Sunday, 3 July 2016

Review: Trangia UL HA 27-7 Cookset with Gas Burner

The Trangia 27 Series Stormcooker is a smaller version of the 25 Series. The Trangia 27 system is suitable to cook for 1 or 2 at a time. In Scandinavia it is called the "StormCooker" for its reputation to keep working in poor weather conditions.

Many lightweight stove systems are reduced to boiling water only, even adjusting fuel flow for simmering functions may be difficult.  Trangia systems are well known for their versatile cooking abilities, ranging to pancakes and pizza. 

What You Get
The out-of-the-box Trangia 27-7 UL HA (ultra light, hard anodised) cookset weighs 720g with the methylated spirit burner.   The kit includes stove base, windshield, 2 nesting 1 litre pots, frypan/lid, pot gripper and strap along with the methylated spirits burner with its lid and simmer ring. The two 1 litre pots and the pan/lid are anodised. The 2 nested pots look identical in size and nest very closely. There is room inside the packed windshield to fit a third pot if Trangia ever manufactured a slightly larger version. No kettle is supplied, but Trangia have one you can fit inside the nested pots (and in a miracle of design also fit the metho or gas burner inside).

Another option Trangia offers is a Multi-fuel Burner.  This has a 0.32mm jet for canister gas and Shellite/kerosene use.  The Primus Omnifuel has a similar looking fuel system but there may be differences in connectors.

Trangia 27 nested pots with a firesteel. A metho or gas burner or gas canister can also fit inside
 This review mainly looks at the Trangia Gas Burner with this cookset. I purchased this 180g Gas Burner from a local shop but I understand it is now unavailable as there is an issue with Australian standards compliance. This compliance is expensive to obtain and the market here for these devices is small.  I understand the Trangia gas burner complies with the prEN 521 (EU and Nordic) and CAN-11.2-M79 (Canada/US) standards.

Trangia Gas Burner product sheet snippet

Two Trangia 27 Systems

System 1  Add an 18cm 73g Multi-disc (lid/strainer/cutting board) ,  10g of 3mm CCF pot and pan cosies and a MYOG foil pot lid for a weight of 803g. A full 500ml (400g methylated spirits fuel, gross 516g) Trangia fuel bottle brings the total to 1,319g.  You can also store 70g of methylated spirits fuel in the stove which is enough to boil 2L with some left over. Add an ignition source. You can pack everything into the nested Trangia 27 system except the fuel bottle.
Trangia 27 secured for packing.

Under backyard testing, the Trangia 27 cookset plus spirit burner used 18g of methylated spirits and took 11 minutes to boil 1 litre of water.  That comes to about 22 boils for the 500ml Trangia fuel bottle.  Getting 20 boil-ups would be a good result and with 2 boil-ups per day, it may last up to 9 or 10 days.
Trangia 27 multidisc lid/strainer/cutting board
I reckon the multi-disc is worth getting as a cutting board and lid.

System 2  For the Trangia 27 cookset plus gas burner subtract the 113g methylated spirits burner and 516g full fuel bottle and replace these with the Trangia Gas burner at 183g and a 363g gas canister. That comes to a slightly lighter 1,246g cook system with 2 pots, fry pan and enough fuel for 5+ days at 2 1L boils per day (see stove test below).
The Trangia Gas burner appears to be strong, tough and very well made.

You can store everything inside the nested Trangia 27 cookset except either the gas burner or a 363g gas canister.  One of these items will need to be stowed separately.

The gas burner has a 37mm jet

The Trangia Gas burner installed on Trangia 27 base.
The burner snap-mounts in to the base. Hard to see in the photo, I rounded over pointy right-angle corners on the burner spring mount with a file.

The Trangia 27 cookset plus Gas Burner combo forms a remote canister stove system.  Since the burner has a pre-heater tube, the canister may be deployed upside down which makes for better performance in sub-zero conditions.

A Comparison with 2 Primus Omnifuel Systems

The Primus Omnifuel is a very good liquid fuel stove which I have used on snow camps with great success.

The Trangia 27 plus gas burner at 1,246g  is nearly 180g lighter than a Primus Omnifuel in Shellite mode with a 2 Ti wide-pot system like the Snowpeak Multi-Compact set. This Shellite system tested at 15 minutes for a 1L boil using 15g of Shellite fuel and weighs 1,424g with a 514g full (400g fuel) Shellite fuel bottle for about 25 boil ups.  The fuel efficiency difference is probably due to the better windshield on the Trangia.

The Trangia 27 plus gas burner is 100g heaver than the Primus Omnifuel in gas mode with the same 2 Snowpeak Multi-Compact Ti pots. This system tested at 11 minutes for a 1L boil using 18g of gas and weighs 1145g with a full gas canister for about 12 boil ups.  So the Trangia has better fuel efficiency and a better windshield for that extra weight.

Stove Boil Test Result

Trangia says the Gas Burner is high efficiency. When I tested the Trangia 27-7 plus Gas Burner at about 18C ambient temperature using isobutane gas only using a low flow rate and aiming for a "minimum gas usage for a result", I was astonished to find it did a 5 minute boil of 1L and used just 8g of gas in the process. That is fast and efficient.  At single figure significance, that makes a usage rate of  96g/h, well under the maximum rating of 150g/h and would give you about 2hrs 20 minutes burn time for a 220g canister.  I've done a few stove tests now and that beats anything else I have done.  This stove combination is a winner for gas fuel efficiency.  If that efficiency is sustained you can do 28 1L boils per 220g canister, however I would expect something less than that in the field.  I can usually get 10 and a bit boils from an upright stove and canister with a windshield. I use a circular reflector to stop the canister from overheating and keep a close watch on overheating the canister by touching the canister from time to time.  Too hot to touch is too hot! At 2 and a bit boil-ups a day that does me for 5 days. 

