Reviews > Cook and Food Storage Gear > Stoves > Primus AB ETA Multi Fuel Stove > Test Report by Ralph Ditton

                          Photo courtesy of Primus                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          

• Burner Base
• Windscreen
• 2.1 Litres EtaPower pot with heat exchanger
• Frying pan/lid
• Spondonical (Billy Grip)
• Ergo Pump
• 0.35 Litres fuel bottle
• Multitool
• Storage Bag

set of instructions in a manual form. There are instructions in English, Swedish, Finnish, Norwegian, Dutch, Italian, Spanish, Portuguese and Danish.

The English instructions consist of two A4 size pages. On the front of the manual are a series of schemata (diagrams) to assist in assembling the stove with lines leading from a numeral to a part on the stove. The manual instructs which jet to use for which fuel, advice for safe use, how to assemble and use the stove with LP gas cartridges, when using a fry pan or large pots, assembly and use of the stove with liquid fuel, maintenance and troubleshooting.

In addition to the above components, there was a carry case, tube of silicone grease, two jets for burning of different fuels and a cap for the fuel bottle when the stove is not in use.

This stove is a multi fuel unit which can burn LP Gas with a butane/propane mix or isobutane using the jet stamped 32. Industrial petrol such as Primus Powerfuel, MSR White Gas and Coleman Premium Blend, unleaded petrol but NOT leaded petrol using the jet stamped 28. Finally, using the jet stamped 22 paraffin/kerosene can be used. At a pinch even diesel.

The drawback with paraffin/kerosene and diesel is that they burn with a smoky flame, can be difficult to preheat and require regular cleaning.

Using unleaded petrol is risky because of the extreme volatility and it contains additives that will leave more deposits in the fuel system, again requiring regular cleaning.

                                                                            

The Parts
Base Plate Holder
The base plate holder is 160 mm (6.2 in) in diameter and 30 mm (1.2 in) high. There is a hole cut out of the plate to accommodate the burner. It is shaped roughly like a light bulb. Around the periphery of the hole are three pot stands that fold down for packing. The top of the arms have a serration to help grip the base of the pot and prevent any sliding.
On just over a third of the side, there is a series of sloping vents to allow air to be drawn in under to the burner.

Underneath the base plate holder is a slot and bracket. This is where the burner bracket is mounted. One end of the bracket is inserted into the slot and the other end is then pushed into the slightly springy bracket which locks the burner bracket into place.

The Burner unit
The burner head is 39 mm (1.5 in) in diameter and sits on top of a brass upright of 22 mm (0.86 in). At the base of this upright the bracket that locks into the base plate holder is located. It sweeps up from the base in an dihedral fashion.
Feeding into this upright is another brass injector tube 60 mm (2.3 in) long and a diameter of 11 mm (0.4 in). About the halfway mark there are four holes around the circumference covered in a fine wire mesh. These holes are the air intakes to assist with the burning of the fuel.
In between the mesh and upright tube is a swiveling base plate. This plate rest on the surface of what the stove is being used on and helps support the burner head.

Leading away from the injector tube but curving back and skirting the periphery of the burner head is a thinner brass preheating coil. Where the preheating coil and injector tube meet is where the jet is located and this is where the change of jet takes place depending on the fuel being used.

The flexible hose leads away from the preheating coil to where the on/off knob is. The hose is 300 mm (11.8 in) long.
The knob has a lot of play so it should be able to achieve a desired flame height. At the other end of the control knob is where the fuel bottle and/or gas canister attach.

The Windshield
The windshield has a diameter of 208 mm (8.1 in) and a height of 60 mm (2.4 in). Most of the base is cut out so that the burner unit can heat through it and the pot support arms on the base plate holder can be folded into position to support a pot. The sides are solid and this is where Primus has its wording "PRIMUS EtaPower MF" around the perimeter.

