Whole House Generator Installation in Nashua, NH

What Whole House Coverage Honestly Means

Whole house does not mean every load in the home running at the same instant with no limits. No sensibly sized residential generator does that, and any quote implying otherwise deserves a hard look. Whole house means the entire home stays usable during an outage: every room has light, every system you depend on works, and the heavy loads are managed so they take turns instead of stacking up. In practice, a whole house install pairs a generator in the 18 to 26 kW range with a service rated automatic transfer switch and load management. The switch carries the full electrical service of the home. The load management watches for the moments when too many big loads want power at once, an air conditioner starting while the dryer and the electric range are both on, and briefly pauses one load so the others start cleanly. You rarely notice it happening. What you notice is that the house works.

The alternative reading of whole house, a generator big enough to start and run literally everything simultaneously, pushes into oversized equipment, higher fuel burn, and a price that buys capacity you will use for a few seconds a year. Good installers size for real life, with headroom, not for the theoretical worst second. That is the approach on this page: honest coverage, properly engineered.

The Loads That Decide Your Size

Square footage is a rough first filter, but loads decide the generator. Walk a typical Nashua home and count what actually draws power. Heating comes first in New Hampshire. A gas or oil furnace with an electric blower is a modest load. A heat pump with electric backup strips is a large one, and an all electric home is the hardest case in sizing. Cooling is next: one central air conditioner is a common planning load, two systems or a large five ton unit change the answer. Water follows: a well pump is a motor load with a real starting surge, and a sump pump is smaller but non negotiable in a wet basement. Then the kitchen: an electric range and oven draw heavily, a gas range barely registers. Laundry splits the same way: a gas dryer is light, an electric dryer is one of the biggest loads in the house. Add a hot tub, a pool pump, a workshop, an electric vehicle charger, or a finished basement with its own systems, and the total moves again.

Motors deserve their own paragraph because they are where undersized installs fail. Anything with a motor, air conditioner compressors, well pumps, sump pumps, furnace blowers, refrigerator compressors, draws a surge of extra power for a few seconds at startup, well above its running draw. A generator that looks adequate on running watts can sag or stall when two motors start together. Manufacturer sizing guidance works from nameplate starting and running requirements for exactly this reason, and installers add headroom above peak load, in the range of 20 to 25 percent in commercial guidance, so the generator is not living at its limit. Load management exists to sequence those starts. When you read the sizing guide, the worked examples show the surge math in plain numbers.

The kW Ladder for Whole House Coverage

Read the table as a starting point, not a promise. Two 2,800 square foot Nashua homes can land two bands apart if one has gas heat, a gas range, and one air conditioner, and the other has electric heat strips, an electric range, two air conditioners, and a hot tub. The load calculation on your own panel is the final word, and a good quote shows its work.

How the Transfer Switch and Load Management Work

The automatic transfer switch is the brain of the system. It sits between the utility feed and your home. Under normal power it passes utility electricity through and keeps watch. When the utility voltage drops out, the switch waits a few seconds to be sure it is a real outage and not a flicker, signals the generator to start, lets it come up to speed and voltage, then transfers the house onto generator power. Total time from outage to backup power is usually measured in seconds. While the generator runs the home, the switch keeps watching the utility side. When utility power returns and stays stable for a set period, the switch transfers the house back, and the generator runs a short cool down before shutting off. At no point can generator power flow back into the utility lines, which is a safety requirement, not a feature.

Load management modules work alongside the switch. Each module watches one heavy load: an air conditioner, an electric dryer, a range, a hot tub. When the generator is near its comfortable limit, the modules shed a load briefly, then restore it when capacity frees up. This is what lets a 22 or 24 kW generator carry a home that would otherwise need a much larger unit. It is also why two quotes with the same generator size can perform very differently: one engineered the loads, the other just connected the wires.

Fuel for a Whole House System

Whole house coverage burns more fuel than essentials coverage because the generator is carrying more of the home, and fuel planning deserves the same care as sizing. On natural gas, supply is effectively unlimited during most outages, but the gas meter and line must be sized for the generator at full load on top of the home's other gas appliances, something the installer verifies and upgrades when needed. On propane, runtime is arithmetic. A 22 kW unit burns roughly 2.45 gallons per hour at half load and about 3.71 gallons per hour at full load by manufacturer specification figures. A 500 gallon tank, filled to its usual 80 percent, holds about 400 usable gallons, which works out to several days of continuous running at typical mixed loads. The fuel page does this math in full and covers tank sizing honestly, including the fact that your real load cycles up and down all day, so real world runtime usually beats the full load figure.

