval
  • Aids in cooling the engine for longer life
  • Operates On Clean Burning, Efficient Natural Gas or LP (Vapor)
  • 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 acess doors
  • Incorporates electrostatically applied epoxy paint technology
  • Sound dampening enclosure limits sound pressure to a low 66dB(A)
  • Matching fascia kit and 12" flexible fuel line included
  • Built-in Battery Charger (Battery Sold Separately)
  • Automatic Transfer Switch - ATS (Sold Separately)
  • Select the ideal ATS & PPM modules for load shed capabilities
  • Automatic Operation Only & Listed to UL2200 Standards For Safety
  • 5-Year Limited Warranty & 24/7/365 Customer Care
Specifications
Product Specs
Voltage
120/240 Single-Phase
Frequency
60 Hertz
Rated Watts
20000 Watts
Surge Watts
20000 Watts
Fuel Type
LP/Natural Gas
NG Power Capacity
18000 Watts
LP Power Capacity
20000 Watts
NG Fuel Consumption @ 50% Load
205 ft³/hr
NG Fuel Consumption @ 100% Load
308 ft³/hr
LP Fuel Consumption @ 50% Load
2.08 gallons/hr
LP Fuel Consumption @ 100% Load
3.85 gallons/hr
Rated Amps
83 Amps
Decibel Rating @ 7m Learn More Sound levels are measured in decibels (dB). The lower the decibel rating, the less noise the product makes. As an example, a ticking watch is 20 dB while on the other end of the scale, a lawn mower is around 90 dB.
66 dbA
Transfer Switch
Automatic (Not Included)
Battery
Not Included (525 CCA)
Enclosure
Aluminum
A/C Ton Rating
5-Tons
Mounting Pad
Composite (Included)
Cooling System
Air Cooled
UL Listed
Yes
Grade Type
Emergency
Engine
Engine Brand
Generac OHVI
CC
999 CC
Consumer Engine Warranty
5 Years
Commercial Engine Warranty
5 Years
Engine RPM
3600 RPM
Low Oil Alert/Shutdown
Yes
Overview
Weight
541 Pounds
Made in USA
Yes
Consumer Warranty
5 Years
Commercial Warranty
5 Years
Product Style
Standby Generator
Product Length
48 Inches
Product Width
25 Inches
Product Height
29 Inches
UPC
696471062502
Product Specs
+
Specifications
Product Specs
Voltage
120/240 Single-Phase
Frequency
60 Hertz
Rated Watts
20000 Watts
Surge Watts
20000 Watts
Fuel Type
LP/Natural Gas
NG Power Capacity
18000 Watts
LP Power Capacity
20000 Watts
NG Fuel Consumption @ 50% Load
205 ft³/hr
NG Fuel Consumption @ 100% Load
308 ft³/hr
LP Fuel Consumption @ 50% Load
2.08 gallons/hr
LP Fuel Consumption @ 100% Load
3.85 gallons/hr
Rated Amps
83 Amps
Decibel Rating @ 7m Learn More Sound levels are measured in decibels (dB). The lower the decibel rating, the less noise the product makes. As an example, a ticking watch is 20 dB while on the other end of the scale, a lawn mower is around 90 dB.
66 dbA
Transfer Switch
Automatic (Not Included)
Battery
Not Included (525 CCA)
Enclosure
Aluminum
A/C Ton Rating
5-Tons
Mounting Pad
Composite (Included)
Cooling System
Air Cooled
UL Listed
Yes
Grade Type
Emergency
Engine
Engine Brand
Generac OHVI
CC
999 CC
Consumer Engine Warranty
5 Years
Commercial Engine Warranty
5 Years
Engine RPM
3600 RPM
Low Oil Alert/Shutdown
Yes
Overview
Weight
541 Pounds
Made in USA
Yes
Consumer Warranty
5 Years
Commercial Warranty
5 Years
Product Style
Standby Generator
Product Length
48 Inches
Product Width
25 Inches
Product Height
29 Inches
UPC
696471062502
Reviews
(6)
+
Generac Guardian 6250 Reviews & Ratings
Product Q&A
(17)
+
Search Product Q&A's Answered by Jared, the Generator Expert
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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.
Matt 
from Pennsylvania 
June 18, 2014
Answer
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.
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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?
Albert Leblanc 
from Michigan 
May 06, 2014
Answer
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.
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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 ?
Chuck 
from Ohio 
December 10, 2013
Answer
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.
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Guys I need a 20 kW natural gas home stand by with a 150A service rated transfer switch. Is this available as a package deal?
Harry Donovan 
from Virginia 
December 01, 2013
Answer
At this time Generac does not pre-package their home standby systems with a 150A transfer switch. You would need to purchase each item individually.....