The Pot
The pot has a diameter of 102 mm (7.5 in) and a height of 95 mm (3.7 in) excluding the heat exchanger. The heat exchanger is bonded to the base of the pot and measures 150 mm (5.9 in) in diameter and 15 mm (0.6 in) in height.
Inside the pot there are markings from 0.2 to 1.8 litres (0.2 to 1.9 quarts) with graduations at 0.2 litres (0.2 quart).
The pot is coated with a three layer titanium non-stick material and the pot itself is made out of hard-anodized aluminium.

The Frypan/Lid
It measures 205 mm (8 in) in diameter and 34 mm (1.3 in) deep. It is also made out of hard-anodized aluminium and the inside is coated with the three layer titanium non-stick material.

The Fuel Bottle
The fuel bottle is short, measuring 130 mm (5.1 in) long and has a diameter of 66 mm (2.6 in). The maximum volume that it can contain is 300 ml (10.6 fl oz). There are two maximum filling lines, one directly opposite the other and are in line with the top of the PRIMUS label.
The bottle is made out of seamless extruded aluminium and lacquered inside to provide protection for the bottle. The connection thread is standard.
When being used as a storage bottle for fuel there is a cap that screws into the neck thread. Just below the gasket there are two holes in the thread directly opposite each other designed to help break the seal when unscrewing the cap.

The Fuel Pump
The thread that connects with the fuel bottle is off set at a slight angle so that the stem reaches into the area where the bottle curves from a side into the bottom of the bottle to obtain the maximum fuel available.
To pressurize the bottle there is a pump rod with a very generous thumb rest. Two fingers grip the shaped stem with the thumb resting on the top. It is a matter of lifting up with the fingers and pushing back with the thumb.
Running along side the pump rod is the fuel rod which leads into a plastic housing where the pump connects to the fuel line by means of a swivel coupling.
Stamped on this housing are the words "ON" and "OFF". The "ON" must be showing in the face up position when the stove is in use. To close down the stove and empty any fuel in the fuel line, the bottle is rotated 180 degrees so that the "OFF" text is pointing face up. When the flame has gone out and only air is going through the jet then the system can be turned off by turning the control knob clockwise as far as it will go.

The Jets
There are three jets supplied with this stove. At the beginning of this section I have mentioned what type of fuel is used with what jet.
The jet is located and housed at the end of the preheat coil leading into the brass injector tube. The jet looks like a stretched out dressmaker's thimble for a doll and is 18 mm (0.7 in) long and has a diameter of 10 mm (0.39 in).
Inside the jet for the last 7 mm (0.27 in) it is threaded for screwing onto the end of the pre heat coil. On the exterior there is a hexagonal section half way down the shaft for use by the multi tool to tighten or loosen on the pre heat coil.
On the base of the jet which is flat is stamped two numerals. Between the two numerals is an extremely small hole. This is the jet hole and the numerals indicate what size the jet hole is.
So, the numerals 22, 28 and 32 are really 0.22mm, 0.28 mm and 0.32 mm (0.00866 in, 0.01102 in and 0.01259 in).

The Multi tool
It measures

• Three layer Titanium non stick surface
• Excellent stability
• Can use LP gas and not just liquid fuels
• Potential high efficiency rate over 80%
• Very fast boil time
• Compact with low weight

• Instruction manual bit short on detail for assembly and drawings in Fig 2 could be bigger with more detail
• Reference to numerals with no drawing of them or a schema with an exploded view
• Lack of clarity regarding using the stove with the cleaning wire in the fuel pipe
  

As I have never operated a multi-fuel stove before, I was very apprehensive. I read the instructions over and over to make sure that I had it right before striking a match.

My first firing of the stove at camp at 7.00 pm was approached with some trepidation as I was using petrol (Coleman Premium Blend Fuel to be precise) and it was getting dark.

I changed the jet to no. 28 (for ease of understanding in lieu of 0.28 mm [0.00866 in] hereinafter I will use whatever no. for all jets) under headlamp which is the one for petrol/gasoline. The no. 32 jet was screwed on very tight during the initial assembly and I had some difficulty in removing it. I was very worried about damaging the fuel pipe as I had to hang onto it for leverage. Fortunately, nothing adverse happened and the jet was removed after the initial resistance was overcome.

