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Reviews > Cook and Food Storage Gear > Stoves > Primus ETA Power Stove > Test Report by Richard Lyon
Primus EtaPower EF Stove
TEST SERIES BY RICHARD LYON
Initial Report June 25, 2007
Personal Information and Backpacking Background:
I've been backpacking for 45 years on and off, and regularly in the Rockies since 1986. I do a weeklong trip every summer, and often take three-day trips. I'm usually camping in alpine terrain, at altitudes 5000 to 13000 ft (1500 - 4000 m). I prefer base camp backpacking, a long hike in with day trips from camp, but I do my share of forced marches too. Though always looking for ways to reduce weight, I'm not yet a lightweight hiker, and I usually choose a bit of extra weight over foregoing camp conveniences I've come to expect.
June 25, 2007
PRODUCT DESCRIPTION AND DETAILS
With the EtaPower EF the venerable Swedish firm of Primus, whose stoves accompanied Amudsen and Shackleton to Antarctica in the first two decades of the twentieth century, joins the era of heat exchanger canister stoves. The Eta is more than a stove. It is truly a cooking system. This system includes (a) a burner unit attached to a base plate, with piezo igniter, flexible metal hose, and attached "appliance" of Lindal valve and knob for adjusting the flame; (b) wind screen; (c) a 2.1 liter (2.2 qt) cook pot (Primus calls it the EtaPower pot or Eta-pot) with attached heat exchanger ring; (d) a frying pan that doubles as a lid for the pot; (e) a detachable pot gripper; and (f) a repair multitool. All these are stored in a zippered pouch made of insulated heavy-duty fabric (nylon?). The top piece of the pouch has an inside zippered pocket, a very convenient place to store the printed instruction booklet and multitool. Primus also includes a round cloth piece to be placed between the cooking unit and the pot when these are nested for storage, to avoid friction.
Primus has this to say about the Eta: "The stove’s high efficiency rate allows for fast boiling times, less fuel consumption, a lower total weight, and all in all a more environmentally friendly stove."
Manufacturer: Primus AB
* Primus does not indicate whether its listed dimensions are of the cooking system
only or cooking system, pouch, and cloth.
Output, listed: 2000 W / 7150 BTU/hr
Recommended temperature: (From the website) "Autumn/spring, generally down to +/- 0°C [32 F], temporarily -15°C [5 F]."
Appearance. The EtaPower EF pot, frying pan, and windscreen are made of aluminum, matte grey on the outside and black on the inside. The inside of the pot and frying pan are treated with a coat of non-stick titanium. The pan has the Primus logo on one side and volume markings, in increments of 0.2 liter (slightly less than one cup) increments on the opposite side, inside the pot but visible (in mirror image) on the outside as well. The storage pouch is black with the Primus name and logo on the lid. The cloth piece is also black and has "PRIMUS" in large letters across the underside. All pieces nest easily inside the pot, with room to spare. One aspect of my testing will be to see what I'll store in the extra space. A 225 g (7.9 oz) Primus canister, the one I had on hand, doesn't quite fit inside the pot with the cover on.
My first reaction shouldn't have been unexpected, as the dimensions are clearly stated on the manufacturer's website, and Primus advertises a capacity of one to four campers. Nevertheless the size of the Eta startled me – man, this baby is large! Another testing criterion, probably the most important one, will be under what circumstances this stove's utility and performance will justify its bulk and weight.
Instructional materials. Incomprehensible technical booklets with indecipherable technical pictures are a pet peeve. I'm happy to report that I found neither phenomenon in the printed booklet accompanying the Eta. Primus sets out the standard safety warnings for use of any stove, any canister stove, and any use of the propane/butane fuel used in canister stoves, but also includes descriptions of assembly, usage, maintenance, and troubleshooting for the Eta in plain, easy-to-read English with simple but helpful illustrations. The booklet includes these materials in ten languages in addition to English.
Primus also includes a DVD, in English and Swedish, that includes basic information on all of its stoves, including the Eta. (The DVD may be viewed on Primus's website.) This I found to be mostly marketing material, though it did indicate that a Primus canister, presumably smaller than the one I had, can be stowed inside the pot.
