What is the most important precaution that I should take once I have activated the heater?
  • The heat generated is felt in a few seconds and steam will be seen. Do not burn yourself. Once the heater has been activated, place it immediately on the polystyrene plate and then back into the box. This will insulate the meal and help the heater to work more efficiently.

How does the heater work?

  • When water is added to the heater sleeve, it reacts with a mixture of magnesium iron alloy and sodium chloride (FDA approved food grade additives). This generates heat and steam and is scientifically known as an exothermic reaction.

Is the chemical reaction safe?

  • Yes! The only caution is to avoid spilling the hot water that is inside the heater sleeve or holding the heater sleeve immediately after activation because both are very hot.
  • An activated heater produces heat and steam. The chemical end product is magnesium hydroxide. This is a common antacid frequently prescribed by doctors.

If the end product is an antacid, does this mean the product could be ingested without effect?

  • No! The heater and its by-products are not for human consumption.
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    Is the heat reaction similar to the small pouches that we buy to keep our hands warm?

  • No! The reaction is more intense and reaches very high temperatures (up to 83°C or 178°F) in only a few minutes. The heat is maintained for about 30 to 35 minutes. After that it gradually cools down.
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    Once I have activated the heater by adding the water to the sleeve, do I close the sleeve to obtain better heat?

  • No! Fold the heater sleeve once as shown on the instructions. Do not attempt to reseal the heater sleeve. The steam must be allowed to escape.
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    The heater sleeve was accidentally pierced. Can I still use it?

  • No! You should not use the heater but you must carefully activate it with water before discarding. Be aware that activating it generates heat and steam.
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    Is this technology being used elsewhere?

  • Yes. The technology was first introduced during DESERT STORM (1992) to heat the US military meals known as MREs. In 1998, 28 million heater sleeves were used by the US military.
  • Since 1997, the military (MoD) in the United Kingdom began purchasing heaters and in early 1998, the Canadian military purchased a quantity for trial purposes.
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    I have seen a similar heater before when I was in the American military. Are these the same?

  • If you were in the American military before 1996, then the answer is no. The present heater is a more advanced version of the first heaters introduced during Desert Storm. In 1991, the heater device was a solid, cindered pad in a very narrow bag. Since 1996, the new design is lighter, more flexible, takes less water to activate and generates more heat. It is made up of granules of Magnesium coated with Sodium Chloride and incorporated in a semi-permeable membrane and inserted in a wider bag.
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    How hot does the food get?

    • If the food is kept at normal room temperature and heated with the heater, the food should reach 80°C or 178°F in approximately 12 minutes.

    If we refer to the performance data sheet, we will note that 300 g of water will reach the following temperature: 

    Starting temperature  After 12 minutes using the heater 
    4°C or 44°F 76°C or 168°F
    28°C or 84°F 83°C or 178°F

    (Freezing point = 0°C or 32°F Boiling point = 100°C or 212°F)

    How long will the heat last?

    • The heater will generate heat for approximately 35 to 40 minutes depending on the ambient temperature.

    Can I use the heater for other purposes after the meal has been heated up?

    • The heater will keep its heat for some time and can be used for body warmth. Care should be taken if there is any water inside for it might leak out and burn you.
    • Normally, fifteen (15) minutes after the heater has been activated, the water has been absorbed by the heater itself or has evaporated as steam and only dry heat is left.
    • There is enough heat left after 12 minutes to warm up a cup of liquid.

    Can I use the heater to heat water for a hot drink?

  • The heater was originally designed to heat the meal pouches. However, it can be used to heat up water for a hot drink as well. The ideal method is to use a ½ liter Platypus or a ziplock bag filled with approximately 1 cup of your choice of liquid (water, milk, etc.). If used with a new heater, 300 g of liquid will be at 83°C or 178°F in approximately 12 minutes.
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    What else could the heater be used for?

  • In winter, for survival conditions, water may be difficult to find. Take a quantity of snow, place in a large plastic bag. Activate the heater and place under the bag of snow allowing the heater to vent the steam. The snow will be melted.
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    Can the heater be used more than once?

