Square footage is only a rough start. Real standby sizing comes from the big loads — central AC, electric range or dryer, well/sump pumps, EV charger — and whether you want whole-home coverage or essential circuits. That is what our free load assessment measures at your Wheaton-area address.
Load worksheet (typical running watts — public education sources)
Use these as planning numbers, not a substitute for a load assessment. Starting watts for motors are higher.
| Load | Typical watts (running) | Source |
|---|---|---|
| Central air (≈2.5 ton example) | ~3,500 W | U.S. DOE EERE education PDF “Energy Efficiency in the Home” Standard Appliance Energy Consumption chart (efficiency_energyinhome.pdf) |
| Electric clothes dryer | ~5,000 W | Same DOE chart |
| Refrigerator / freezer (frost-free, compressor on) | ~500 W | Same DOE chart |
| Electric range (cooktop example in chart) | varies; chart lists range loads in the multi-kW range | Same DOE chart — verify nameplate on your appliance |
| Furnace fan motor (intermittent) | ~350 W | Same DOE chart |
| Dishwasher | chart lists dishwasher loads | Same DOE chart — use nameplate |
| Sump / well pump | Nameplate starting + running watts | Read the pump motor plate; do not guess |
| Level 2 EV charger | Circuit amp × voltage (often 30–50A @ 240V) | Charger / breaker nameplate |
Source: U.S. DOE “Energy Efficiency in the Home” (PDF)
Whole-home vs essential circuits
Whole-home standby keeps the main panel online. Essential-circuits setups protect a chosen subset. Our Generac campaign leads whole-home; essentials after assessment if you prefer a smaller unit.
Sump pumps & DuPage basements
Clay soils and spring rains make sump circuits non-negotiable for many Wheaton, Glen Ellyn, and Naperville basements. If the pump is not on the generator, a long outage during a storm is the failure mode that floods finished basements. Confirm the pump circuit in the assessment — see also sump pump services.
Free load assessment
Book your complimentary load assessment. Related: cost guide · Kohler vs Generac · city pages for Wheaton, Naperville, Glen Ellyn.
DFC Mechanical, Inc. DBA OneStop Pro · 805 W Liberty Dr, Wheaton, IL 60187 · 630-733-9000
IL plumbing contractor license 055-044076 · Dan Foss, IL licensed plumber 058-197647
FAQ
Is square footage enough to size a generator?
No. Square footage is a rough start. Real sizing comes from simultaneous big loads — central AC, electric range/dryer, well or sump pumps, EV chargers — and whether you want whole-home or essential circuits only.
What size Generac do I need for a 2,000 sq ft house?
It still depends on the load list, not the floor plan. Two 2,000 sq ft homes with different HVAC and electric appliances can need different kW. Book a free load assessment.
Whole-home vs essential circuits — what’s the difference?
Whole-home covers the panel so life continues nearly normally. Essential-circuits covers a curated subfeed (furnace, fridge, sump, lights, outlets). We lead with whole-home on our Generac campaign; essentials are a secondary option after assessment.
Why do DuPage basements change the sizing conversation?
Sump pumps and basement finishing loads matter after heavy rain. If the sump is on the generator, confirm starting watts and that the circuit is in the covered set.
Do you use Generac’s sizing tools?
We can reference manufacturer tools, but our complimentary in-home load assessment is what produces the written kW recommendation for your address.