Set-up. Even for a mechanical idiot like me the Eta is easy to assemble; I was able to accomplish this the first time intuitively, before reading the instructions or watching the video. The top of the base plate/burner unit has three small raised notches. The bottom of the windscreen has an open section allowing placement flush to the base plate, and with a quarter turn the bottom slides neatly into the notches. Raise the three hinged pot supports, top with the pot, connect the hose to a fuel canister, and I'm ready to boil. When the pot is centered on the supports there's about one-half inch (~13 mm) space between the top of the windscreen and the side of the pot, and about an inch (~25 mm) of the bottom of the pot is shielded by the windscreen. The wide base makes this a very stable stove.
The frying pan won't fit atop the windscreen, as Primus intended. In bold type in the instruction booklet is a clear prohibition: "Windscreen to be used with Eta-pot only!" So frying or use of a larger cooking pot will not have the advantages of a windscreen or heat exchanger.
The gripper looks to me to be a standard-sized backcountry multi-pot gripper and the tool similar to those available with other Primus stoves (I have two). In the instruction booklet and on its website Primus notes that the insulated storage pouch may be used as a potholder or as a cozy to keep a pot's contents warm.
Fuel. As a canister stove the Eta takes various sized containers of liquid propane/isobutene/butane mix fuel. Primus sells several sizes. In the instruction booklet Primus states that the Eta is intended for use with Primus canisters and warns of "risk" in using other manufacturers' fuel.
Trial run. I fired up the Eta while on vacation in Big Timber, Montana, elevation 4500 ft / 1400 m, in the morning at 50 F/10 C and at dinnertime at 85 F/30 C. On both occasions, with the Eta pot three-quarters full, the lid on, and the valve wide open, I had a rolling boil in just over the two-and-one-half minutes Primus promises. The stove is loud and the flame fierce. I used the Primus cloth (not the pouch) as a potholder to remove the frying pan lid. The stove arrived after the backpacking portion of this holiday, but I did carry the full system, in its case, in a backpack on a day hike. Because I didn't need to carry a shelter or sleeping bag there was ample room and I didn't notice the weight.
* * * * *
This concludes my Initial Report. I have two group backpacks scheduled during the next two months, in Colorado and Montana, both of which should be excellent testing opportunities for the Eta. Check back in late August or early September for first results of field testing and two months after that for my long term report. Thanks to Primus and BackpackGearTest.org for the opportunity to test the EtaPower EF cooking system.
I used the EtaPower EF stove on a two-person overnight backpacking trip in North Texas in early July. Daytime highs were about 80 F (27 C) and nighttime low about 60 F (16 C), and everything was damp from the record rains that swamped us in early summer. My friend and I used the stove to prepare dinner of freeze dried packets enhanced with various Just Tomatoes! veggies, after-dinner tea, morning coffee, breakfast of pancakes and bacon, and tea with a cold lunch. I prepared breakfast in the Primus frying pan; the other uses involved boiling water in the Eta-pot.
I also took the Eta on a seven-day backpacking service trip in late July/early August in the Mineral Creek area of the Scapegoat Wilderness, Montana. Here it was really dry, with temperatures ranging from about 45 F (8 C) at breakfast time to 90 F (32 C) during the day to perhaps 75 F (24 C) at dinner. As often occurs on my service trips our partner organization, the Bob Marshall Wilderness Foundation, arranged to pack our tools, food, and a two-burner propane stove in to our campsite. I had intended to use the Eta to supplement the camp stove, primarily for morning caffeine fixes for the three addicts in our group, but circumstances promoted it briefly to our sole cooking source. When a spill on the way in dented the thread on the propane tank's valve, making the camp stove unusable, the Eta was pressed into service for Sunday dinner and Monday breakfast for nine: On Sunday I made a hot rice dish in a two-liter cooking pot, and boiled hot water for drinks in the Eta-pot and for dishwashing in the cooking pot. Breakfast meant boiling hot water for oatmeal, coffee, tea, and hot chocolate, requiring four rounds with the Eta-pot, each with about 1.8 liters of water, and one with a percolator with about the same amount. The engineer among us fixed the valve on Monday morning, so the Eta returned to coffee and tea duty for the balance of the week, with a brief stint to fry two small trout in the Primus frying pan one evening.
