Fort Collins Backup Generator Sizing: 22kW vs 26kW vs 32kW

How Sizing Actually Works

Backup generator sizing is a load calculation, and that is a different exercise than reading a square-footage chart in a brochure. Your total connected load is the sum of everything that can ask the generator for power at the same moment: the HVAC compressor and blower, the electric oven, the electric water heater if you have one, electric resistance heat if your home uses it, pool or spa equipment, well pumps, and the steady background draw of lighting, refrigeration, and small appliances. Each of those has a running watt figure and, for anything with a motor, a much larger starting watt surge. The generator has to absorb the worst realistic combination of those numbers without dropping voltage or stalling.

The peak you are sizing for almost always lands in the morning. That is when the furnace blower or A/C compressor kicks on, the water heater recovers from overnight use, the oven preheats for breakfast, and the coffee maker, toaster, and microwave all run inside a five-minute window. A generator that looks comfortable on paper at average load can still brown out at that peak if the starting surge from the A/C compressor lands on top of everything else. This is why we measure your actual panel and appliances instead of guessing from the listing photos.

There is also a meaningful difference between a managed and an unmanaged install. With a smart load management module and an automatic transfer switch, the system can shed lower-priority circuits for a few seconds while a big motor spins up, which lets a smaller generator cover a home that would otherwise need the next size up. Isaac has spent years on federal power system upgrades where shedding and prioritization were the entire job, and that same discipline is what keeps Fort Collins homeowners from buying more generator than they need.

22 kW: The Standard

The Generac 22 kW, along with its near-equivalents the Kohler 24RCA and the Cummins QuietConnect 22, is the volume choice across Fort Collins for good reason. It comfortably backs a typical 3,000 to 3,500 sq ft home running central A/C, an electric oven, a gas water heater, a gas furnace with its blower, and the usual lighting and outlet loads. For the majority of homes in neighborhoods like Old Town, Harmony, and Fossil Lake Ranch, this is the size that lines up with how the house actually draws power on a cold January morning.

Where the 22 kW starts to feel tight is the moment you add a second air handler, swap the gas water heater for electric, or bring a hot tub online. Any one of those can be absorbed with load management, but stacking two of them is the signal to look at 26 kW instead. Installed cost is a low five-figure job for the Generac and a step higher for the Kohler or Cummins equivalents, with the spread driven by transfer switch type, gas line length, and pad and conduit work.

For most Fort Collins homeowners, the 22 kW hits the value sweet spot: enough headroom to ride out a multi-day winter outage without rationing power, but no wasted capacity sitting idle on the side of the house. When we run the numbers and the answer comes back 22 kW, that is usually the easiest recommendation to make.

26 kW: When to Step Up

The Generac 26 kW, Kohler 26RCAL, and Cummins QuietConnect 26 are the right call when the home pushes past what the standard unit handles cleanly. That covers 3,500 to 5,000 sq ft houses, homes that heat with electric instead of gas, properties with a hot tub or an in-ground pool, and any home running two separate A/C zones. The jump from 22 to 26 kW is not about square footage alone; it is about how many large simultaneous loads you are asking the unit to carry through the morning peak.

Electric heat is the most common reason a Fort Collins home outgrows the 22 kW. Resistance heat is a steady, heavy, continuous draw, and unlike a gas furnace it cannot lean on the gas meter for the actual heating energy. A two-zone cooling setup is the second most common trigger, since both compressors can demand their starting surge within seconds of each other on a hot afternoon. The 26 kW gives you the margin to run those loads without leaning hard on load shedding every cycle.

Installed cost is a low five-figure job for the Generac and higher for the Kohler or Cummins versions. The extra spend over a 22 kW is real, so we only recommend it when the load calculation genuinely calls for it. If your home sits right at the boundary, we will show you exactly which loads are pushing you up and whether load management can hold you at the smaller unit.

32 kW: Large Homes and High-Demand

The Generac 32 kW and the Cummins QuietConnect 32 are built for homes that simply ask more of a standby system. That includes 5,000-plus sq ft properties, homes combining electric heat with an electric range and a pool, residences with home-office or shop loads approaching three-phase territory, and homeowners who want to keep an EV charger running during an outage rather than parking the car for the duration.

The EV consideration is worth calling out, because a Level 2 charger can pull 7 to 11 kW on its own. On a 22 or 26 kW unit, charging during an outage means shedding most of the rest of the house. On a 32 kW, you can keep the home comfortable and still put miles back on the vehicle, which matters when a winter storm knocks power out for two or three days and the roads finally clear. Large homes with multiple heat zones see a similar benefit: the 32 kW carries everything without aggressive shedding.

Installed cost tops the residential range for the Generac and higher still for the Cummins. This is the right tool for genuinely demanding homes, but it is the wrong tool for an average house bought on the theory that bigger is always safer. The next section explains exactly why that theory costs you.

