Summary:
When a nor’easter or the tail end of a tropical storm knocks the power out on the East End, a standby generator is what keeps the lights, the well pump, the refrigerator and the furnace blower running. Most of the ones installed around here run on propane. The generator gets the attention. The fuel behind it usually gets less.
This guide is about that fuel: how much a standby generator actually burns, how long a tank lasts once it starts, and how to have enough on hand before storm season rather than scrambling during it. It is written for homeowners who rely on propane service in Hampton Bays, where exposed shoreline and tree-lined streets make outages a real part of fall.
Why Propane Suits Standby Power
A standby generator sits idle for months and then has to start on command, often in the worst weather of the year. Propane is well suited to that job. It stores indefinitely in a sealed tank without breaking down, so there is no stale fuel to drain, no gummed-up carburetor and no stabilizer to remember, all problems that come with storing gasoline.
It is also already there. If your furnace, water heater or range runs on propane, the tank beside the house is the same supply a generator can draw from, with no cans to haul and no refueling in the rain.
One point to be clear about: choosing, sizing and installing the generator itself is work for a licensed electrician or a generator dealer. The gas line from the tank to the unit is run by a qualified installer, and our guide to gas line installation cost explains what that work typically involves. This article covers the propane side only: how much fuel you need, and how to have it in the tank when the power goes out.
How Much Propane a Generator Burns
Generator makers publish fuel use on the spec sheet, usually at half load and at full load. Those are the two figures to find for your model, because the real number depends on the unit’s size and how much of the house it is carrying at any moment.
As a rough guide, a smaller air-cooled home standby unit of around 10 to 14 kilowatts often burns somewhere near 1 to 1.5 gallons an hour at half load and about 1.5 to 2.5 gallons at full load. A larger whole-house unit in the 20 to 26 kilowatt range more commonly runs around 2 to 3 gallons an hour at half load and 3 to 4.5 gallons at full load. These are typical ranges, not figures for any particular model, and your spec sheet overrides them. If you are not sure which model you have, the model number is on a label on the enclosure, and the spec sheet is usually on the maker’s website.
Most homes spend an outage near half load or below. The refrigerator, well pump and furnace blower cycle on and off, and big draws such as central air or an electric dryer come and go. A house running air conditioning through a hot August outage will sit closer to full load.
Now stretch that across a real outage. A 22 kilowatt unit averaging 2 to 2.5 gallons an hour burns roughly 50 to 60 gallons a day. After a bad storm on the East End, hard-hit streets can be without power for several days, so three days is 150 to 180 gallons for the generator alone, and five days is 250 to 300. Our guide to how long a propane tank lasts puts those numbers next to everyday winter heating use.
Why a Heating Tank May Fall Short
Plenty of homes add a standby generator to a propane system that was sized years ago for heat and hot water. That tank may be too small for the combined load.
Start with usable gallons. A tank is filled to about 80 percent of its water capacity, so a 500 gallon tank holds roughly 400 gallons when full, a 250 holds about 200 and a 120 about 96. The LP tank sizes and capacity chart lists every common size. You also want a reserve left at the end, so the gallons you can actually spend in an outage are fewer again.
Then stack the loads. In January a year-round home might burn 3 to 8 gallons a day on heat alone. Add a large generator at 50 to 60 gallons a day and a full 250 gallon tank could be empty in about three days. A 500 gallon tank that starts half full holds around 250 gallons, which a whole-house unit and a furnace can work through in four days or so.
That is why generator manufacturers usually list a minimum tank size for each model, and why whole-house units are commonly paired with a 500 gallon tank or larger. Tank size also affects vaporization, the rate at which liquid propane turns into gas. A small tank in cold weather may not vaporize fast enough to feed a large generator and a furnace at once. Your generator installer should confirm what the unit needs, and if the answer is a bigger tank, our propane tank installation team can talk through the options.