I filled the fuel bottle up to half way, pumped the bottle eighteen times to pressurize it, opened up the valve for a very short time as I noticed fuel spilling onto the foot under the brass injector tube. Heavens, I have a leak. I checked all of my connections to make sure that they were all correctly connected. Wiped up the leaked fuel and reopened the valve. Same thing happened. Fuel dripped onto the foot again. I turned it off and had a think about it because all of my connections were sound. Then the penny dropped.

In the injector tube, there are four air intake holes that go around the circumference. Of course some fuel is going to leak through the bottom air intake hole and the foot at the bottom was really a fuel tray to catch the leak. So I lit it and was greeted with a large flame that burned from the burner head and the tray.

                                    

There was absolutely nothing in the instructions about fuel dripping into the fuel tray. It does not even get a mention in the schemata (drawings) on the front page.

The pan of fuel burnt out and I heard the "crack" which indicated that the pre heating process was a success. I then opened up the valve but there was no flame left in the burner head so I turned the valve off. I then lit a match, put it to the burner head and opened the valve again. Success, a big blue flame with a lovely roar.

                                    

For my first try I only boiled water, a 1 litre and this took about six minutes.

I was very surprised at the amount of black soot on the heating tube, under the burner head, base of the pot and pot support. It wiped off very easily.

My confidence to relight the stove from a cold start jumped exponentially.

Later in the evening I then thought about getting tea ready. I was only going to boil water again for my dehydrated meal.
As I still had some petrol still left in the bottle I used this again.

Yes, the fuel filled up the pan and I made sure that it was as level as it could be. The boards of the table were a bit uneven in that some had a bit of a convex curve on them, or were a tad thinner than the boards alongside.

At 8 pm when I started to get my dinner ready, the outside temperature was 30 C (86 F) and the wind had swung around to SSW at 12 knots. This meant that I had a fair bit of wind blowing in on me. It took six matches to get the fuel ignited for the pre heat. I did not hear a "crack" to indicate that the pre heating was successful. I went by the indication that the fuel in the fuel tray had burnt away, so I opened up the valve and immediately the vapours ignited indicating a successful pre heat. It was a welcome sight.

The water (1.4 litres) took seven minutes to boil and I had the windshield on.

I then added the water to my dehydrated packet and let it sit for fifteen minutes to rehydrate.

                                    

After tea was consumed I decided to make myself a cup of tea about forty five minutes later.
I still had enough water left in the bowl and it was still warm but needed to be brought back to the boil. This I did and the water only took three minutes to come back to the boil. However, I needed to pump the bottle again because when I opened the valve to light the burner head for the pre heat there was no fuel there. The pressure from the two previous boils had gone. I pumped it twelve times.

Fuel consumption after the three boils was very impressive. I had only filled the bottle to about halfway and when I finished for the night I had around a third of a bottle left. My initial impression is that it is very stingy with fuel consumption.

In the pre-dawn morning I had a change of fuel. I used gas. First I had to change the jet back to the no. 32. This was much easier as I had only put slight pressure on the no. 28  to lock it into place. Then I cleaned off the soot.

When I opened up the valve to let the gas flow I was met with a small spray of residual petrol. I ran the gas for a few seconds to clear the line before igniting it. The gas ignited first go.
The temperature at the time was 22 C (72 F) and the wind was blowing E at 15 knots, but I was better protected by the three sided hut.

Again, I only boiled water for my morning cup of tea and the water (1 litre) took about seven minutes to boil. The gas burned cleanly and there was no soot residue on the stove.

                                    

For my next trip of two nights and three days I exclusively used gas.
The location was in the lower central wheat belt in the very tiny township of Bullaring. The vacant home where I stayed had no furniture or working stove. For all intent and purposes, it was just like a camp hut along the track.