Cooking Strength. When used with the Eta-pot and windscreen with the frying pan as a lid, the Eta boils water as quickly as any backpacking stove I've ever used. None of the coffee runs I timed exceeded three minutes for a rolling boil of 1.4 liters (1.5 qt), at 6500 feet (2000 m) elevation. I achieved excellent results without the heat exchanger too. In Montana we brought water in a two-liter (~2.2 qt) aluminum pot to a boil in four minutes, and the trout cooked quickly in the Primus frying pan. In Texas, using a high flame to warm the pan and then turning down the heat to cook, even with an almost-empty fuel canister our pancakes and bacon breakfast was ready in a very short time. This stove is a powerhouse.
Design. I have been very favorably impressed with the Eta's versatility. Primus put great care into designing this product. Each component contributes to a cooking system that more than suffices for four hungry campers, and several pieces do double duty. The frying pan serves as a lid for the Eta pot. For this task I've found it easier to place the frying pan right side up atop the Eta-pot, as it's easier to remove it with the pot gripper than if I use the more natural upside-down position. The carrying pouch works very well as a cozy; it meant hot coffee while I prepared breakfast on my first trip and it kept the leftover rice warm through dinner in Montana. The cloth that keeps the heat exchanger baffles from scraping the non-stick base of the Eta-pot when the unit is packed makes a perfect potholder. I really like having a dedicated potholder while camping – much more effective and much more sanitary than using a handkerchief or bandana. (I haven't yet used the pouch as a potholder, as Primus suggests, but will do so on my next trip.)
Other details also impress. The rolled lip of the Eta-pot makes it easy to pour boiling water into a cup or freeze-dried food pouch without spilling. The side wall on the frying pan is high enough to keep most spatters and sputters inside the pan and away from the fire. A 110 gram (7 oz) canister of Power Gas (Primus's branded isopropane-butane fuel mix) fits inside the Eta-pot for storage, with room left over for a couple of packets of food and some tea bags. It's early days yet in this stove's life, but the non-stick treatment has worked without fail on the Eta-pot and frying pan.
Ease of Use. As has been my experience with all Primus stoves (which I've used for almost all my hiking career), the Eta is simple and easy to set up and operate. Unless using the Eta-pot, just screw in the fuel canister, fold out the arms, place the cooking vessel upon them, turn on the gas, and hit the piezo. Using the Eta pot requires one more step, fitting the windscreen on the base before folding out the arms. I can easily adjust the flame with the knob on the fuel canister valve, and simmering is as easy as boiling, making the Eta especially effective for my favorite backcountry breakfast, freshly caught trout. The pots are easy to clean with hot, soapy water and a sponge (on the service trip) or bandana (on the overnight).
I have had only one mechanical issue with the Eta. The electrode arm of the piezo bends easily and occasionally sits too high above the stove head to light the flame. I've handled this by checking its position before assembly and bending it down if necessary.
Weight and bulk. What about these, my main concerns in my Initial Report? So far neither has been a problem, though I still find it somewhat incongruous to stow something that looks like a hatbox in my backpack. On my overnight, and the two day hikes mentioned in my Initial Report, I had ample room in my weekend pack (capacity 5200 ci/85 l) for the unit without having to sacrifice any camp or trail conveniences. On my service trip I treated the unit as group gear – I took the stove, others took food, water purification kit, and so on, and I crammed the nested system, inside the pouch, into my expedition pack. A fair comparison of the Eta to the alternatives in my gear closet must take account of the fact that the former includes two cooking vessels that I regularly pack, pot gripper, potholder, and coffee cozy, and gives me about triple my usual boiling capacity. The Eta isn't my lightest choice, but I don't think it's overkill either. This view might change on a solo trip; I hope to address this in my Long Term Report.
