How to Size a Backup Generator for Your Central Texas Home
Why Generator Sizing Matters
One of the biggest mistakes homeowners make when buying a generator is choosing a unit that’s too small. Dealers often sell undersized systems to keep the sticker price low — but when the power actually goes out, the generator can’t handle the load. That means the lights may come on, but your HVAC or major appliances won’t run.
At Weatherproof Generators, we size systems correctly the first time so your home stays fully powered during a storm or freeze.
The 70% Load Rule
A generator’s rating (in kilowatts, or kW) doesn’t tell the whole story. For safe operation, electricians recommend not exceeding 70% of the unit’s total capacity.
Here’s why:
Running a generator at 100% overloads the system.
Continuous overload shortens lifespan and risks failure during an outage.
Staying under 70% ensures reliable performance when you need it most.
Example:
A 14 kW generator × 70% = 9.8 kW usable power.
At 240 volts, that’s ~40 amps.
40 amps isn’t enough to run a full HVAC system plus lights and appliances in most homes.
Quick Sizing Guide for Central Texas Homes
Load Profile: Essentials Only
Recommended Generator Size: 14–16 kW
Typical Loads Covered: Refrigerator, lights, TV, plus one portable AC or mini-split,
Load Profile: Typical Whole-Home
Recommended Generator Size: 18–22 kW
Typical Loads Covered: One central HVAC, fridge, lighting, outlets, Wi-Fi, microwave,
Load Profile: High-Demand Whole-Home
Recommended Generator Size: 24 kW+
Typical Loads Covered: 2+ HVACs, pool equipment, well pump, EV charger, electric range,
Common Undersizing Mistakes
One HVAC unit only: Dealers size for a single system, not your whole home.
Ignoring startup loads: Appliances draw more power when turning on than when running.
Selling on price: A “cheaper” unit that doesn’t power what you need, ends up being wasted money.
Why Correct Sizing Saves You Money
Fewer repairs: Properly sized units don’t burn out under strain.
Lower risk: No outages during freezes or storms because the unit can’t handle demand.
Better resale: A right-sized system adds value to your home.
Our Approach
When you work with Weatherproof Generators:
We calculate your actual load needs.
Both licensed electricians and plumbers size, install, and connect your system.
We guarantee a code-compliant installation with a 100% passed inspection rate.
Ready to Find the Right Size for Your Home?
Don’t let a dealer sell you a system that’s too small. Get expert sizing and installation from licensed professionals who guarantee results.
Want to know what a right-sized system costs? Check out our Generator Installation Costs in Central Texas (2025 Guide).