Cooking was done on top of the old non functioning cast iron wood stove.
Apart from boiling water for our cups of tea, I also boiled water to cook Gnocchi for three minutes.
I was very pleasantly surprised at how quickly the water boiled and I was boiling about 1.4 litres each time.

For a different type of cooking, I used a large frypan to cook bacon, eggs and tomatoes for breakfast on two occasions and of an evening steak. The Gnocchi was then frizzled up on the frypan after being boiled.
I found it really hard to achieve a simmer. The best I could get was a low flame that still licked the bottom of the pan. Despite this, I still achieved a well cooked meal that my walking partner and I were happy with.
In fact, all of our meals cooked in the frypan were done without any burning of the food despite our futile efforts to really simmer.
The frypan sat reasonably comfortable on the pot holder arms. One of the arms would not lay perfectly horizontal so that all of its top serrated surface did not made contact with the base of the frypan. As long as I was aware of this, I placed the pan a bit off centre for balance and an allowance for the handle hanging out to the side.

                                         

                                   
As per the instructions, I did not use the windshield when using other vessels not supplied by the manufacturer.

My final trip over the test phase was to Thompson Cove in the Nuyts Wilderness for four days. The campsite is at an elevation of 10 m (32 ft) and some 500 m (546 yd) from the ocean.
Temperatures ranged for a daytime high of 32 C (90 F) to a cool 18 C (64 F) of an evening when cooking.

On this trip, I only boiled water for my cups of tea and to rehydrate my meals.

As I still had the gas jet on the stove, I used it for the three days until it ran out then on the final evening and next morning I used petrol. I changed the jet for this.

Whilst using the gas I experienced no problems. I was able to achieve a reasonable simmer to conserve gas usage and I was in no hurry to boil the water. Due to the pot size, I was filling it up to boil water for other members of my group. They were impressed with the speed at which the water boiled in comparison to their gas stoves.

                                    

For my final evening meal, I cleared an area to have bare earth for the petrol. Changing the jet was not a problem although I had to get a younger member with good eyesight to check if I had the right numbered jet.

I filled the fuel bottle to half way and pumped the fuel pump eighteen times.

When I went to turn on the fuel flow to fill the heat pan nothing happened that I could see. No fuel went into the heat pan but I could smell fuel. A very quick look around the fuel line and bottle led to the discovery of three fine jets of fuel spraying out between the O ring on the cap and bottle. The three jets came out of the same area. I gave the cap a bit more of a twist to ensure that it was properly sealed. I did not notice any more fine spray. I then wiped down the area and the stove equipment as I did not want to accidentally start a fire in the surrounding area as it was a total fire ban period. This took a little time.

With concerned members of my group looking on, I then opened up the fuel flow again and had success with the fuel flowing into the fuel pan. I ignited it with a match.

I did not hear any "crack" to indicate that the fuel line was ready so I waited until the fuel in the fuel pan had burnt out before lighting the burner. It worked first time with a nice steady flame.

At the completion of boiling the water, I made the mistake, which I realized straight away, of not turning the bottle over so that "Off" showed on the fuel pump. I just turned it off at the control valve. It turned off ok. To remedy the situation I re lit the burner head after turning it back on and then closed it down correctly.

In the morning I again used the stove with petrol without any problems. I had left it out in the open all connected up overnight.

The base of the pot had a large amount of carbon soot on the base inside the heat exchanger. It was around 1½ mm (0.06 in) long.
Around the vents on the burner there was a film of carbon soot also which wiped off easily with a tissue.

Summary
This stove with its 2.1 litre pot is just too big for one persons needs as it takes up a lot of space inside my backpack. Where it excels is for two or more people. I ended up using the pot for two and sometimes three people to boil water for.
In the future if I know that I will be boiling/cooking for two or more people then I will share the load with them in some form or other, be it other equipment or food. One of the party is going with me on a seven day walk later in the year and he suggested that "the royal we" (meaning me) take the stove for both of us. There is definitely going to be a trade off to compensate for space in my backpack.

