Bent Mountain, VA Standby Generator Installation & Maintenance Guide

Estimated Read Time: 9 minutes

When storms roll through Roanoke and the Blue Ridge, outages happen fast. Choosing the right whole house generator size avoids tripped breakers, fuel waste, and buyer’s regret. In this guide, we show you how to size a whole house generator the smart way, from must-run loads to transfer switches, so your family stays comfortable and safe. Want a shortcut? Use the worksheet below and we’ll double-check it during your free quote.

What “Right Size” Really Means

Buying too small means brownouts when your heat pump or well pump kicks on. Buying too large burns fuel and budget. The right size matches your home’s starting and running loads, fuel supply, and transfer switch rating, all while meeting code. In Southwest Virginia, we also plan for cold-start amperage on heat pumps and well systems common around Hardy, Goodview, and Wirtz.

Key goals:

• Power the circuits you care about every day, not just lights
• Handle motor starting surge without voltage drop
• Fit your fuel and transfer switch capacity
• Comply with NEC Article 702 for optional standby systems

Step 1: List Your Must-Run and Nice-to-Have Loads

Start with the essentials for comfort, safety, and work.

Must-run examples:

• Refrigerator and freezer
• Sump pump or well pump
• Heating system or heat pump air handler
• Wi-Fi, home office, key outlets
• Select lighting circuits and the kitchen microwave

Nice-to-haves:

• Electric oven or range
• Clothes dryer
• Garage door opener and EV charger (often curtailed)

Tip: In older Salem and Vinton homes, shared lighting and outlet circuits can complicate selection. Mapping your panel avoids surprises on install day.

Step 2: Calculate Running Watts and Starting Surge

Every appliance lists amps or watts. Use this rule of thumb:

Watts = Volts × Amps Motor loads can demand 2–3× running watts at startup

Typical ranges:

• Refrigerator: 150–300W running, up to 1,200W start
• Sump or well pump: 700–1,500W running, 2,000–4,000W start
• Gas furnace blower or air handler: 400–800W running, 1,200–1,600W start
• Heat pump compressor (tonnage varies): 1,500–3,500W running, 3,000–7,000W start

Add up running watts for all must-run items, then add the largest single starting surge on top. This gives you a realistic minimum size.

Step 3: Decide Whole-Home vs. Managed Circuits

Two practical paths:

• Whole-home generator with an ATS sized for your service (commonly 200A). This backs up nearly everything and lets the generator’s controller shed big loads as needed.
• Load-managed or essential-circuits approach using a smaller generator and a smart load shed module to pause EV charging, electric ovens, or secondary HVAC until capacity frees up.

Many Martinsville and Rocky Mount homeowners choose the second option to reduce install cost while keeping comfort.

Step 4: Match the Transfer Switch to Your Electrical Service

Your automatic transfer switch is the traffic cop between utility and generator. It must be listed, sized, and installed correctly.

• Service-rated ATS should match main service size, often 200A in modern homes
• Non-service-rated ATS can be used with certain panel configurations; we will advise
• NEC Article 702 requires that optional standby systems prevent backfeed and follow manufacturer instructions

If you have a 200A service in Cave Spring or Roanoke, a 200A ATS is the common fit. Some homes with 400A services use dual ATS units or service-rated solutions with load management.

Step 5: Choose Your Fuel and Plan for Run Time

Fuel availability influences generator size and operating cost.

• Natural gas: Unlimited supply if you have service. We check meter capacity and gas line sizing for combined winter loads.
• Propane: Plan tank size for multi-day outages. A 250–500 gallon tank is common for residential standby systems.

Right-sizing means matching expected load with a fuel plan. Oversizing a generator can increase fuel burn per hour, which matters during multi-day Appalachian Power outages.

Step 6: Pick a Realistic Size Range

Based on thousands of home assessments, these ranges cover most scenarios:

• 9–12 kW: Essential loads, gas heat, one small air handler, well pump or sump
• 13–18 kW: Most 2–3 bedroom homes, heat pump with soft start or staged management
• 20–26 kW: Larger homes, multiple air handlers, electric water heater, and more whole-home comfort

Every home is different. Equipment age, motor inrush, and panel configuration in places like Wirtz and Goodview can shift the choice up or down.

Quick Home Sizing Worksheet

Grab your panel schedule and run these steps:

1. Circle must-run circuits: fridge, heating, water, key receptacles, office, lighting
2. Write running watts for each using equipment nameplates or manuals
3. Identify the largest motor load and its starting watts
4. Add all running watts, then add the largest starting surge
5. Decide on whole-home or managed loads and note shed items
6. Compare your total to 9–12 kW, 13–18 kW, and 20–26 kW ranges

Bring this sheet to your free quote. We will verify with meter readings and manufacturer data.

Cold Weather and Heat Pump Considerations

Heat pumps in the Roanoke Valley often use auxiliary heat strips in freezing weather. Those strips can add 5–10 kW.

Two smart options:

• Use load management to temporarily disable heat strips during startup
• Add manufacturer-approved soft-start kits to reduce inrush

These steps maintain comfort without oversizing your generator.

Well, Sump, and Septic Pumps

Pumps draw short but heavy starting surges. In Collinsville and Hardy, many homes rely on wells.

