Generac 28kW Generator: Specs, Weight, Cost & Buying Guide

Generac 28kW Specifications

Specifications can change by SKU and model generation. Use the exact Generac model number when confirming installation or service details.

How Much Does a Generac 28kW Generator Weigh?

The current Generac 28 kW home standby generator weighs approximately 524 pounds.

Its listed dimensions are approximately:

46.4 inches long × 26.3 inches wide × 30.7 inches high.

That is the generator itself, not necessarily the packaged shipping weight.

For transport, lifting or placement planning, use the shipping information for the exact SKU being supplied.

Generac 28kW Dimensions

The current 28 kW enclosure measures approximately:

46.4 × 26.3 × 30.7 inches

That is roughly:

• 3.87 ft long
• 2.19 ft wide
• 2.56 ft high

These dimensions are the enclosure size, not the complete installation footprint.

The installer still needs to account for:

• Required clearances
• Airflow
• Service access
• Doors and windows
• Fuel connection
• Electrical connection
• Local code

Read the Generac installation guide →

How Much Power Does a Generac 28kW Produce on Natural Gas?

The current Generac 28 kW model is rated at:

25 kW on natural gas

and

28 kW on liquid propane.

That difference matters.

The model name does not mean the unit produces 28 kW on both fuels.

If your home requires more than 25 kW of continuous output while running on natural gas, the 28 kW model may still be too small.

Always size from the fuel-specific rating.

How Many Amps Is a Generac 28kW Generator?

At 240 volts, 28 kW corresponds to approximately:

116.7 amps

The current model uses a 125-amp main line circuit breaker.

Do not use a simple watts-to-amps calculation to design the transfer equipment or wiring.

The complete electrical system should be sized from the manufacturer's specifications and local code.

Is 28kW Enough to Power a Whole House?

For many large homes, yes.

A 28 kW Generac can provide broad or whole-home backup where the home's simultaneous electrical demand fits inside the generator's fuel-specific capacity.

It is especially relevant where the property has:

• Multiple central air conditioners
• Heat pumps
• Well pumps
• Pool or spa equipment
• Electric water heating
• Electric cooking
• Larger motor loads

But 28 kW is not automatically enough for every large home.

A heavily electrified property can still exceed this capacity.

Calculate your generator size →

What Size House Can a Generac 28kW Run?

There is no reliable square-footage rule for a 28 kW generator.

Electrical demand matters more than floor area.

A 4,500-square-foot home with gas heat and gas water heating may require less generator capacity than a smaller all-electric house.

Proper sizing should consider:

• Running load
• Motor starting load
• HVAC
• Electric heating
• Water heating
• Pumps
• Cooking equipment
• Pool equipment
• Other major loads
• Load management

Square footage is useful for rough context only.

Who Is the Generac 28kW Best For?

The 28 kW class is most relevant for homeowners who:

• Need the maximum capacity available in Generac's current air-cooled range
• Are already close to the limit of a 26 kW system
• Have several large simultaneous loads
• Want broad whole-home backup
• Prefer not to move to a larger liquid-cooled platform

It is less compelling if a 22 kW or 26 kW system already covers the house comfortably.

Generac 28kW Fuel Consumption

Fuel consumption changes with electrical load.

The current Generac specifications list approximately:

Natural Gas

• 182 ft³/hr at 50% load
• 297 ft³/hr at 100% load

Liquid Propane

• 2.23 gal/hr at 50% load
• 3.97 gal/hr at 100% load

Actual use can vary with:

• Electrical load
• Fuel pressure
• Ambient conditions
• Generator condition
• Installation

How Much Natural Gas Does a Generac 28kW Use?

At full published load, the current 28 kW model uses approximately:

297 cubic feet of natural gas per hour.

At 50% load:

182 cubic feet per hour.

The gas system must be sized for the generator while also accounting for other gas appliances that may operate during an outage.

That can make gas-meter and pipe capacity an important part of the installation.

How Much Propane Does a Generac 28kW Use?

The current specification lists approximately:

• 2.23 gallons per hour at 50% load
• 3.97 gallons per hour at full load

Runtime depends on:

• Usable propane capacity
• Average electrical load
• Other propane appliances
• Desired reserve

Do not estimate runtime from nominal tank capacity alone.

How Long Will a Generac 28kW Run on a 500-Gallon Propane Tank?

A nominal 500-gallon propane tank is not normally filled with 500 usable gallons.

Actual runtime depends heavily on generator load.

At approximately half load, the current 28 kW uses far less propane than it does at full load.

For realistic outage planning, calculate runtime from:

1. Actual usable fuel.
2. Expected average generator load.
3. Other propane consumption.
4. A reasonable reserve.

What Engine Is in a Generac 28kW?

The current Generac 28 kW uses the Generac G-Force 1000 engine.

The engine has a displacement of approximately 997 cc.

The exact service parts depend on model generation, so use the model number before buying:

• Oil filter
• Air filter
• Spark plugs
• Battery
• Other maintenance parts

What Battery Does a Generac 28kW Use?

The current next-generation 28 kW platform specifies an AGM powersport battery that meets Generac's published requirements.

Do not buy a replacement battery based only on the generator's kW rating.

Confirm the exact model and manual first.

How Loud Is a Generac 28kW?

Generac's current air-cooled 22-28 kW platform uses a sound-attenuated enclosure and reduced-speed exercise technology.

Perceived sound depends on:

• Load
• Distance
• Installation location
• Walls
• Fences
• Hard reflective surfaces
• Landscaping

Compare noise figures only when they are measured using the same test conditions.

