Homeowner questions 60-pound tank requirement after smaller tanks powered an eight-day outage

"A larger engine requires a greater rate of fuel delivery, so larger generators require larger tanks."

While looking for a new generator, one homeowner was startled by a product listing that said the unit needed a propane tank of at least 60 pounds.

What to know

On Reddit, the homeowner said they had gotten through an eight-day outage without trouble using a propane-powered generator connected to 20- and 30-pound tanks. Confused by the new requirement, they asked other generator users why a larger tank would be necessary when smaller ones had worked before.

In addition to storing enough fuel, a propane tank has to deliver vapor quickly enough to keep the generator running.

One commenter put it this way: "A larger engine requires a greater rate of fuel delivery, so larger generators require larger tanks."

More background

Other commenters said frozen 20-pound barbecue tanks can be a problem for generators in the 12- to 15-kilowatt range. They said the issue comes down to fuel demand versus vapor supply: bigger generators can use propane faster than a small tank can turn it into vapor.

In that situation, the tank’s ability to supply fuel becomes the bottleneck, even if propane is still inside.

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The post did not say which model had been used during the outage or which one required the 60-pound minimum. Without those details, it is impossible to know whether the two generators had similar fuel needs.

Generator product descriptions can spell out propane-tank requirements clearly. A standard 20-pound barbecue cylinder may look convenient, but it may not work as a substitute for the larger tank a particular generator needs.

Where can I learn more?

Other homeowners have also run into confusion when matching a generator to its fuel supply.

• A generator owner weighing two 20-pound propane tanks for a 13kW unit was warned about freezing.
• At 14 degrees Fahrenheit, owners said 20-pound tanks can freeze before they are half empty.
• A cabin’s 22-kW backup plan was derailed by a missing propane tank.
• One homeowner received a recommendation for a 9,600W generator, but commenters cautioned about heavy fuel use.
• A homeowner considering a 7,000-watt tri-fuel generator learned that natural gas lowers output to 5,500 watts.