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FR: Primus EtaExpress--Rick D.

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  • Rick D.
    Attached, please find my EtaExpress field report. HTM is here: http://www.backpackgeartest.org/reviews/test/TESTS/FR%20Primus% 20EtaExpress--Rick%20D/
    Message 1 of 1 , Jul 5, 2008
    • 0 Attachment
      Attached, please find my EtaExpress field report.

      HTM is here:





      Field Locations and Conditions

      I took the EtaExpress on three backpacking trips: two one-night trips
      in Desolation

      Wilderness and one two-nighter in Lassen National Park. The
      Desolation solo trips were

      between 6,500 and 7,500 feet (2,000-2,300 m), with mild weather on
      one (60 F/15 C) and cold

      (45 F/7 C) and rainy on the other. The Lassen group trip was at 6,500
      feet (2,000 m) and

      brought mild temperatures (60-70 F/ 15-21 C) with was pleasant
      weather days one and three,

      intermittently stormy with wind, rain and hail on day two.

      in hammockland.">>

      Field Performance

      Most of my stove use was heating water for reconstituting food and
      for hot drinks, although

      I also made rice in the pot. A wooden paddle/spatula provides safe
      stirring, scraping and

      serving without damaging the nonstick coating. I've also melted snow
      for drinking and

      cooking water, and the system made quick work of soggy springtime
      snow. Stove setup and

      operation were quite simple and quick in all conditions. Because it's
      relatively tall atop

      the cartridge, canister footing needs to be level and stable or the
      stove rocks, although

      I'm not above plopping it on the soggy ground and firing it up when I
      want hot water,

      "stat!" Lighting via the piezo igniter is trickier at altitude and in
      cold weather than at

      sea level in shirtsleeve weather, but it does still work with careful
      control of the fuel

      flow (too much fuel and it won't light). The partial-coverage
      windscreen leaves the flame

      vulnerable to wind, so a sheltered spot is needed in poor weather.

      snow=handy water.">>

      In the field the stove heats fast, melting snow and boiling water
      quickly. It seems frugal,

      as a standard 220g (7.8 oz) cartridge lasts multiple days, although I
      don't yet have a good

      idea of how many days/cartridge/person to budget for. It's a
      distressingly difficult number

      to determine with any confidence. As with all vapor-feed canister
      stoves, the Eta flame

      becomes feeble with spent cartridges.

      The pot's tiny pour-spout doesn't seem effective in directing a
      stream of hot water into a

      food container or cup, and so far I've not used the miniscule frypan
      lid for anything other

      thanÂ…a lid.


      The EtaExpress makes a tidy package, with a standard canister stowed
      inside the pot, along

      with the burner and windscreen. To avoid damaging the heat-exchanger
      fins, I try to pad it

      in the pack using clothes, etc. It has to go inside the pack, as my
      pack pockets aren't

      large enough to stow it there. I wouldn't necessarily do so anyway,
      as I wouldn't want to

      bash it against a rock, stowing in the pack prevents quick access for
      making a hot drink or

      lunch on the go.

      Wear and Tear

      The EtaExpress system remains in good condition. The pot has
      accumulated a couple minor

      dents and some fins have been flattened (and straightened), the
      burner is heat-discolored,

      but everything else is as new. Importantly, the nonstick coating is

      boils fast enough for


      Bench Testing

      In an attempt to baseline the EtaExpress fuel consumption and
      determine the impact of the

      heat-exchanger pot and windscreen, I ran some water boil tests using
      three options. My test

      conditions were as follows:

      Water volume: 500 ml (17 fl oz)
      Water temperature: 66 F (19 C)
      Air temperature: 90 F (31 C)
      Elevation: sea level
      Wind: < 5 mph (8 kph)
      New 220g (7.8 oz) cartridge


      I tested 1. the complete EtaExpress kit, 2. the Eta pot without the
      windscreen, and 3.

      another pot-an MSR Titan Kettle-with the Eta windscreen. I hoped to
      discover the effect the

      individual Eta components-pot and windscreen-have on efficiency by
      taking them out of the

      system individually. I measured the time to boil for each
      combination, using an immersed

      thermometer probe to stop when the water reached boiling temperature,
      then weighed the

      canister to determine fuel use. Unfortunately, I wasn't able to pry
      any significant

      difference among the three modes. Either environmental variables
      overwhelmed the system

      differences, my scale isn't accurate enough to tease out small (fuel)
      weight measurements,

      or there's no significant difference. Time to boil was similar for
      all three variations, but

      since it's not possible to exactly match the valve setting between
      tests I don't put much

      value on boil times. In all cases I used a moderate flame to maximize
      efficiency. The

      Express burner will crank out a really big flame, if one's so

      My tinkering wasn't for nothing, because I can at least note that
      EtaExpress averaged 0.5 oz

      (13 g) fuel per liter boiled (with a 66 F [18 C] starting

      pot, same result.">>

      Manufacturing Changes

      I've checked out two or three EtaExpress systems in the store to see
      whether there have been

      any changes from my tester. I discovered the pot and/or lid has been
      altered and now the lid

      fits snugly without partly folding the lid handle. The heat-exchanger
      fins are now

      reinforced by a metal ring circling the inside to about half-height.
      This should prevent

      their being crushed completely flat against the pot bottom by
      accident, a

      possibility-however remote-with the pot I'm testing. I view both
      changes as distinct



      The EtaExpress is a slick, easy-to-pack and easy-to-use system. The
      stove burner folds

      small, is fairly light and performs well (lights easily, easy to
      control). The windscreen

      solves the thorny problem of how to get the windscreen up by the
      burner while leaving access

      to the igniter and valve, especially versus the foil screens I
      usually fiddle with on

      canister-top stoves. The pot is a reasonable size for one or two, and
      has the added

      heat-exchanger feature.

      My controlled tests didn't demonstrate much of an efficiency impact
      from the heat-exchange

      pot or windscreen. There may indeed be a difference using them, but
      my little experiments

      didn't reveal any.

      Based on my "investigative shopping," Primus has already addressed a
      couple of issues by

      altering the lid fit and reinforcing the pot fins. My sole question
      at present is whether

      they'd gain better performance by increasing how far the windscreen
      wraps around the pot,

      perhaps halfway or even two-thirds. It would definitely enhance wind
      protection and likely

      efficiency as well.

      Testing Strategy

      I'll continue to use EtaExpress the rest of the summer, likely as not
      extending my cooking

      experiments beyond what I've done so far. Watch for the long-term
      report in two months.


      Many thanks to Primus and BackpackGearTest for the opportunity to
      test the EtaExpress!

      This report was created with the BGT Report Generator.
      Copyright 2008. All rights reserved.
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