Generac Generator Model 6250

Generac Switch Model RTSY150A3

Another option would be the Briggs & Stratton line of home standby units which do come with a 150A packaged option....The following link shows the available prepacked 150A home standby systems....

150A Prepackaged Home Standby Systems.
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Can I use the 100 amp 16 circuit transfer switch with a 20 KW Generac?
George Bristol 
from Nebraska 
November 23, 2013
Answer
You cannot use the 16 circuit Generac transfer switch with the 20kW Generac home standby unit. The internal wiring is not suitable for the amperage output capacity of the 20kW unit.

The following switches are recommended for use with the 20kW Generac unit allowing specific circuits......

Generac GenReady Indoor Load Center - Model 5449

Generac GenReady Outdoor Load Center - Model 5454

Generac LTS Load Center with Load Shedding (16 Circuit) - Model RTSJ200A3
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The install guide says The minimum LP tank size is 250 gallons. My customer was hoping to avoid this type of tank since it is required to be at least 10' from the house and would need trenching where ledge is. Any idea why they specify it like this? My customer wanted to go with less obtrusive 120 gallon tanks that are allowed next to the house. Is it just based on capacity or is it more to do with pressure or regulators?
Rob Saccardo 
from Massachusetts 
November 21, 2013
Answer
The tank size recommendation is based on BTU output, capacity and temperature. However, some propane suppliers will state a 120 gallon tank is sufficient for a 20kW standby generator but a 120 gallon tanks usable fuel amount is less then the tank size which will also vary depending on temperature.

The fuel consumption of a 20kW is 2.08 gallons per hour when operating at 1/2 load capacity and if calculated into a days use you will be using just under 50 gallons of fuel.

A 120 gallon tank has 72 usable gallons with the BTU output varying depending on temperature. A 120 Gallon tank BTU/HR output capacity based on 40 degrees F is 248,240 BTU/HR and a 20kW, at start-up, requires 349,388 BTU/HR which is more then a 120 gallon tank can supply. To properly size a generator to your fuel source you need to size it to it full load start-up BTU/HR requirements.

A 250 gallon tank has 150 usable gallons with the BTU output also varying depending on temperature. A 250 Gallon tank BTU/HR output capacity based on 40 degrees F is 507,600 BTU/HR and is well within the requirements of the 20kW generator.

With that said, a 120 gallon tank does not offer enough BTU/HR output capacity to supply a 20kW generator. This is why Generac recommends a minimum 250 gallon tank with strong recommendations for a larger tank.
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What type of oil should I use in my Generac home standby generator?
Jim 
from Illinois 
November 11, 2013
Answer
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.
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Jim I have a 100 amp Pre-Nexus service rated transfer switch. Can I use this with a nexus generator? I've heard there is some special wiring for the battery charger to work
J. Depp 
from California 
November 04, 2013
Answer
Thank you for your interest in Electric Generators Direct!

There is a special kit that needs to be added to the switch to accept the 120V connection which provides the power to the internal generator controller for the charger. These kits are available from your local Generac dealer - Part Number: 0H92540SRV.


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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.
John 
from New Jersey 
October 18, 2013
Answer
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.
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Q: I just purchased a 20KW generator and would like to know the max distance that I can run 1/2 inch steel pipe to my generator?
Johnnymack 
from Rhode Island 
September 28, 2013
Answer
Per Generac you cannot us 1/2 inch pipe at all on a 20kw or any of their air cooled generators as this does not provide enough volume of fuel to the unit.

Here are the fuel pipe requirements on a 20kw Generac Model 6244 or 6250.....

Natural Gas:

1/2 Inch: Cannot Use
3/4 Inch: Cannot Use
1 Inch: Max Distance 20 Feet
1-1/4 Inch: Max Distance 130 Feet
1-1/2 Inch: Max Distance 305 Feet

Liquid Propane Vapor:

1/2 Inch: Cannot Use
3/4 Inch: Max Distance 15 Feet
1 Inch: Max Distance 115 Feet
1-1/4: Inch: Max Distance 480 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.
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What is the recommended time frame to change the break-in oil on my Generac 20kW generator?
Karin Green 
from New Jersey 
August 10, 2013
Answer
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.
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I just purchased the Generac Guardian 20kw model 6244 from your site. I am planning to pour the base this weekend for the generator. My question is what size should I make my pad? I would like to set the anchors in the concrete before it dries. What kind of anchors is recommended and what size should they be? What Type of oil is recommended and do I need to purchase an oil filter?
Mark Muczynski 
from Michigan 
July 30, 2013
Answer
The installation drawing is available on the site under the specs tab in the download document section. This will provide dimensions of the generator where you will want to make the pad at least 6 inches larger on all sides. You will also find the location of the holes for mounting the unit to the concrete pad. Generac recommends 3/8 inch lag bolts designed for concrete.