The Load Calculation Process

Before we recommend a number, we walk the home and build the calculation from the panel out. That starts at the main service panel, where we read the breaker schedule and identify every major circuit: HVAC, water heater, range, dryer, well pump, pool and spa equipment, and any subpanels feeding a shop or detached garage. We note the running and starting watts for each motor-driven load, because the surge values are what determine whether a unit can start your largest compressor without sagging the whole system.

From there we map which loads you actually want backed up. Many Fort Collins homeowners do not need every circuit on the generator. A whole-home transfer switch covers everything, but a managed system can prioritize heat, refrigeration, well water, and key outlets while shedding the pool heater or the second oven during the rare moments the rest of the house spikes. That decision directly changes which generator size makes sense, and it is the difference between a tight, efficient install and an oversized one.

We also factor in altitude and fuel. Fort Collins sits near 5,000 feet, and engines lose a measurable percentage of rated output at elevation, so a unit sized at sea level numbers can come up short here. We correct for that derate in the calculation rather than discovering it the first time a real outage hits. The output is a written recommendation that ties a specific kW rating to your specific loads, with the assumptions spelled out so you can see the reasoning rather than taking a salesperson’s word for it.

Don’t Oversize

It is tempting to over-buy capacity for peace of mind, but an oversized generator is a quiet, ongoing waste. The hardware costs more up front, and then it burns more fuel during every exercise cycle, the weekly five-minute self-test that keeps the unit healthy. Over years of operation those costs add up, and you got nothing extra for them because the capacity you paid for never gets used.

The bigger problem is mechanical. A correctly sized generator runs at 50 to 70 percent of rated load during your peak draw, which is exactly where the engine is most efficient and most durable. An oversized unit idles along at 25 to 30 percent load, and diesel and large gas engines do not like running light. That leads to wet-stacking, where unburned fuel collects in the exhaust, plus carbon buildup, glazed cylinder walls, and a shorter useful service life. You can actually wear out a too-big generator faster than a right-sized one.

The goal is to match the unit to the home so it spends its working life in that efficient band. That is why every recommendation we make starts with the load calculation, not a sales chart, and it is the same logic that keeps the system reliable when you finally need it at two in the morning during a blizzard.

What to Expect on Install Day

A standby generator install in Fort Collins is a contained, predictable project once permitting clears. We set the generator on a composite or concrete pad, typically along a side or back wall where clearances from windows, doors, and the gas meter meet code and keep the noise away from bedrooms. The transfer switch goes in beside or near your main panel, and we run the electrical and gas connections to tie it all together. On natural gas homes we coordinate the gas line sizing so the meter can actually deliver the fuel volume the unit demands under full load, which is a step that gets skipped surprisingly often.

Plan on two to four days from delivery to commissioning for a standard residential job, with the longer end driven by gas line work or a panel that needs attention before the transfer switch goes in. The permit and inspection lead time adds one to two weeks before install actually begins, so the calendar from signed proposal to a running system is usually three to five weeks. We handle the permit, the architectural review submission if your HOA requires one, and the inspection scheduling so you are not chasing paperwork.

Commissioning is where the work pays off. We program the automatic transfer switch, set the exercise schedule, configure any load management priorities, and then simulate an outage to confirm the generator starts, transfers, and carries your real loads within a few seconds. Before we leave, we walk you through the exercise routine, the basic maintenance intervals, and what the status indicators mean, so you know your system is ready before the first real storm tests it.

Common Questions

How long does a Fort Collins generator install take?

Plan on 2 to 4 days from delivery to commissioning for a standard residential job. Permit and inspection lead time adds 1 to 2 weeks before install starts, so the full timeline from signed proposal to a running system is usually 3 to 5 weeks.

What does a Fort Collins generator install cost?

The 22 kW Generac is the entry point, with the 26 kW and 32 kW stepping up from there. Kohler and Cummins equivalents typically carry a premium over the Generac.

Generac, Kohler, or Cummins?

Generac is the volume choice with parts available locally and a certified service network. Kohler runs quieter at 66 to 67 dB with premium aesthetics. Cummins is commercial-grade with a longer warranty and better load-shedding behavior.

Will my HOA approve?

Most Fort Collins HOAs allow standby generators with screening such as landscaping or a fence. If your neighborhood has an architectural review board, we submit the install plan and clearances for approval as part of the project.

Natural gas or propane?

Natural gas is the default if you have city service, which most Fort Collins homes do, since it feeds the generator continuously with no tank to refill. Propane is the alternative for homes without gas service and requires an above-ground tank sized to the run time you want.

Does altitude affect generator sizing in Fort Collins?

Yes. At roughly 5,000 feet, engines lose a measurable share of their rated output, so a unit sized to sea-level numbers can come up short here. We apply the elevation derate inside the load calculation rather than letting you discover it during a real outage.

Can a backup generator run my EV charger during an outage?

A Level 2 charger draws 7 to 11 kW, so on a 22 or 26 kW unit it means shedding most of the rest of the home while charging. A 32 kW generator can keep the house comfortable and still charge the vehicle, which is the main reason EV owners step up to the larger size.

Read more on our Fort Collins Backup Generators page, see our project gallery, or learn about the team.