What Whole House Installation Costs Here

The most useful local planning figure is the range a southern New Hampshire installer publishes for this area: $10,000 to $24,500 installed for a whole home standby generator, depending on size, gas line work, and transfer switch complexity. Whole house jobs cluster in the middle and upper parts of that range because the generator is bigger and the switch and load management work is more involved. Generac's national cost guidance of $8,000 to $16,000 including the generator shows what the same work averages in lower cost markets, and Angi's 2026 national data runs lower still because it blends in small essentials installs. For a Nashua whole house quote, judge it against the local range and against the completeness of the scope: generator, switch, load management, pad, fuel work, permits, startup, and walkthrough, all named in writing.

The factors that move a whole house quote most are the panel. An older or full panel, or a service that needs upgrading, adds real work. Placement matters too: a generator set close to the panel and the gas source is the cheap version of the job, while a long trench across a finished yard is not. Propane adds tank cost when a tank is part of the project. None of these should appear as surprises after signing. The cost guide lists every common driver with the published figures behind it.

The Installation, Step by Step

Whole house installation follows the same sequence as any standby install, with extra attention to the load work. It starts with a site visit and load calculation, a check of the panel and service size, the fuel source, and the placement. Permits follow: Nashua's Building Safety Department handles applications, a building permit covers only the structural portion of a project, and separate permits cover the electrical and gas sides of the job, each with its filing fee. On install day or days, the pad is set and the generator placed, the fuel line is run, the transfer switch goes in and the panel work is done, load management modules are wired to the heavy loads, and the system is started, transferred back and forth under load, and tested. Most physical installs run one to two days. The finish is a walkthrough: controller, exercise schedule, status lights, monitoring setup where fitted, manuals, and the maintenance plan. The process page gives the full timeline with the permit and inspection steps in order.

Living With a Whole House Generator

Ownership is mostly invisible, which is the point. The generator exercises itself briefly on a schedule, usually weekly. The controller shows a ready status when all is well, and monitoring, where fitted, can send alerts for faults or missed exercises to a phone. Your jobs are small: keep the area around the unit clear of snow and brush, do not store anything against it, and keep up the annual service. That service, oil, filter, spark plugs, battery test, load test, and a full operational check, is what keeps the warranty in good standing and the start reliable. During a long outage there is one habit to learn: after every 24 hours of continuous running, air cooled generators should be shut down for about 30 minutes so oil and the usual continuous use checks can be done. The maintenance page explains the full routine.

Noise is the other everyday question. A whole house generator under load sounds like a working engine in a sound dampened enclosure, noticeable near the unit, modest across the yard, and far less than a portable generator screaming on a driveway. Placement on the far side of the house from bedrooms, and an exercise time set for midday rather than early morning, keeps the peace with your household and your neighbors.

Whole House Coverage in a Long Outage: How It Plays Out

Hour one is the part everyone imagines: the transfer, the lights back, the furnace cycling, dinner cooked on schedule. The deeper value shows up later. On day two, the laundry runs because life does not pause for the utility. The home office is simply at work. The sump pump cycles through a thaw without anyone standing watch in the basement. Showers are hot because the water heater never fell behind. On a propane system, day two is also when the tank gauge becomes part of the household routine, the same check the fuel page builds its math around, and when the brief 24 hour shutdown for the oil check gets done during a calm stretch rather than skipped. Families who have ridden out a multi day New Hampshire outage on whole house coverage describe the same thing: the outage becomes weather news instead of a household emergency. That ordinariness is the entire product. It is also why the sizing and load management work on this page matters, because ordinariness on day three is engineered on install day, in the surge math and the shed priorities, long before the storm.

Panel and Service Considerations for Whole House Work

Whole house coverage makes a promise through your electrical service, so the service itself gets examined. Many Nashua area homes run 200 amp service, which pairs naturally with a service rated transfer switch. Older homes may carry smaller services, panels that are full, or equipment old enough that replacement is the honest recommendation. None of that blocks a whole house install. It scopes it. The quote should describe the panel work as its own line, with the reason attached: room for the transfer equipment, condition of the existing gear, or capacity for the managed loads. Load management also earns a second mention here, because it is frequently the tool that lets an existing service carry whole house coverage without a service upgrade, by guaranteeing that the managed heavy loads never demand more than the system can give. When two quotes for the same home differ on panel work, ask each installer to explain the other's position. The one who can is usually the one who looked carefully.

Request a Generator Quote

Common Questions