To size correctly:

• Confirm horsepower on pump tags
• Assume 2–3× running watts for starting
• Consider staggered starts using load management if multiple pumps may start

Transfer Switch Types Explained

Two common ATS styles:

• Service-rated: Includes a main disconnect and may become the service entrance
• Non-service-rated: Installed downstream of the main, depending on layout

Both must be UL-listed and installed per code. A 200A ATS pairs well with many Kohler whole-home systems used around Roanoke. Correct switch selection protects linemen, your equipment, and your warranty.

Noise, Placement, and Setbacks

Most standby generators sit on an outdoor composite pad. For safety and compliance:

• Follow manufacturer clearances from doors, windows, and vents
• Keep exhaust away from living spaces
• Observe zoning setbacks and HOA rules

We review placement during your estimate to prevent noise reflection and airflow issues.

Maintenance Affects Sizing and Longevity

A properly sized generator runs more efficiently and lasts longer. With routine maintenance, many units reach 15–20 years, compared to an average of 8–10 years.

Plan for:

• Oil and filter changes
• Air filter and spark plug replacement
• Exercise runs and load testing
• Annual electrical inspection of conductors, lugs, and ATS contacts

Our Diamond Club members receive priority service, discounted repairs, and annual electrical inspections.

Compliance, Safety, and Real-World Loads

True sizing respects both code and real-life use. We design to NEC Article 702, manufacturer specifications, and local utility requirements, accounting for:

• Voltage drop during motor starts
• Sensitive electronics and harmonics
• Gas meter and regulator capacity

This approach prevents nuisance trips and extends equipment life.

Budgeting and Financing Considerations

Larger kW systems increase equipment, ATS, and wiring costs. You can often save by:

• Choosing managed loads instead of full whole-home backup
• Adding soft-start kits where approved
• Scheduling installations outside peak storm months

Financing through GoodLeap, including 0% no-interest periods on select jobs, helps spread costs.

Local Insight: Roanoke and Surrounding Areas

Appalachian Power outages spike during summer storms and winter ice. Homes in Roanoke, Salem, and Vinton often have 200A services and mixed gas-electric systems. Around Rocky Mount and Wirtz, wells and detached shops are common. We factor all of this into sizing and layout decisions.

When to Consider a Larger Unit

Size up if:

• You have multiple HVAC systems or mini-splits
• You cook on electric and want normal operation during outages
• You plan to add a hot tub, workshop tools, or an EV charger

Planning ahead avoids buying twice.

What Happens During Your Free Quote

We verify panel details, measure loads, confirm gas capacity, and recommend the appropriate ATS. You receive a clear written proposal with options. After installation, we test every protected circuit and provide clear operation and maintenance instructions.

Post-Install Care and Ownership

To keep your system ready:

• Allow weekly exercise runs to complete
• Keep snow, leaves, and debris clear
• Schedule annual service and firmware updates

Our team provides 24/7 support when storms hit nights or weekends.

Special Offer

Free Quote for Generator Installation and Services in Roanoke Call (540) 426-1351 or schedule at https://callwisler.com

What Homeowners Are Saying

“Roger was professional, very knowledgeable, and a pleasure to work with during our generator estimate. He took the time to explain options and differences between models. We would definitely recommend Wisler to anyone wanting quality service and great technicians.” – Ron N., Generator Estimate

“I had been thinking about getting a whole-house gas generator for years. Wisler’s job estimator, Roger Custer, was easy to talk with and answered all my questions without pressure. I look forward to feeling more power-secure soon.” – Steven S., Whole-House Generator

Frequently Asked Questions

How many kilowatts do I need for a whole house generator? Most homes fall between 13–26 kW. We confirm sizing during your on-site quote.

Do I need a 200-amp transfer switch? If your service is 200A, a 200A service-rated ATS is common.

Can a generator run my heat pump in winter? Yes, with proper sizing and load management.

What fuel is best, natural gas or propane? Natural gas offers continuous supply; propane works well with proper tank sizing.

How long will a home generator last? Average lifespan is 8–10 years, with many reaching 15–20 years with maintenance.

Wrap-Up

Sizing a whole house generator means matching real loads, fuel, and transfer equipment to your goals. With code-compliant design and routine care, your system will protect your home for years. If you need help determining the right whole house generator size in Roanoke or nearby, we are ready to help.

Ready to Get Your Size Right?

Call Wisler Plumbing, Heating, Cooling & Electric at (540) 426-1351 or schedule at https://callwisler.com. Ask for your Free Quote for Generator Installation and Services in Roanoke.

Serving Roanoke, Cave Spring, Salem, Martinsville, Vinton, Hardy, Rocky Mount, Wirtz, and Goodview. 24/7 emergency support. Financing available, including 0% no-interest periods on select jobs.

About Wisler Plumbing, Heating, Cooling & Electric

For 40 years, we have protected Southwest Virginia homes with licensed, background-checked, and continuously trained technicians. We follow NEC Article 702 for optional standby systems, back our work with a 100% Satisfaction Guarantee, and provide 24/7 emergency support. Financing options through GoodLeap help make projects affordable. Awards include Virginia Business Best Places to Work 2024 and Angi Super Service Award 2022. Local expertise. Straight talk. Code-compliant installations.