Why Generator Sizing Matters
Choosing the right generator size is the most important decision you'll make in the buying process. An undersized generator will overload and shut down when you need it most. An oversized one wastes money on purchase price and fuel. This guide walks you through exactly how to size a standby generator for your Central New York home.
Step 1: Decide What You Need to Power
Start by answering one question: do you want to power your essential circuits only, or your whole home?
- Essential circuits (furnace, refrigerator, lights, sump pump, well pump, a few outlets): typically 7–14 kW
- Whole-home coverage (everything above plus HVAC, electric water heater, EV charger, etc.): typically 20–22 kW or higher
Most Central NY homeowners opt for a 20 kW or 22 kW air-cooled standby generator, which handles the whole home comfortably without requiring a liquid-cooled commercial unit.
Step 2: Add Up Your Critical Loads
List the appliances you can't live without during a winter outage — this is especially important in Upstate New York where temperatures can drop well below freezing. Common critical loads and their approximate wattage:
- Natural gas or propane furnace blower: 600–1,200W
- Refrigerator: 150–400W running (800W startup surge)
- Sump pump: 800–1,500W running (2,000W+ surge)
- Well pump (1 HP): 750W running (2,500W surge)
- Central air conditioner (3-ton): 3,500W running (8,000W+ surge)
- Electric water heater: 4,000–5,500W
- Lighting and general outlets: 1,000–2,000W
Key tip: Always account for motor startup surge — this is 2–3× the running wattage and is the reason undersized generators fail. Your generator's rated kW must handle the peak surge of your largest motor (usually the A/C or well pump) plus the running load of everything else.
Step 3: Match Load to Generator Size
Here's a quick reference for common home sizes in Central NY:
- 1,000–1,500 sq ft home, gas heat, city water: 10–14 kW
- 1,500–2,500 sq ft home, gas heat, well water: 16–20 kW
- 2,500–3,500 sq ft home, central A/C, well water: 20–22 kW
- 3,500+ sq ft or electric heat/water: 22–36 kW or liquid-cooled commercial unit
Step 4: Account for Fuel Type
Air-cooled standby generators run on natural gas or propane. If you have natural gas service, your generator will be piped directly to it — no tank to fill. Propane-powered generators require an adequate tank (typically 500–1,000 gallons for whole-home use). Diesel standby generators are used primarily for commercial applications. Browse our Air-Cooled Home Standby Generators to see available sizes and fuel options.
Step 5: Don't Forget the Transfer Switch
Every standby generator requires a transfer switch — it's not optional. The transfer switch safely disconnects your home from utility power before the generator comes on, preventing dangerous backfeed onto the grid. Automatic standby generators use an automatic transfer switch (ATS) that detects an outage and starts the generator within seconds — no action required from you. See our Transfer Switches collection for compatible options.
Get a Free Sizing Recommendation
Not sure which size is right for your home? Syracuse Generators serves Counties throughout Central New York, including Onondaga, Oswego, Cayuga, Madison, and surrounding areas. Contact us for a free sizing consultation — we'll walk through your home's load requirements and recommend the right system for your budget and needs.