A generator owner pulled a 20-year-old 13kW Generac and now wants to run it as a winter project on two 20-pound propane tanks with a Flame King 2-stage regulator and a 15-foot hose.
The goal is to determine whether this could be a shortcut to help when cold weather hits and backup power is needed.
Here's what to know
In a post on Reddit r/Generator, the owner said, "I removed a 20 year old 13Kw Generac with some issues today. Rather than scrap it I am planning to turn it into a winter project," but added that the fuel setup was the sticking point.
Although Flame King rates that 2-stage regulator at 345,200 BTU, commenters focused less on the regulator and more on the proposed fuel source: two 20-pound propane tanks feeding a generator the owner said uses around 250,000 BTU through a 15-foot half-inch hose.
One commenter warned, "20lb tanks will vaporize 50k-60k btu in warm temps. 100lb will vaporize 200k in warm temps." Another put it more bluntly: "At full load, the generator will simply be pulling more propane than those small tanks can deliver, regardless of the regulator rating."
For a generator this size, the key issue is not only how much propane is in the cylinders, but whether the tanks can turn liquid propane into vapor fast enough to meet demand.
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More background
Commenters generally drew a line between short bench testing and real use during an outage. One commenter wrote, "If you're just testing it will start up just fine. Running it under load ain't gonna happen for very long." Another added, "Those tanks will freeze up fast under load."
Because the owner described it as a winter project, temperature became a major part of the discussion. Propane tanks cool as fuel vaporizes, and in colder weather that effect can reduce pressure enough to leave the generator short on fuel even with propane remaining in the tank.
What can be done?
The practical advice in the thread centered on sizing for both stored fuel and vaporization capability. One said, "Minimum for me and most people is 2 x 100lb tanks and a primary and a secondary with some line," and another said, "I think 2x100lb tanks in a manifold setup is the minimum defensible for 13kw."
Larger tanks could help avoid wasted fuel, unreliable run times, and the hassle of swapping small grill cylinders during an outage. They also lower the odds that a generator will bog down as electrical loads increase.
If the goal is only to test an older unit before spending more money on it, several commenters indicated that small tanks may still serve a purpose.
Where can I learn more?
If you're weighing whether an old generator is worth rebuilding, it helps to look at how other homeowners are handling backup power. These stories cover generator-versus-battery decisions, propane's public image, and cold-weather backup choices.
• In Texas, a homeowner weighing overnight outage prep found a 190-pound generator too heavy to trust at 2 a.m.
• Energy experts say backup solar can deliver quiet resilience a fuel generator never will.
• Homeowners replacing aging generators are increasingly opting for next-gen models built around batteries and solar.
• Leaked recordings show propane executives attempting to deceive the public while defending the fuel's image.
• In Minnesota, a homeowner kept propane backup after seeing sub-zero heat pump data.
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