Does the Generac 28kW Include a Transfer Switch?

It depends on the SKU.

Generac currently sells both:

• A standalone 28 kW generator
• A 28 kW package with transfer equipment and additional bundled components

Do not compare prices until you know whether both offers contain equivalent hardware.

Check:

• Generator model
• Transfer-switch model
• Transfer-switch amperage
• Service-entrance configuration
• Included accessories

Generac 28kW Installation Requirements

A typical 28 kW installation can require:

• Approved foundation
• Correct generator clearances
• Adequate fuel supply
• Transfer switch
• Electrical connection
• Permits
• Inspection
• Startup and commissioning

The exact requirements depend on the model and local jurisdiction.

Read the Generac installation guide →

Does a Generac 28kW Need a Concrete Pad?

Not necessarily.

Depending on the approved installation method, the generator may use:

• Composite pad
• Concrete
• Properly prepared aggregate base

The foundation needs to remain stable, level and suitable for drainage and service access.

Generac 28kW Natural Gas vs Propane

The current model supports both fuels.

Natural Gas

Maximum published output:

25 kW

Potential advantages include:

• Utility-fed supply
• No on-site fuel storage
• Convenient extended operation where natural gas remains available

Potential installation issues include:

• Gas-meter capacity
• Pipe sizing
• Pressure
• Utility upgrades

Propane

Maximum published output:

28 kW

Potential advantages include:

• Full 28 kW rated capacity
• Stored fuel on the property
• Availability where natural gas is not present

Potential issues include:

• Tank capacity
• Refill logistics
• Runtime
• Regulator and piping requirements

Generac 28kW vs 26kW

The current 28 kW provides only a modest capacity increase over the 26 kW:

On Propane

• 26 kW model: 26 kW
• 28 kW model: 28 kW

Difference:

2 kW

On Natural Gas

• 26 kW model: 24 kW
• 28 kW model: 25 kW

Difference:

1 kW

That makes the 26 vs 28 decision very different from 22 vs 26.

The 28 kW makes sense when that final 1-2 kW genuinely solves the load problem.

If the 26 kW already has comfortable headroom, the 28 kW may offer little practical benefit.

Compare Generac 26kW vs 28kW →

Generac 28kW vs 22kW

Compared with the current 22 kW:

Liquid Propane

• 22 kW: 22 kW
• 28 kW: 28 kW

Difference:

6 kW

Natural Gas

• 22 kW: 21 kW
• 28 kW: 25 kW

Difference:

4 kW

That additional capacity is much more meaningful for houses with several large simultaneous loads.

But the 28 kW should still be justified by a load calculation rather than bought simply because it is the largest air-cooled option.

Can a Generac 28kW Run Two AC Units?

Often, yes.

But exact suitability depends on:

• AC tonnage
• Compressor starting requirements
• Other simultaneous loads
• Soft-start equipment
• Load management

The 28 kW gives more headroom than the 22 kW or 26 kW models, but it does not make load calculation irrelevant.

Can a Generac 28kW Run Three AC Units?

Potentially.

Three smaller or well-managed systems can be easier to support than two very large compressors plus several heavy appliances.

The installer should calculate:

• Running current
• Starting current
• Other loads
• Simultaneous demand
• Load-shedding strategy

Do not size from the number of AC condensers alone.

Load Management With a Generac 28kW

Even at the top of the air-cooled range, load management can still be useful.

A home may contain:

• Multiple HVAC systems
• Electric water heating
• Pool equipment
• Dryer
• Electric cooking

Not all of those loads need to operate simultaneously.

Load management can:

• Prevent overload
• Prioritise critical loads
• Reduce peak generator demand
• Improve system flexibility

Buying the largest air-cooled generator does not mean every circuit should be allowed to start at once.

Is the Generac 28kW Worth It?

The 28 kW is worth considering when:

• 26 kW is genuinely marginal
• The additional 1-2 kW solves a real load problem
• You want to remain on an air-cooled platform
• The installed price difference is acceptable
• The fuel system can support the generator

It is less attractive when:

• 26 kW already has comfortable headroom
• The larger model forces an expensive fuel-system upgrade
• The extra capacity would rarely be used

When I Would Choose the 26kW Instead

I'd stay with the 26 kW when:

• It comfortably covers the calculated load
• Load management handles occasional peaks
• The 28 kW adds no useful capability
• The installed-price gap is meaningful
• Fuel infrastructure is already well matched to the 26 kW

The 28 kW should earn the upgrade.

When I Would Choose the 28kW

I'd choose the 28 kW when:

• The 26 kW sits too close to maximum load
• Natural-gas demand falls between 24 and 25 kW
• Propane demand falls between 26 and 28 kW
• The additional capacity prevents moving into a more expensive system class
• The fuel and electrical infrastructure can support it

When You Need More Than 28kW

The 28 kW is the top of Generac's current air-cooled residential range.

If the calculated load still exceeds its usable capacity, the answer is not to force the 28 kW harder.

Consider:

• More aggressive load management
• Reducing the backed-up load
• Larger liquid-cooled standby systems

This is where system design matters more than simply choosing the biggest air-cooled generator available.

Generac 28kW Maintenance

Routine maintenance can include:

• Engine oil
• Oil filter
• Air filter
• Spark plugs
• Battery
• Inspection
• Exercise-cycle checks

For extended outages, maintenance intervals become especially important because standby generators may accumulate many operating hours quickly.

Follow the manual for the exact model and operating conditions.