Residential Generator FAQs

You have questions about Home Generators.
Derr has answers.

You have questions about Home Generators.
Derr has answers.


The size generator that is right for your home depends on your power needs. One call to Derr Heating truly ”Does it all.”  We will analyze your home’s electrical load, estimate, specify and install your generator system.

A home visit may not be necessarily provide an estimate, but the requirements and  installation process can vary from home to home. Factors that impact installation cost include:

• Your desired fuel source and whether you already have it running to your home
• Any local permits that are required for installation.
• The location your generator will be installed at on your property
Because of the different factors that impact installation costs, we prefer not to give a complete quote without doing an evaluation of your home’s layout to determine where and how the generator will need to be installed. 

KOHLER Residential Generators, including the engines, are designed and assembled in America.  KOHLER sources components and parts from trusted suppliers all over the world, including many here in the USA.

Please see our Pre-Approved Financing page at for information on obtaining financing for your Whole House Home Generator.

Our generators connect seamlessly to your home’s natural gas or liquid propane system. If you do not currently have natural gas service, you may have a liquid propane tank installed on your property for your generator.

Our generators are built to perform in all weather conditions, from hurricanes to blizzards. To ensure your generator functions properly, we may recommend the use of cold-weather accessories where temperatures fall or stay below 32 degrees Fahrenheit. The best way to determine the accessories that would be most beneficial for you is to speak with your Derr advisor.

Yes! Many solar energy systems can be backed up by KOHLER generators. Whether you are looking to charge a battery bank or back up the home when solar energy alone is not sufficient, Derr can advise you on the best KOHLER solution for your situation.

RESAL generators come with a transfer switch. RESA generators come with a controller that offers access to advanced settings; a transfer switch is purchased separately.

Because a standby generator is routed into your home’s gas and electrical system, installing a standby generator is a job for a trained professional like an authorized Kohler dealer. The professionals at Derr Heating and Cooling are able to  ensure a safe installation, navigate local codes, and provide any necessary upgrades to your home’s gas or electric systems. 

Yes! Standby generators are used to provide backup power to mobile homes across the country.

Since standby generators are permanently installed outside of your residence, we do not recommend them for apartments that you do not own. Our generators may be installed in townhomes if there is ample space to install it and your community allows it. 
We recommend first consulting your property manager to ensure standby generator installation falls within their bylaws. If so, we can determine whether your townhome has adequate space for installation.

 Code requirements for installing standby generator systems vary nationwide. That’s why Derr recommends having us nstall your system, since we will be familiar with both local and national codes and permits.

Generators ship without batteries to ensure that the freshest possible battery is installed at the jobsite. Your Operation Manual recommends the proper battery for your generator model. Batteries come in sizes that are readily available at any battery or auto-parts store.

 It’s a good idea to have Derr Heating perform an onsite analysis to determine which generator and transfer switch offer the best solution for your home.

A service-entry-rated switch comes equipped with a main-line disconnect breaker built into the transfer switch. This is a nationwide code requirement when the transfer switch is wired directly into the incoming main power line for whole-house power. A non-service-entry-rated switch requires the addition of a disconnect breaker at the jobsite. The service-entry-rated switch saves you time and money during the installation process.

RESAL generators come with a transfer switch. RESA generators come with a controller that offers access to advanced settings; a transfer switch is purchased separately.


KOHLER OnCue® Plus is a remote monitoring and generator management app available for download in the Apple App Store and the Google Play Store. The app is free and is compatible with both phones and tablets.

With the KOHLER OnCue® Plus Generator Management System, you can check the status of your generator, start or stop an exercise, check the oil temperature, contact your dealer, and so much more. And with the OnCue Plus Skill on Amazon Alexa or OnCue Plus Action on Google Assistant, you can control your generator or get status updates using just your voice. 


Open the generator hood or access door and flip the circuit breaker to the “off” position (you’ll find the breaker near the digital controller). This shuts off power to the house (the load). It’s a good idea to run the generator with no load for 2-5 minutes. Then press the “off” button on the controller.

A large metal key is included in your owner’s packet. Insert and turn the key 45 degrees to open the top hood or side-access door of the generator.

Water and electricity are a very dangerous mix. If you can safely access it, power off the generator. If it continues to run when submerged, internal damage to both engine and generator will be significant. If you can’t safely access the generator or the main-line disconnect, do not make any attempt to turn it off.

We recommend checking the oil level after every 8-24 hours of operation, depending on the size and model of the generator. Oil change and filter change frequency and other routine maintenance varies per model, especially during periods of extended power outage. The Operation Manual included with your generator has a complete list of required maintenance procedures and schedules.
1. Power off the generator and let the engine sit for two minutes to settle the oil. Pull the dipstick from the back of the engine and wipe with a clean rag. Insert the dipstick back into the dipstick tube and pull it out. Note the cross hatching on the end of the dipstick, from “F” (Full) to “L” (Low), and see where the oil level falls. Add oil if the dipstick indicates that the oil level is low. 

 2. Locate the yellow oil-access cap on the front of the engine (look for the oil can icon). Add a few ounces of oil, then recheck the oil level by inserting and removing the dipstick. Add oil until the level is near “F.” Do not overfill the engine.

 3. When you’re finished adding oil, make sure the dipstick and oil access cap are securely in place. Push the AUTO button to place the generator back in standby mode. If the utility power is still out, the generator will start within three seconds. After the generator starts, move the circuit breaker to the ON position so the generator is now supplying power to the house.

The dipstick has a bright yellow ring attached to the end. The location varies by generator, but it’s typically noticeable as soon as you open the access panel or hood.

Your KOHLER generator ships with KOHLER Genuine Oil 5W-30 full-synthetic oil, which is the oil Kohler recommends. Although a synthetic blend may be used, our recommendation is full-synthetic oil. However, if you know that the oil has been changed out to conventional oil, then use only conventional oil from that point on. Do not mix synthetic oil with conventional oil.

The amount varies and depends on the engine model, length of time since the last oil change, amount of power the generator is producing and length of the power outage. Check the Operation Manual included with your generator for a complete list of required maintenance procedures and schedules.


Yes, your KOHLER standby generator will be covered by a 5 year/2,000 operating hour warranty. You may also upgrade to our extended warranty, which covers parts, labor and dealer for 10 years.

To register your warranty, your Derr service technician will complete a post-installation Warranty Start-Up at your home. Then, instead of your warranty beginning on the day the generator is purchased, it begins on the day our service technician submits your generator system’s details to the Warranty Start-Up program. Our service technician will complete a checklist, make sure the system is properly installed, and enter all necessary information onto the Kohler Warranty site. This moves the warranty start date to the day your generator is installed, instead of the date it left the factory.

**Warranty conditions only apply to North America.