A permanent whole-home standby generator in Wheaton is a five-part project: a load assessment to size the unit, a site that meets Generac’s clearance rules, a City of Wheaton permit, a gas line sized for the generator, and an automatic transfer switch installed by a licensed electrician. OneStop Pro handles every step from our shop at 805 W Liberty Dr. That includes the permit and the inspection. Once permits are ready, the on-site install is typically 1–2 days. Start with a free whole-home load assessment or call 630-733-9000.
This guide explains what happens at each step, what you can decide ahead of time, and the questions Wheaton homeowners ask us most often.
Step 1: Load assessment (sizing the generator)
Square footage is only a starting point. What sets the size of a standby generator is the set of large loads that may run at the same time: central air, a gas or electric furnace blower, an electric range or dryer, a well or sump pump, and an EV charger. On a load assessment we walk the lot, open the panel, and list those loads. Then you choose between two setups:
- Whole-home coverage: the generator backs up the main panel, so the house runs close to normal during an outage. This is what we recommend first.
- Essential circuits: a smaller unit carries a chosen list, such as furnace, sump, refrigerator, some lights and outlets.
In many Wheaton basements the sump pump is the circuit that matters most. A storm outage with no sump power is how finished basements flood. See sump pump services if your pump or backup is already marginal.
Step 2: Picking a spot that meets clearance rules
Where the unit sits is set by the manufacturer’s instructions and local code, not just by looks. Generac’s site-selection instructions (Part No. A0001446325) call for:
- At least 3 ft of clearance at the front and ends, and 18 in at the rear, including shrubs and trees.
- At least 5 ft of open space above the unit and its clearance zones (no low decks or overhangs).
- Windows, doors, vents and other openings no closer than locally adopted codes allow. NFPA 37 uses a 5 ft baseline.
Generac’s 10–26 kW owner’s manual adds that mechanical or gravity outdoor air intakes must be at least 10 ft horizontally from the enclosure. It also says the unit should sit on high ground, with downspouts, sprinklers and sump discharges aimed away from it. We plan placement around all of these, plus your gas meter, your panel location and any HOA screening rules.
Step 3: City of Wheaton permit and inspection
A permanent standby generator in Wheaton needs City approval. Setbacks from lot lines, openings and air intakes matter, and so does clear access for service. We prepare the drawings, pull the permit, and meet the inspector, and that coordination is in the written price rather than added later. If your subdivision has an HOA, get its approval in writing before the pad goes in.
Step 4: Gas line
Most Wheaton standby generators run on natural gas, and some homes use propane. The gas line has to be sized for the generator’s demand on top of your furnace, water heater and other gas appliances. Undersized piping can make a unit struggle under load. Gas-side work runs under our plumbing licenses (055-044076 / 058-197647), and pipe sizing is part of the written plan from Step 1.
Step 5: Transfer switch and electrical tie-in
The automatic transfer switch (ATS) is what makes a standby generator automatic and safe. When utility power drops, it disconnects your house from the ComEd lines, starts the generator, and moves your circuits over. When utility power returns, it switches back. Generac’s owner’s manual is explicit: never connect a generator to a building’s electrical system unless a licensed electrician has installed an approved transfer switch, because electrical backfeed can kill utility workers and damage equipment.
Older homes near downtown Wheaton and the historic district sometimes still have undersized services or original panels. Those may need an electric panel upgrade evaluation before a transfer switch goes in. Newer homes usually have 200-amp service but larger loads (two HVAC systems, an EV circuit), which changes the sizing.
Install day, startup and owner walkthrough
- Pad set and generator placed per the approved plan.
- Gas piping connected and leak-tested.
- Transfer switch and electrical tie-in completed.
- Inspection, startup, and a simulated outage to confirm transfer.
- Owner walkthrough: what the green, red and yellow status lights mean, how the exercise timer works, and Generac warranty registration support.
Generac units run a short self-test (“exercise”) on a schedule you can set to weekly, every two weeks, or monthly. Generac notes the timer does not adjust for Daylight Saving Time on its own, so we show you how to check it.
What it costs
Price depends on the unit size, how far the gas and electrical runs are, the pad and site work, and permit requirements. We do not quote from a chart. After the assessment you get a written whole-home plan with an upfront price before anything is ordered. Financing is available on approved credit. See the whole-home generator installation page for current offers.
After the install: keeping it ready
A standby generator needs scheduled service: oil, filters, plugs and a battery check on Generac’s Schedule A and Schedule B intervals. Between visits there are simple owner checks. Use our generator maintenance checklist for Wheaton homeowners, and book professional generator maintenance when the yellow maintenance light comes on.
Get your Wheaton load assessment
OneStop Pro is an authorized Generac dealer and has been a family-owned Wheaton company since 2007. Book your free whole-home load assessment or call 630-733-9000. Related: Wheaton generator installation · Naperville · Glen Ellyn · all generator services · power outage safety guide.
Sources: Generac Instruction Sheet, Site Selection, Part No. A0001446325 Rev. D (clearances); Generac Owner’s Manual, 60 Hz Air-Cooled Generators 10–26 kW, Part No. A0001846499 Rev. C (air-intake distance, siting, transfer-switch warning, exercise timer). Always follow the manual for your specific model.
DFC Mechanical, Inc. DBA OneStop Pro · 805 W Liberty Dr, Wheaton, IL 60187 · 630-733-9000
Family-owned since 2007 · IL plumbing contractor license 055-044076 · Dan Foss, IL licensed plumber 058-197647 · Electrical work under ECC-94505 where that credential applies
Frequently asked questions
Do I need a permit to install a whole-home generator in Wheaton?
Yes. A permanent standby generator needs City of Wheaton approval, and setbacks from lot lines, openings and air intakes apply. OneStop Pro prepares the plan, pulls the permit and meets the inspector as part of the project.
How close to my house can a standby generator go?
Generac’s site-selection instructions call for at least 18 inches at the rear and 3 feet at the front and ends, 5 feet of open space overhead, and openings such as windows and doors no closer than local code allows. NFPA 37 uses a 5-foot baseline. Outdoor air intakes need at least 10 feet horizontally per Generac’s 10–26 kW manual.
How long does a whole-home generator installation take?
The on-site install is typically 1–2 days once the permit and materials are ready. The overall timeline depends on City permit review, HOA approval if you have one, and equipment availability.
Can I connect a generator to my panel without a transfer switch?
No. Generac’s manual warns never to connect a generator to a building’s electrical system unless a licensed electrician has installed an approved transfer switch. Backfeed can injure or kill utility line workers and damage equipment.
What size generator does my Wheaton home need?
It depends on which large loads (central AC, furnace blower, electric range or dryer, sump or well pump, EV charger) may run at the same time, and whether you want whole-home or essential-circuit coverage. A free load assessment measures this at your address.