What I like:
Easy to set up and
What I Don't:
I think Primus should
include the pouch and cloth in its listed weight.
This concludes my Field Report. Look here for my Long Term Report at the end of October. Thanks again to Primus AB and BackpackGearTest.org for the opportunity to test the EtaPower EF cooking system.
LONG TERM REPORT
October 29, 2007
During the last two months I've added two new applications for the Eta: solo backpacking, to evaluate the system's weight and bulk when I'm traveling by myself; and use of other manufacturers' fuel canisters with the Eta.
I took the Eta on an overnighter in Oklahoma over the Labor Day weekend, clear weather with temperatures of 60-95 F (16-34 C) at an altitude of about 1000 ft (300 m). Having a complete kitchen kit prompted me to pack a small steak for dinner (packed frozen at noon, thawed when I reached camp) that I fried with a bacon strip in the fry pan. Breakfast the next day was hot oatmeal prepared by boiling water in the Eta-pot and adding the cereal and some dried fruit after about a minute. I also tried the pouch as a potholder but found it too large for this task, not nearly as workable as the cloth.
I was blessed with wonderful backpacking conditions on an easy two-night Hill Country backpack in late October. Daytime temperatures didn't exceed 70 F (21 C) during the day, chilly evenings at 40 F (5 C), very light wind, and a full moon. Steak was on the menu again for Friday night, cooked (for two) in the frying pan with a bit of fat cut off and melted for cooking. Saturday night was more traditional backcountry fare, faro cooked with dried peas, carrots, onions, and a beef stock cube, nicely simmered for about twenty minutes in the Eta-pot. We enjoyed pancakes for breakfast on Saturday and oatmeal and fruit on Sunday.
The Eta has picked up some non-backpacking usage too. Twice on day hikes in North Texas I took the Eta in the car and ended the hike at the trailhead with tea all around (for two the first time, four the second). These were typical warm autumn days, high perhaps 95 F (35 C); on the latter occasion the stove did its work in a thunderstorm. I also used the Eta on a fishing day on the Madison River, Montana, in mid-September. This day started out sunny but by early afternoon became blustery and cold (~40 F/5 C) with a couple of heavy rain showers as a cold front moved in. Hot chocolate spiked with bourbon was a welcome treat at the end of the day as we waited for our friends to pick us up. The windscreen on the Primus did its work well; I had the usual short boiling time despite the gusts.
I've used the stove with canisters from MSR and Jetboil. The MSR was by necessity, as I couldn't find a Primus canister locally for my Montana trip. I had a couple of Jetboil canisters at home and used them on my Texas hikes. Both brands had threaded Lindal valves like those on Primus canisters. I detected no difference in set-up or performance when I used the non-Primus canisters. One of the Jetboil canisters was no more than one-quarter full, but the Eta fired up with its usual strong flame. It's tempting to use a Jetboil canister because it fits neatly inside the Eta-pot when the system's packed up.
I didn't really have a problem with storing the Eta on my solo hikes. Both times I took a 5200 cubic inch (85 L) pack, and both hikes were short enough in duration so that there was ample room for the Eta, stored as usual in its pouch in the main section of the pack. The Eta in its pouch is a tight but workable fit in my usual day pack, but takes up much more pack space than the alternatives mentioned below. But even though I tend to overpack and not count every ounce, there are several reasons I expect the Eta will not be my first choice on solo backpacks in future, even on fishing trips when I want a skillet. With a competing heat exchanger cooking system designed for individual use, plus a separate frying pan, I can save about half a pound (0.2 kg) over the Eta, more really since the solo set includes a French press accessory for coffee so I needn't bring a separate coffee maker. The saving in pack space is even more pronounced. If I'm going really light I can use an older traditional lightweight canister stove (also from Primus), or a new wood-burning backpacking stove that I acquired last spring. Any of these alternatives, even when adding extras like a skillet, takes up less room than the Eta, and I get comparable performance from the solo heat exchanger system.