The 80 and 30 Percent Rules in an Outage
Two numbers govern every propane tank. The first is 80 percent. Tanks are filled to about 80 percent, not 100, because liquid propane expands as it warms and needs room at the top. A gauge reading near 80 after a fill means the tank was filled correctly, not short. The gauge reads a percentage of the tank’s capacity, not gallons, so multiply by the tank size to see what you actually have.
The second is 30 percent, the usual point to arrange your next propane delivery. In normal weather that leaves time to schedule a fill with a cushion to spare. With a generator on the tank, 30 percent deserves a second look. On a 500 gallon tank it is about 150 gallons, which a large standby unit can burn in two and a half to three days on its own.
So many generator owners work to a higher line during storm season, treating something like 50 or 60 percent as the point to call from late summer through fall. The idea is simple: the tank should never go into a storm near its reorder line, because the outage itself may be what uses up the reserve.
Fill Before the Storm, Not During
The time to top up is when the forecast first shows a storm heading your way, or better, before the season starts. Once a storm arrives, several things work against a delivery.
Roads come first. High winds, downed trees and fallen lines close streets, sometimes for days, and a loaded propane truck cannot safely work under live wires or through flooded roads. Deliveries wait until conditions are safe, and utility crews often have to clear a street before anyone else can use it. On the East End, where a handful of main routes carry most of the traffic, one blocked road can hold up deliveries to a whole neighborhood.
Demand comes next. When a whole area loses power at once, every home with a generator starts burning fuel at the same time, and many call in the same few days. After a major storm, deliveries are scheduled as roads open and in the order conditions allow, so no one should plan on a fill arriving at a set time.
Then there is the tank itself. A fill needs clear, safe access to the tank and its fill valve. Standing water, drifted snow or a tree across the driveway can hold a delivery up even after the roads reopen, so keep the path to the tank clear and make sure a driver can find it.
A full tank going into the storm sidesteps all of that. Check the gauge in late summer, again before any named storm or strong nor’easter, and call early if it is below your storm-season line. After an outage, look the tank over, and if you smell gas, leave the house and call from a safe distance.
What Hampton Bays Homes Should Plan For
Hampton Bays sits at the gateway to the South Fork, just west of the Shinnecock Canal, with Shinnecock Bay to the south and Great Peconic Bay to the north. Much of the hamlet is close to open water, and it takes the full force of nor’easters in fall and winter and the remnants of tropical storms from late summer into October. Homes in low spots near the bays should also think about flooding: an above-ground tank there needs to be properly anchored, which is a question for whoever installed it.
The streets add to it. Many roads in Hampton Bays are lined with mature oaks and pines, and most homes are fed by overhead lines. A strong wind brings limbs down onto those lines, which is why outages can outlast the storm by a day or more on hard-hit streets.
The housing mix matters too. Year-round homes need their tank ready for heat and generator together from October on, since the furnace and water heater draw from the same supply. Our overview of propane home heating services covers that side of the system. Summer and weekend homes face a different risk: a house closed up after Labor Day may sit through the peak of hurricane season with no one checking the gauge. Most standby units also run a short automatic exercise cycle, often weekly, which burns a little propane even when the house is empty.
If a generator is protecting a second home from frozen pipes or a flooded basement while you are away, the tank needs enough in it to do that job with no one on site. Before you close up for the season, have the tank topped up and note the reading.
Getting Your Tank Ready for Storm Season
A standby generator turns a multi-day outage into an inconvenience, but only if the propane is there to run it. Find your generator’s fuel use on its spec sheet, multiply it out over a few days, and compare that with the usable gallons in your tank above your storm-season reorder line. If the numbers leave no room for heat as well, talk to your generator installer about tank size before winter. If you are adding a generator this year, bring your propane supplier into the conversation early, so tank size and fuel supply are settled before the unit is set.
Then keep it simple. Go into every storm with a full or nearly full tank, check the gauge before you close up a seasonal home, and call early rather than in the middle of the storm.
Liberty Gas delivers propane to homes in Hampton Bays and across Suffolk County from 225 Old Riverhead Rd in Westhampton Beach. To top up before storm season or ask about your tank, call 631-288-0902, or request a propane delivery online.