The other likes and dislikes remain the same as outlined in the Initial Report.

The campsite sits at an elevation of 83 m (272 ft) amongst Banksia trees on top of a large sand dune that has shrubs, grass and wildflowers.

On the first occasion the weather was hot and dry around 28 C (82 F) on arrival with the wind coming from the ESE at 13 knots.

On each occasion that I used the stove to either cook meals or boil water there was always a wind factor ranging from  10 to 13 knots. I had to use on occasions some equipment to act as a wind break because the wind would gust up to 19 knots.

For one breakfast I ended up going inside the shelter to use the stove to get out of the wind and I still had to use some equipment to act as a wind break. It was a bit more sheltered than out in the open.

The fuel used on each occasion was Coleman Premium Blend Fuel, a petrol blend that claims to burn cleaner. Well I still got soot on the stove burner, tubing, pots, priming pan and base plate holder. Most of it wiped off relatively easily with a damp tissue. Note the soot on the burner in the photo below.

                           

I found that using the Coleman mix, it was very slow to cook our meal of Pork Belly strips so my friend moved the frypan to a gas stove to finish them off whilst I boiled up the vegetables on the Primus. This it did very well.
The frypan can just be seen to the right in the above photo on the gas stove. The problem appears to be the concentration of the flame. It does not spread out far enough to give an even heat to a frypan with a base of 25 cm (10 in). Bear in mind I was cooking for three people that is why I needed a big frypan.

                           

I ran into the same problem at breakfast time when trying to cook bacon for three. It took 

The tomatoes cooked in time with the bacon so we were not waiting for one to finish and the other to get cold.
Having a smaller base made all of the difference to the cook time of the tomatoes on the Primus.
                                 
                             

At no stage did I use the supplied windshield because of the large pans being used. I did not even put the windshield on for the supplied pot to boil water to make cups of tea. I just used equipment at hand to block the wind.

On the first occasion in this test period I did not have any issue with fuel coming out through the cap under pressure. I only half filled the fuel bottle and pressurized it by giving it fifteen pumps.
I suspect that when I had more fuel in the bottle and I pressurized it, I may have slightly over pressurized it causing fuel to jet out around the seal of the cap.
I only had to re-pump the bottle twice between lightings and all of the fuel was used up. All together I had five firings of the stove on the half a bottle of fuel. It was used to boil water twice, cook vegetables and part cook two main meals, tea and breakfast that were about 50% cooked.

I would estimate that the total burn time for half a bottle of petrol to be around 1¾ hours.

At home I gave the stove a good clean up to remove as much soot as possible. I unscrewed the fuel line from the copper pipe injector tube and used the cleaning wire in the fuel tube to remove any carbon deposit inside.
There was very little soot. I wiped the cleaning wire and only a small stain was evident on the cleaning cloth.
The jet got a good poke with the multi tools spike to make sure that it was clear.

Pulling the fuel line and jet apart and reassembling them is a very easy task. I had absolutely no trouble at all and I did not have to exert much pressure on the injector tube when unscrewing the jet off so there was no danger of bending it out of shape.

The next occasion at Prickly Bark my walking friend and I had wonderful rain. A rarity. I did the cooking inside the shelter on the inside table. The location received a total of 6.4 mm (¼ in) from 5 pm to 4 am. Just a steady light shower. Absolute bliss after a long drought.
Wind changed from SSW to SSE when cooking the evening meal and it was coming in at between 4 and 5 knots. I did not have to use a shield to block the wind and the background rain added to the ambiance of the cooking process.

Again I used the Coleman fuel and only half filled the fuel bottle.
No leaks occurred when the fuel was under pressure.
I cooked rump steaks for two and then heated through par boiled potatoes for the meal. Salad was added for the vegetable/greens content.

Reviews > Cook and Food Storage Gear > Stoves > Primus AB ETA Multi Fuel Stove > Test Report by Ralph Ditton