When a storm rolls through Sugar Land, the first question is always the same. When will the power come back? By day three, that question changes. How long can my generator keep going? Gulf Coast storm season does not hand out short outages. Power can stay out for days here. Sometimes longer.
Below, you'll find how long a whole-home generator can run on natural gas or propane during an extended outage. You'll also learn what really sets the limit. If you run on propane, your answer depends on something most homeowners overlook. It sits right outside your window, and it runs all summer.
We'll start with propane and the tank in your yard. Then we'll cover natural gas, what actually shuts a generator down, and how to size the setup. You'll finish with a plan for storm season.
It depends on three things:
The math is simple. Take your tank size. Divide it by your burn rate. That gives you your hours.
Your manufacturer publishes a fuel consumption chart. It lists gallons per hour at half load and full load. That chart gives you your real number, not a guess.
Natural gas works differently. There is no tank to empty. It runs as long as the utility keeps the gas flowing.
For both fuels, oil is the true limit. Not the fuel supply.
Search this question online and you'll get wildly different answers. One page says a tank lasts four days. Another says ten. Both can be right.
The tank did not change. The load did.
In a Sugar Land home, central air conditioning is the largest draw by far. It pulls hard, and it pulls constantly. In August, it barely rests. That single appliance can decide your entire runtime.
Here is what pulls the most power in most homes:
Your manufacturer's chart shows this plainly. It lists a burn rate at half load and another at full load. Those two numbers are often far apart. The gap between them is where your extra days live.
So size your tank for the outage you fear, not the one you hope for. A February outage and an August outage burn very differently. Plan for August.
You can also stretch a tank by running one AC zone instead of the whole house. Cutting AC entirely is not realistic in Gulf Coast heat. Reducing it is.
When we size a propane tank, we walk homeowners through their own load first. We look at AC tonnage, the panel, and which circuits actually need to stay live. The tank size follows that number. It should never be a guess.
You might think a refill solves all of this. During a storm, it usually does not.
Once a storm enters the Gulf forecast, propane suppliers get buried. Every tank owner calls at once. The schedule fills within hours.
Then the roads go. Delivery trucks cannot reach a flooded street, and they will not try. Fort Bend County holds water after a heavy rain. Your driveway may be fine while the road two blocks over is not.
So plan around one hard rule. The fuel in your tank when the storm hits is the fuel you have.
Top off before storm season starts, not during it. Fill the tank in May or early June. Keep it well above a working reserve straight through the fall.
Natural gas works differently. There is no tank to run dry.
A natural gas standby generator ties straight into your home's gas line. Nothing to refill. No supplier to call. No delivery truck to wait on.
That is why the answer sounds almost too good. Your generator keeps running as long as the utility keeps the gas flowing.
Here is the part that matters during a storm. Gas lines run underground. Power lines run overhead. Wind takes down poles and wires. It rarely touches buried pipe. So gas service often holds while the grid stays dark.
But "runs as long as the gas flows" has real limits. A few things can cut it short:
One detail gets missed on natural gas installs. The gas line has to be sized for the unit. Our electricians check that line during every install, because an undersized line starves the generator under load. A unit that runs fine on a mild day can stumble when the AC kicks on.
Fuel gets all the attention. It is rarely what ends the run. Here is what actually shuts a standby generator down during a long outage.
1. Oil — This is the real ceiling. Your engine runs nonstop for days, and the oil breaks down. Every manufacturer sets an interval for checking and changing it during continuous use. Follow that interval and keep going. Miss it and you risk engine damage that outlasts the storm.
2. Overheating — Standby units shed heat through air or liquid cooling. A Gulf Coast August pushes that system hard. Let debris block the airflow, or run with a failing cooling system, and the unit shuts itself down to protect the engine.
3. Overload — Ask for more power than the unit can make, and it trips. Turn on the AC, the dryer, and the range together, and you can find that limit fast.
4. Air filters and debris — Storms push leaves, dirt, and water into everything. A choked air filter starves the engine. This one is easy to check and easy to forget.
5. Deferred maintenance — A generator that has not been serviced in two years will not finish a two-week outage. That failure did not start during the storm. It started long before it.
Notice what these five have in common. None of them are fuel. Your tank size sets your ceiling. These decide whether you ever reach it.
Most runtime problems trace back to the install.
An undersized generator strains under a normal Sugar Land load. It runs hot. It burns fuel hard. Then it shuts down on the day you need it most. An oversized unit has the opposite problem. It burns fuel it never needed to burn, which costs you days on propane.
The fix is a load calculation. We measure what your home actually pulls. Not what a sizing chart guesses. That number drives the generator size, and on propane, it drives your tank size too.
A transfer switch does the managing for you. It watches for the outage and starts the unit automatically. It prioritizes your essential circuits, so a startup surge from the AC compressor does not overwhelm the system. You should not be flipping breakers by hand at 2 a.m.
Your panel matters as much as the generator. Older panels sometimes need work before a standby unit can be tied in safely. We check the panel first, because a generator is only as sound as what it feeds.
One safety rule has no exceptions. A generator must connect to your home through a transfer switch. Never any other way. The Electrical Safety Foundation International warns that wiring around a transfer switch sends power backward into utility lines, which can injure the crews working to restore your neighborhood.
The work that carries a generator through a two-week outage happens before the storm, not during it.
That last item solves most of the others. Sizing, fuel burn, and runtime all trace back to load.
Your runtime depends on tank size, generator size, and how much power your home pulls. Divide your tank size by your burn rate to get your hours. Your manufacturer's fuel consumption chart lists that burn rate at half load and full load. Those two numbers are often far apart.
A natural gas generator runs as long as the utility keeps the gas flowing. There is no tank to empty. Gas lines sit underground, so service often holds during storms that take down power lines. The practical limit is your oil change interval, not the fuel.
Yes. Central air conditioning is the largest power draw in most Sugar Land homes. It makes the generator work harder and burn fuel faster. On propane, running the full AC system can cut your total days sharply compared to running essentials only.
Oil is usually what stops it first. Engines running nonstop for days need an oil check and change at the interval your manufacturer specifies. Overheating, overload, clogged air filters, and skipped maintenance also shut units down mid-outage.
Plan as if you cannot. Suppliers get overwhelmed once a storm enters the Gulf forecast. Delivery trucks will not reach a flooded street. Top off your tank before storm season and keep it full through the fall.
Abacus Plumbing, Air Conditioning & Electrical in Sugar Land, TX • 104 Industrial Blvd, Sugar Land, TX 77478 • 281-215-3046
Open Including Holidays
ALAN O’NEILL M-20628 | TACLA135747C | TECL 30557
© 2025 Abacus Plumbing, Air Conditioning & Electrical. All Rights Reserved