The Jetboil Joule cooking system is a liquid-feed canister, high-volume cooking system.
Liquid feed canister systems take advantage of the canister in an inverted configuration to deliver liquid fuel to the burner, in contrast to upright canister systems, which deliver fuel as vaporized gas to the burner.
The Jetboil Joule is an inverted canister, liquid-feed, integrated stove system that includes a 2.5L pot with an integrated heat exchanger.
The primary advantage of a liquid feed canister system is that it offers better cold weather performance, since the vapor pressure in the canister isn’t changing while the stove is operating.
In the Jetboil Joule system, the canister is inverted, with the liquid feed tube exiting from the bottom of the stove and controlled by the wire valve. The entire canister-fuel delivery/control unit is contained in a cage that provides stability, as well as simplicity of form and function. Most inverted canister stove systems require the canister to be remotely detached from the stove unit.
In upright canister systems, as the vapor pressure in the canister decreases, the canister temperature decreases, and the rate of fuel delivery to the burner decreases.
Thus, upright canister systems don’t work so well in the cold, or for boiling large volumes of water at cooler ambient temperatures.
The Jetboil Joule attempts to solve this problem not only by inverting the canister, but also by preheating the liquid fuel before it hits the burner, which allows it to maintain power in cold temperatures.
The tube that feeds liquid fuel to the burner is preheated by the burner, thus vaporizing the fuel as it leaves the burner head for efficient combustion. This design is commonly used in other liquid fuel (e.g., white gas) stoves.
In addition to the inverted canister configuration and the preheated liquid fuel delivery tube, the Jetboil Joule pot has an integrated heat exchanger, which allows for more efficient heating of the pot, and greater fuel efficiency.
The Joule offers a 2.5L pot with an integrated heat exchanger. Our testing has shown time and again that integrated heat exchangers that have large surface areas with the heat exchanger fins in direct contact with the cooking pot bottom offer significant fuel efficiency gains.
The other unique feature of the Jetboil Joule is that it’s an integrated system that consists only of two parts - the stove base and the pot - which connect to each other to make one solid unit during operation.
There are no separate parts such as windscreens, fuel pumps, or external heat exchangers, and the entire stove unit - with an attached fuel canister, nests neatly into the pot for space efficient storage.
Features & Specifications
The approximate pot volume of the Jetboil Joule is 2.5 L - just about the right size for melting snow for a 2 or 3 person cook group, or for three season cooking with groups of 3 to 5 people.
Not including the weight of fuel canisters, we verified the weight of the entire system (stove base + pot) as 27.6 oz.
Table 1. System Specifications (Comparison of Jetboil Joule & MSR Reactor 2.5L System)
|Stove Weight||Pot Weight||Total System Weight||Nominal Water Capacity ||Inside Pot Dimensions|
|MSR Reactor 2.5L||6.3 oz||14.9 oz||21.2 oz||72 oz (2.1 L)||6.875 in (dia) x 4.375 in (height)|
|Jetboil Joule||11.7 oz||15.9 oz||27.6 oz||88 oz (2.6 L)||6.125 in (dia) x 6.0 in (height)|
 Nominal water capacity was calculated as the amount of water that the pot can hold up to a point 0.75 in below the top rim of the pot.
Other features of note include a lid that serves as a pasta strainer, a silicone-coated folding handle that contains the system when packed away, a piezo-electric igniter, a neoprene pot cozy that helps the system retain heat during cooking, and enough fine fuel line control to be able to simmer foods at low heat.
Using the Stove
Using the Jetboil Joule simply involves removing the stove base, attaching a fuel canister, filling the pot with water, attaching the pot to the stove base, opening the fuel line valve, and clicking the piezo-electric igniter to light the stove.
Setup is even easier the second time around, because the fuel canister can remain attached to the stove base until it empties and needs to be changed out with a new canister.
Baseline Fuel Efficiency
Let’s compare the Jetboil Joule with another integrated canister stove system, the MSR Reactor with its 2.5 L pot (note that the Reactor system is an upright, or gas-feed system, as opposed to the Joule, which is an inverted, or liquid-feed system).
For the purpose of this baseline test, both system pots were filled with 72 oz (2.1 L) of 55 deg F tap water. The test was performed indoors at an ambient temperature of 65 deg F. Boil times represent the time to a rolling boil. The tests were performed at an altitude of 4,750 feet above sea level. All other test procedures were based on the test description in the Lightweight Stove Systems for Group Cooking series. See Table 2 for the results.
Table 2. Baseline Comparison of the Jetboil Joule and MSR Reactor: Boil Time & Fuel Efficiency
|Water Volume Boiled (L)||Boil Time (mm:ss)||Fuel Consumed (g)||Canister Capacity (# Pots Boiled Per 8 oz net Canister)||Fuel Efficiency (g of fuel consumed per L boiled)|
|MSR Reactor||72 oz (2.1 L)||12:30||20 g||11.4 pots (23.9 L)||9.5 g / L|
|Jetboil Joule||72 oz (2.1 L)||5:45||20 g||11.4 pots (23.9 L)||9.5 g / L|
- The Jetboil Joule is a much louder stove than the MSR Reactor. At a distance of 12 inches from the burner head, noise was measured at 78 dB for the Joule and 53 dB for the Reactor (ambient sound in the space where the testing was performed was measured as 49 dB).
- Both stove systems required the same amount of fuel to boil the same amount of water. This indicates that they have comparable efficiencies (i.e., when efficiency is defined as the amount of fuel consumed for a given amount of water boiled).
- The Jetboil Joule is a powerhouse of a stove. Its boil time was less than half that of the MSR Reactor system.
- In the mild and warm test environment of an indoor kitchen, it’s clear that the Jetboil Joule offers a huge operating efficiency advantage (as defined by decreased boil times relative to the MSR Reactor system). In theory, because the Reactor is an upright (gas feed) canister system, and the Joule is an inverted (liquid feed) canister system, these differences should be even more pronounced at cold temperatures and other scenarios where boil times may be extended (e.g., melting snow). Future testing will explore the Joule’s cold weather performance.
I have to admit that I was pleasantly shocked by the Joule’s operating efficiency. A blisteringly fast boil time for a large volume of water, a system that was easy to setup and operate, and nesting storage that allowed the fuel canister to remain attached are its strong points.
The canister can remain attached to the stove unit and stowed inside the pot for simple storage and easy setup the next time it’s used.
We’ll reserve our review rating pending long term testing of cold weather performance, a more detailed evaluation of the stove’s design, engineering, and construction, and consideration of its carbon monoxide production.
But for now, there’s a lot to like about the simplicity and fast boil times from the Jetboil Joule, especially for group cooking that requires larger water volumes.