Primus has anticipated this reaction. I read with keen interest the Manufacturer's Comment that Primus posted in connection with this Test Series, to the effect that Primus will introduce an integrated system similar to the Eta that's designed for solo backpackers. Bring on the EtaExpress! (A side note – on its website Primus recently posted information about a new system, called the EtaPower MF, that will be available next spring. I can't tell if this is the EtaExpress or not, but if so Primus promises information on the site "soon.")
Results on other fronts mirror those in my Field Report. The non-stick treatment has held up throughout the test period, though it hasn't been put to the carelessness test, finding out what happens when I leave something on the stove too long and allowing the water to evaporate. That's a happy consequence of the efficiency of heat exchanger cooking – the speedy cooking times mean that I must pay attention rather than attend to other camp chores. All food, even bacon grease, is easily removed after soaking the frying pan in hot water for a few minutes. No component shows any unusual wear; I can't detect any serious scratches or scrapes on the bottom of the pot or frying pan. Now that I'm careful to position the piezo immediately after assembling the stove it has not missed an ignition.
I had hoped to get to the Rockies in October but my day job interfered, so I haven't had a chance to see how this canister stove works at temperatures much below freezing. Down to 30-35 F (-1 to 2 C) I've found no deterioration in performance. I haven't been able to evaluate Primus's claims of fuel efficiency in any systematic way, though a week's use on the Montana trip described in my Field Report didn't exhaust a 645 g/23 oz canister of Primus PowerGas.
When I am backpacking as part of a group – and by group I mean two or more –the Eta will likely be in my pack. Its capacity especially makes it a steady winner. I can boil coffee water for four and have breakfast ready in the frying pan before the coffee's finished steeping in my French press. At dinnertime the Eta-pot's size and the stove's power and efficiency mean easy and speedy preparation of anything from plain boiling water for a packaged meal to a rice dish that requires careful simmering. I can increase capacity by using a larger pot, as I did in Montana when cooking for nine. Or I could add a second Eta-pot, now available as an accessory separately from the system. Using the cozy I can keep second helpings warm while frying trout or other special treat. I like being able to store all my cooking kit in one place in my pack. Taking into account the accessories included with the Eta, its overall size and weight don't exceed the alternatives in my gear closet by much. Yes, I'd save weight with the wood burner, but its boiling time for two liters/quarts of water even in perfect conditions exceeds twenty minutes. Once again betraying my weakness for luxury over counting ounces, I'll take the convenience of the Eta any backcountry day.
The Eta was perfect for the Hill Country trip. Food weight wasn't a particular concern, and this compact system made it easy to enjoy car-camping cuisine on a backpacking trip.
Bottom Line. With the EtaPower EF Primus has moved into heat exchanger cooking without any deviation from the sound design, simplicity, and reliability that have kept me cooking with its stoves for more than forty years. The Eta stove is stable, reliable, easy to set up and cook with, and all components are easy to clean. The windscreen works really well. The stove's power combined with an efficient heat exchanger system make for remarkably rapid boiling, in wind and rain as well as fair weather. All system components are easily stored in one place for ready access, and there's room inside the pot for other kitchen items such as a fuel canister, knife and fork, spatula, and a couple of packets of freeze-dried food. The cozy/storage pouch and potholder/storage cloth have been useful every time I've taken the stove out. Truly an integrated system. Except for my early piezo problem, now manageable, everything has worked as it should without fail. Brå, Primus – well done!
Two Suggestions. Perhaps Primus could figure a way to incorporate a heat exchanger into the frying pan. My frying times have been entirely satisfactory thanks to the stove's robust flame and low profile, but a heat exchanger would increase efficiency and reduce the chance for wind problems. This might make it more difficult to use the frying pan as a lid for the pot, though, and might enlarge the packed size of the system.
The pending introduction of the EtaExpress (or EtaPower MF, or both) prompts me to hope that some pieces of the new systems may be used interchangeably with those of the EtaPower EF.
* * * * *
This concludes my Test Report. My sincere thanks to Primus AB and BackpackGearTest.org for the testing opportunity.
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