Mr. Heater refill kit and Fuel Keg review: Is it worth the switch?

Last Updated on 2026-01-29 by NatureCrank

Propane is a cornerstone of off-grid living. Whether you are boondocking in an RV or prepping a remote cabin, its versatility for cooking, heating, and power generation is unmatched. However, the standard “green” 1lb disposable cylinders have long been the weak link in an otherwise efficient system.

In this review, I’ll dive into why the Mr. Heater Fuel Keg refillable 1lb propane bottle is a game-changer for cost, safety, and environmental impact.

Why you should stop using disposable 1lb propane tanks

If you’ve spent any time in the “real world” of off-grid life, you know those green disposable tanks are a nuisance.

• Safety risks: Refilling a disposable tank is not only dangerous—it is technically illegal for transport under U.S. DOT regulations. Disposables have thin walls and lack the overpressure relief valves found on true refillable tanks.
• Environmental impact: According to Flame King, roughly 40 million disposables are used annually. Most end up in landfills or, worse, littered in the woods.
• Cost inefficiency: At current retail prices (approx. $18.87 for a four-pack at Walmart), you are paying about $4.72 per gallon. By refilling from a standard 20lb tank at $2.99/gallon, you save nearly 40% per refill.

And just the feel alone. The empty weight of a Fuel Keg is 1.52 lbs (that’s why it has a 12-year DOT certification), and an empty green cannister weights about .8 lbs.

Mr. Heater vs. Flame King: Refillable tank comparison

When choosing a refillable system, you generally have to pick a “side” because the kits are proprietary. Here is how the Mr. Heater Fuel Keg stacks up against its main competitor.

The Mr. Heater Fuel Keg refill kit in action

The Mr. Heater Fuel Keg and Refill Kit is designed specifically to bridge the gap between a 20lb bulk tank and your small portable appliances like the Mr. Heater Little Buddy.

Key features and performance

The standout feature is the integrated bleeder valve. Unlike other systems that require a hex key to release air pressure, the Fuel Keg allows you to release pressure by hand. This ensures you get a “true full” 16-ounce fill every single time, even in cold weather.

The refill adapter features an internal pressure relief valve and a proprietary connector that ensures the pin only opens when safely seated. This means propane won’t spray or leak unless the connection is 100% secure, a massive safety upgrade over generic brass adapters.

Pros

• Speed: I’ve found that I can consistently refill a tank in about one minute.
• Build quality: These tanks are noticeably heavier than disposables, which gives me peace of mind regarding long-term durability. Mine have survived a full winter without rust.
• Tool-free design: The kit includes stabilizing feet for your 20lb tank and a tap valve that requires no extra tools.

Cons

• Proprietary system: You cannot use the Mr. Heater adapter to fill Flame King tanks, or vice versa.
• Weight: They are a bit heavier, which might be a concern for ultralight backpackers, though it’s a non-issue for RVers or car campers.

How to refill a 1lb propane tank safely with the Fuel Keg kit

1. Chill the Fuel Keg: For the best results, put your empty 1lb tank in the freezer for 15–20 minutes.
2. Invert the 20lb tank: Connect the refill adapter to your 20lb source tank and flip the source tank upside down using the provided stabilizing feet.
3. Connect and open: Screw the Fuel Keg onto the adapter and slowly open the 20lb tank valve.
4. Vent the air: Open the bleeder valve on the Fuel Keg until liquid propane starts to sputter, then close it immediately.
5. Disconnect: Turn off the source tank and unscrew your freshly filled 1lb bottle.

Pro-tip for the “winter warriors”

If you are refilling in freezing temperatures, the pressure in your 20lb tank will be lower. To get a full 16oz fill, it is even more critical to use the freezer trick for the 1lb bottle. The temperature differential between the warm(er) 20lb tank and the frozen 1lb bottle creates a vacuum effect (differential) that pulls the liquid in much faster.

Frequently asked questions about refillable propane bottles (FAQ)

Final verdict: Is the Mr. Heater Fuel Keg worth it?

If you are a frequent propane user, the kit pays for itself within the first 10–15 refills. For those living off-grid or in an RV, the Mr. Heater Fuel Keg is the superior choice over Flame King due to the tool-free bleeder valve and the speed of the fill. It’s a sustainable, cost-effective, and safer way to stay warm and well-fed.

These also make great kits for the homeless. While The Maximus Fund is just a dream at this point, these kits will eventually be distributed to the homeless