What Powers a Whole House Generator? Here’s What You Should Know

Home standby generators, also called backup or whole house generators, are permanently wired into your home’s electric panel and automatically turn on during a power outage.

Whole house generators can run on various fuels depending on the model, including natural gas or propane. Natural gas is one of the best and most common fuel sources for a whole house generator. It burns cleanly, is inexpensive, and many homes already have a natural gas line. Those without natural gas will use propane gas, which is provided by an above-ground or under-ground tank.

There are many options when choosing a whole house generator for your home. Let’s look at what precisely a whole house generator is, what powers them, and a few other essential tips regarding their maintenance and care.

What is a Whole House Generator?

Whole house generators are also known as standby generators. Whole house generators are capable of powering an entire house during an outage. Depending on the size of your home, your whole house generator can vary in size and performance. 

Suppose you have a small, one-level home with no central air conditioning or other systems requiring large amounts of electricity to run. In that case, your whole home generator will be smaller than that of a large, multi-level house with an extensive HVAC system.

Whole house generators provide enough power for all the circuits in your home, thus the term “whole house.”

What Fuel do Whole House Generators Use?

Traditionally, most modern house generators run on natural gas or propane. 

For people that live in rural locations, diesel or gasoline-powered generators may be their only option for backup power.

Depending on your location and specific household needs, there are four types of fuel used by whole house generators; natural gas, propane, diesel, and gasoline.

1. Natural Gas

Natural gas is typically in good supply, inexpensive, and burns cleanly. It is the most popular choice for powering a whole house generator for homeowners with a natural gas line running to their house. If you do not have a natural gas line, you will need to choose a different fuel to power your generator.

2. Propane

One of the main advantages of using propane to run your generator is that it will last longer in storage and retain its potency longer than the other heating oils. Propane is easily stored in large tanks and will run a whole house generator for an extended amount of time, depending on your fuel supply.

3. Diesel

Diesel is a viable option for generator fuel if you live in a remote location where you cannot easily access natural gas or propane. Although it does not burn as cleanly as propane or natural gas, diesel does not cause as much mechanical stress as gasoline does on your generator. 

Diesel uses compression heating instead of spark ignition, and therefore It is not a combustible fuel, which makes it a safer option than gasoline.

If you purchase a diesel-run generator from Generac, you may also wish to buy an extended tank, allowing you to store more fuel. The Generac Protector, Diesel series models, come in 30KW and 50KW. You can use both models with a 132 gallon (extended) tank. Their smaller models are 15KW and 20KW, and you can use them with a 95 gallon (extended) tank.

4. Gasoline

You’ll most commonly find portable generators powered by gasoline. If the generator is only needed for a short time to power a couple of small appliances or tools, then a gasoline generator may be a good option. Whole house generators that use gasoline as fuel are not very common. The main advantage of this fuel is that it is easy to find and store. 

The Difference Between a Whole House and Portable Generator

Here are some of the main differences between the two types of generators:

Generator CharacteristicWhole House GeneratorsPortable Generators
PortabilityUsually professionally installed and stationaryPortable, often with wheels
SizeTypically larger and more powerfulGenerally smaller, but there are some large and powerful units
Start-UpConnected to the house and automatically starts during an outageTypically you need to start it when an outage occurs manually
Run TimeHooked up to a fuel line or a large tank that allows a very long run timeTypically runs on a smaller tank that needs refueling every 6-18 hours

Characteristics of Whole House Generators

In most cases, a professional technician will install your whole house generator, and it is a prominent, permanent fixture outside your home. Whole house generators usually have a weatherproof enclosure around them that helps to dampen the motor’s sound to a degree.

Whole house generators typically run on natural gas or propane. When there is a power outage, a transfer switch automatically switches and starts running the generator to power devices and equipment in your home.

You can run things like your furnace, kitchen appliances, television, lights, computers, and sump-pump with a whole house generator.

Natural gas and propane are easy fuels to store in large quantities allowing a whole house generator to run for weeks or maybe even indefinitely if the natural gas supply is interrupted. 

Whole house generators are wired directly into your home’s electrical system and connect directly to the fuel source. If the power goes out, these generators will turn on automatically. This means no trudging outside in terrible weather for the homeowner to restore power to their home. 

Once the house regains power, the generator will automatically turn itself off. Whole house generators are best suited to long-term power outages, and you’ll typically find them in areas that get a lot of storms.

They are the “cream of the crop” regarding backup power during an emergency and are the most recommended generator type for those who can afford to have one installed. Unfortunately, whole house generators are cost-prohibitive for many people, costing anywhere from $1,000 to over $10,000.