A second test on the next evening took 7 minutes and used 11g of gas. I used a low heat in the test.

The ambient temperature for these tests was about 18C, using water from the cold tap.

One of the few negative features with this stove is you cannot see the flame while the pot is in place. So either lift the pot or go by sound when adjusting the flame. Suggestion to Trangia: I wonder if future gas regulators might possibly have small dial gauge.This could be a simple fixed marked ring.

On a field trip at 1,700m, this system prepared dinner and breakfast for two. A bit less than 2L was boiled at dinner plus a few minutes of simmering. About 1 1/2 litres of water was boiled at breakfast. I used a low heat setting and a total of 38g of gas was used.  This works out at a very low 11g of gas per 1L boil or 20 1L boil ups from a canister. That is pretty awesome.

So the evidence is that Trangia's claim of high efficiency is no marketing hype but fact.

Do Aussie bushwalkers need an inverted canister gas stove? I would say, in the snow, yes, but you may get by if you use huts or procedures to keep the canister warm. However it also gets sub-zero in alpine areas in summer!

Low Temperature Function

The gas burner has a pre-heater loop and can be used in "inverted canister mode" for below 0C conditions, which occurs frequently at altitude (above 1000m) in winter in mainland Australia and less frequently in summer.  Below 0C the Isobutane won't evaporate, so it has no vapour pressure, so only the propane is gasified (down to -40C) pressurising the canister contents and burnt off.  Unfortunately, this constituent of the gas mix is only about 20-30% of the gas in the canister and once this is burnt the residual liquid isobutane will just sit there with no vapour pressure to expel it from the canister.  So it is necessary in below 0C conditions to invert the canister before this happens.  The vapour pressure formed by the propane gasifying then pushes out the mixed liquified gases, heating it through the pre-heater loop to expand and gasify when it passes the jet and then igniting. In this way, the propane proportion of the contents remains constant and enables the complete exhaustion of the canister by providing pressure at sub-zero temperatures above -40C.

I have operated an upright gas stove using isobutane at -2C to 0C on a couple of occasions and found it was sluggish, using about twice as much gas over a much longer time to achieve a boil.
Trangia 27 windshield and gas canister attached to base
Ready to be boiled

How cold does it get in Australia?

In mainland Australia it is unusual to get temperature reports below -10C.  Major caveats apply here and unusual does not mean never. The national lowest temperature record  was -23C in 1994 at Charlotte's Pass, Kosciuszko National Park (KNP).  A temperature of -19.6C was recorded there in 2010 and in August 2016 -10.4C was reached at Thredbo.  This was the only reported sub -10C minimum reading for all of Australia over that year. However note there are many very cold camping locations that are not reported, such as frost hollows under clear skies, wind chill effects etc.

I quote the following further weather record lows to support my contention that sub -10C is unusual. The record low in Tasmania is -13C in 1983.  The record low in Victoria (Falls Creek) is -11.7C in 1970.  It was also -10.5C again at Falls Creek back in 1974.  The Queensland record low is -10.6C in 1965.  All the sub -10C record lows are older than 20 years.  There are no records of sub -10C temperatures in WA, SA or NT although desert nights can be very frosty and sub-zero.  While the record minimums gives us an idea of low end temperature patterns, it does not mean minimums have not reached below -10C in recent times.

So what about the monthly minimums for the last few years? For 2015 I found 9 reports of sub -10C minimums (Jun-Aug), mostly in KNP and a couple in Tasmania.  2014 had 10 reported sub -10C minimums (Jul-Aug), again mostly KNP.  2013 had 6 reports. Typically these temperatures were just below -10C to -13C. Some readings were for the same day from nearby stations. We can say it is not unusual that in any year that the KNP region will report a sub -10C minimum temperature on at least 1 occasion, but it is also fair to say that for any random day of the year that somewhere in Australia reports a sub -10C minimum is unusual.  There were no Victorian sub -10C readings (which we may expect from Hotham or Falls Creek) for any of the years 2013 - 2016.

It is also worth noting sub-zero temperatures (around -4C) in KNP in December is not unusual, so pre-heater gas stoves are not just for snow camping in winter.

Using a striker and flint to light the burner inside the windshield can result in a small whoomp-style explosive ignition, so avoid placing hands inside to ignite. I suggest removing the windshield to light or else use long matches - which can be found with BBQ supplies in shops. A long piezo igniter might work but I don't like these as I don't trust their reliability to work in all conditions.

The Trangia frypan can be used as a lid. There is high potential for heat efficiency here.

The Trangia 27 with Gas Burner delivers very good efficiency as well as outstanding cooking versatility. Weight difference is also not significant with other remote canister stove systems which usually have ad-hoc windshields that require constant attention. Upright canister stove systems may be lighter but are even more unstable and frequently tip over with boiling contents and should never be used without canister legs or mounted and fixed to a piece of board.

The Trangia 27 with Gas Burner is an excellent solo combo kit for snow camps and high wind-exposed camping and hard to see what could beat it for a 2-person stove system in or out of snow.

It is a bit more bulky and heavier than single pot upright canister stove solutions but is more versatile, much more stable and safer, especially for inexperienced bushwalkers,  and has become my goto cook kit.

The Trangia 27 with gas burner gets my 5 stars ***** award.

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