Installation Drawing

You will also find the owner's manual available where it discusses proper maintenance and oil requirements based on temperatures in your area.

Owner's Manual

When changing the oil it is also recommended to change the oil filter. The following link is for the recommended maintenance kits available for the Generac model 6244...

Basic Maintenance Kit

Maintenance Kit with 5W30 Synthetic

Maintenance Kit with 10W30 Synthetic

Maintenance Kit with 10W30 Standard
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I need a 20kW natural gas generator. But they seem to only come with a 200A panel. I believe I need a 300A panel. Is there a big price difference in purchasing a 300A panel with the generator? I didn't see it on your website. Can you tell me the price?
Peter Kearns 
from New Jersey 
July 13, 2013
Answer
If you have a specific application that does not meet the prepackaged units you would purchase the items individually instead. The packaged systems are put together by the appropriate manufacturer and cannot be altered.

Briggs does not offer a 300A switch so you would need to go to the larger 400A switch if you intend on powering the entire home and that system is already prepackaged. (Model 40396).

Generac does offer a 300A switch so you would purchase the generator by itself (Model 6250) and the switch separately (Model RTSY300A3). Just add each item to the cart and enter your state and zip for the total.

We do recommend consulting with a certified electrician for proper generator sizing and installation.
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Could you please advise regarding the Generac 6244 vs the 6250? The pros and cons of one vs the other, any preference recommendation?
John O'hearn 
from Maryland 
June 26, 2013
Answer
They are exactly the same generator except one comes with a transfer switch and the other one is the generator only.

Model 6244 includes the 200A Automatic Transfer Switch.

Model 6250 is the Generator Only.
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What size NG line for 18 kw generator?
Bill 
from New Jersey 
June 13, 2013
Answer
The pipe size is based on the distance the generator is from the fuel source.

***The 18/20kW requirements are:

Natural Gas (NG)-

3/4" - Cannot Use
1" Pipe - Max 20 Feet
1-1/4" Pipe - Max 130 Feet
1-1/2" Pipe - Max 305 Feet

Liquid Propane Vapor (LP) -

3/4" - Max 15 Feet
1" Pipe - Max 115 Feet
1-1/4" Pipe - Max 480 Feet
Note: LP Pipe sizes are using a second stage regulator.

The pipe sizes are measured by inside diameter (ID) to include any fittings, valves (Must be full flow), elbows, tees or angles. Add 2.5 ft. per any bend, tee or angle in the pipe to the overall distance.

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.

Note: Refer to NFPA 54 for NG or NFPA 58 for LP codes.

Note: Required fuel pressure for natural gas is 3.5 to 7 inches of water column and the required fuel pressure for LP Vapor is 10 to 12 inches of water column.
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Have a 100 amp service panel and was recommended to buy a 20kw generator and a 100 amp service entrance rated ATS. My question is which generator brand would you recommend for value, dependability, and service? Many local installers recommend Generac but a couple have told me that Kohler makes a much better unit and has a better warranty. Don't know who to believe so I will trust your judgement! Also if you could recommend the necessary ATS that would be great! Thanks!
Robert Gostl 
from Louisiana 
June 04, 2013
Answer
The new Generac line of home standby systems have been improved greatly and are the top rated generator in the industry today. They also come with the same 5 year warranty that Kohler offers. I would recommend the Generac model 6250 and the RTSY100A3 transfer switch.

Generac RTSY100A3
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I am looking to purchase a 20Kw generac standby generator. I have two 150AMP panels at my home and would like to set up one generator with two automatic transfer switches. Is this possible or should i go with one 400 amp transfer switch instead?
Domenic  
from New York 
May 23, 2013
Answer
I would recommend going with 1 - 300A transfer switch instead of multiple switches for ease of installation and cost.

You would need to purchase the generator and switch separately as they do not package a model with a 300A switch.

Here are the links to each item....

RTSY300A3 Transfer Switch

Generac 6250 - 20kW Generator
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