If you’re looking into a backup generator for your home, you’re likely doing so with a clear goal: staying safe, comfortable, and connected when the power goes out. But one of the biggest decisions you’ll face is what size generator to install. And no—it’s not one-size-fits-all.
At RB Heating ClimateCare, we regularly help homeowners in Eastern Ontario choose the right standby generator based on their lifestyle, home size, and budget. Below, we break down what you need to know about sizing, including the three most common coverage tiers and what each can power.
Essential Circuits Only: 8–12 kW
If your main concern is keeping the bare essentials running, this size range will give you peace of mind at a lower cost. Generators in the 8–12 kilowatt range are designed to power selected circuits only, which means you’re covered for key functions without energizing the entire home.
Typical coverage includes:
- Gas or oil furnace (or boiler)
- Sump pump and/or sewage ejector
- Refrigerator and freezer
- Microwave or small cooktop
- Lighting in main rooms or hallway
- Modem/router and home office essentials
This size is ideal if your home is on municipal water and sewer, and you’re looking to avoid food spoilage, frozen pipes, and major interruptions. Many homeowners pair this setup with an automatic transfer switch that activates only the priority circuits during an outage.
Mid-Range Coverage: 13–20 kW
This size category is best for households that want more than the basics—especially if you’re working from home or rely on electrically powered heating systems. A 13–20 kW generator can power more circuits simultaneously and may support a small-to-medium home without issue.
You can expect it to power:
- All essentials listed above
- Electric baseboards
- Washer and dryer
- Garage door opener
- Well pump (if not on municipal water)
- Larger kitchen appliances like stove or dishwasher
- Dedicated circuits for a home office, entertainment system, or hobby space
If you live in a rural area where outages are longer or more frequent, or if you run your household largely on electricity, this size offers added security and comfort without moving into whole-home territory.
Whole-Home Coverage: 20 kW and Up
Looking for full coverage without compromise? Generators 20 kW and larger can power everything in your home, just as if the grid were still running. These are ideal for larger homes, families with medical equipment, or homeowners with multiple HVAC systems, heated garages, or home automation networks.
Typical whole-home usage includes:
- Heating and cooling (central AC, heat pump, or electric furnace)
- Well pump and water treatment systems
- Washer, dryer, dishwasher, and full kitchen
- Lighting and outlets in all rooms
- Electric vehicle chargers
- Smart home hubs, security systems, and Wi-Fi
- Detached garage or outbuilding circuits
Whole-home systems offer the most seamless experience, automatically taking over when the power goes out and covering every room. While they come with higher upfront costs, many homeowners see it as a long-term investment in comfort and property value, especially in areas prone to long outages.
How to Choose the Right Size for Your Home
Choosing the right backup generator size isn’t about square footage—it’s about how your household functions on a daily basis and what you can’t afford to lose during a power outage.
Here’s what to consider:
- Do you rely on a well or septic system?
- Is your heating system electric, gas, or oil-fired?
- Do you work from home or run a business from your property?
- Is medical equipment part of your household?
- Are you in a rural area where outages last longer?
At RB Heating ClimateCare, we help you assess these details so your generator works exactly how you expect it to when you need it most.
We’re Here to Talk About Generator Sizing
RB Heating ClimateCare can help you choose and install a generator that fits your home and your lifestyle. Contact us today to schedule a free consultation and find the right backup generator size for your home. We proudly serve homeowners in Brockville, Prescott, and surrounding areas.