Characteristics of Portable Generators

Portable generators are generally smaller and lighter than whole house generators and, therefore, you can easily move them from location to location. 

They are popular in the construction industry as they can power tools on-site and easily move locations and job sites. People with campers also often use generators to run their camping facilities.

Portable generators usually run on gasoline or diesel and tend to be louder and dirtier than whole house generators. It is always advisable to have extra fuel stored safely and adequately to run your portable generator during an emergency.

The operating time of your generator will depend on how large your fuel tank is, how much fuel you have stored in reserve and how many appliances you have connected to the generator.

Portable generators can be used to power your home; however, you will most likely need to prioritize and choose which appliances you wish to run. 

If your generator is the type that can run on natural gas and is large enough, you can power major items such as your furnace. 

Portable generators don’t offer the convenience of an automatic start-up upon a power outage, and they will have to be removed from storage and set up when the power goes out. They will also need regular maintenance and safety inspections each time they are in use. 

In addition to the advantage of portability, these generators are more affordable for the average person. They can range in price from $300 to several thousand dollars. Portable generators are ideal for short power outages and can only power a few appliances simultaneously due to their limited power.

How to Maintain a Whole House Generator

It is best to hire a professional to maintain your whole house generator. Opening your generator and removing parts can be very dangerous and possibly lead to the nullification of your warranty.

Even though you should not perform maintenance on your generator, it is a good idea to read the owner’s manual that came with your unit and become familiar with your generator’s particular repair and maintenance schedule.

A professional should check your unit once every one to two years or after a period of heavy usage. 

Whole house generators are like cars; they need regular oil changes. You should change the oil once every two years or after 200 hours of use. If you have had a period of heavy generator use, call your maintenance professional to check the oil before using your unit again.

Your maintenance professional will also inspect your spark plugs and air filter and replace them if necessary. 

How to Extend the Life of Your Whole House Generator?

If you opt for a whole house generator, here are five things you can do to ensure that it lasts as long as possible.

1. Regular Maintenance

Make sure that you perform regular maintenance on your generator. Something as simple as starting your generator once a week and circulating the oil can be beneficial. 

These weekly “test runs” will give you the chance to inspect and listen for any strange noises or anything else that seems out of place.

Most dealers will provide you with a warranty, or you can purchase an extended warranty that includes maintenance schedules. This will help you identify any costly problems before they occur.

A certified professional will inspect your generator and reassure you that your backup power source is ready for the winter or stormy season. 

2. Regular Cleaning 

Regular cleaning of your generator is another crucial step in making your unit lasts as long as possible. Decrease wear and tear on your generator by ensuring the intake and exhaust fans are free of debris. 

During the winter months, clear snow away from your generator and remove any weeds or vegetation around your unit. 

If you use an enclosure to protect your generator from the elements, check it regularly for any critters that may have decided to set up camp inside. These pesky visitors can cause damage to electrical systems and other parts of your generator if they are left unchecked.  

3. Check Oil Levels

It is always wise to check your oil levels before starting your generator. If your levels are low, be sure to fill to the recommended amount. 

Always use the appropriate oil type for your unit as per the owner’s manual. If you use the wrong kind of oil, this can damage your generator, decreasing its longevity. 

4. Cover Your Generator

Keeping your generator protected from the elements is an excellent way to prolong its life. Place your generator in your garage or shed while it is not in use or consider building or buying an enclosure for your unit. 

Taking care of your generator in this way will add years to its life as it will protect the unit’s components from moisture and unwelcome guests making their home inside.

5. Pay Attention to Warning Signs

When testing or operating your generator, pay close attention to anything out of the ordinary. 

If you notice strange sounds or odors coming from your generator, it is best to turn the unit off immediately. Seek professional help in diagnosing and fixing the issue before continuing to operate your whole house generator.

Final Thoughts

Whole house generators are a wise investment for those looking for backup power during an outage. 

Although they are more expensive than portable generators, whole house generators have an extremely long lifespan and run time, especially ones that run on natural gas as fuel.

Natural gas is a popular choice for powering whole house generators because many houses already have a natural gas line plumbed for their property. Having your generator hooked directly up the preexisting natural gas line is usually pretty straightforward.

If natural gas is not available as a fuel option, whole-home generators can also run on propane, diesel, and, although not very common, gasoline.

Whole house generators are permanent fixtures and require regular inspection and maintenance to ensure that they are in good working order for the next power outage.


Hubert Miles

I've been conducting home inspections since 2002. I'm a licensed Home Inspector, Certified Master Inspector (CMI), and an FHA 203k Consultant. I started PickGenerators.com to help people better understand whole-house and portable generators.

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