  • The answer should be no but we have noticed that on numerous occasions, the water has not infiltrated into all the heating elements inside the membrane. By adding approximately 1 tablespoon of water after 35 minutes, the heater can be reactivated. This heat is great to warm yourself with or to warm a sleeping bag.
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    Is it safe to put the heater in a garbage container?

  • After use, dispose of all the elements of HOT PACK® whether it be the aluminum food pouch or the heater or the heater sleeve as you would any other refuse.
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    Is the heater and the heater sleeve recyclable?

  • Yes! Both the heater and heater sleeve are recyclable but they are not biodegradable.
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    If I do not use the heater because I did not need it, can I just throw it out?

  • The heater can be used at any time and is safe to keep sealed in the sleeve. However, always activate the heater with water before disposal.
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    Can the heater be used to heat the food pouch if it is frozen?

  • The heater was not designed to heat food from frozen but will effectively defrost and warm it through in about 30 minutes. If you want a meal at 83°C or 178°F, a second heater must be used.
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    Can I use ordinary water to activate the heater or is the water in the sachet specially treated?

  • The activating sachet contains ordinary tap water. The important thing is not to over-saturate the heater with water. The sachet contains 40 ml (1.5 oz.) of water. If you use other water add only to the fill line as shown on the sleeve.
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    If I am in a sailboat and want to use salt water, will that work?

  • Yes! Any liquid would activate the heater.
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    Are there any toxic elements to the heater or heater sleeve?

  • No! Not to our knowledge.
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    Must the heaters be stored in a special room?

  • The heaters should be kept in an area that is dry and away from open flames. The temperature of the room is not important.
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    Are you saying that the heater could be stored in a cottage that has no heat and therefore very cold? Would it still work?

  • The heater is not affected by temperature.
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    Can the heaters be affected by humidity in a room?

  • No. The heaters are in a sealed sleeve. However, the heater sleeves should be kept away from any contact with water.
  • If the sleeve is damaged then you must activate the heater with water and dispose of the heater/heater sleeve. Care must be taken because of the steam and heat being generated when the heater is activated.
  • If you open the heater sleeve and decide not to use it immediately, humidity can get in and the heater might not function to its full capacity. It is considered inadvisable to open the sealed sleeve and not use it immediately.
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    How many heaters can be activated at one time if we are in a confined space such as in the cabin of a truck (6' x 6') or in a mine shaft?

  • The main consideration is not the size of the space but ventilation. A minute amount of hydrogen is given off. This displaces oxygen. That is why we say "Activate the heater in a well-ventilated area". There are, however, no toxic fumes.
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    What is the sweet smell that we detect when we activate the heater?

  • The smell is magnesium being activated and is in no way toxic. All the ingredients in the heaters are FDA food grade standard.
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    How much hydrogen is given off?

  • A trace amount mixed with steam.
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    An hypothetical situation: "There are 15 men inside the cabin of a fire truck. It is winter and the doors are shut to keep in the heat. How many heaters can be activated at one time?"

  • Make sure there is plenty of ventilation. By doing this, there is no problem in activating 15 meals (one for each of the men). Always activate the heaters in a ventilated area.
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    The meal did not seem to get really hot after 12 minutes. Why?

  • Make sure the heater is placed UNDER the meal before activating with water. If the heater is on top of the meal, the water will not make contact with the heater and therefore no heat will be generated.
  • Equally, if during meal insertion, the heater has been bunched up at the bottom of the sleeve, it will not work as efficiently. MAKE SURE THE HEATER STAYS FLAT UNDER THE WHOLE MEAL
  • It is also possible that the heater and meal inside the sleeve were not kept reasonably flat initially (first 30 seconds). The heater needs to absorb the water through each membrane and heater element to obtain maximum efficiency.
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    Is the heater affected by altitude?

  • No! In October 1997, a climber from Vancouver, British Columbia activated the heater at 25,350 feet on Mount Everest. He was delighted to note that it was not affected by the elements. As you are aware, it is extremely difficult to light a fire or stove at high altitudes because oxygen is required. This is not so for the heater. Sadly, the team had to return to base camp because the weather was ferocious. No one made it to the top! 
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    With normal cooking stoves, cooking time doubles every 5000 ft of elevation gain. How does the HOT PACK® heater compare with this? 

    • The HOT PACK® heater does not rely on oxygen in its heat process. The Magnesium & Sodium Chloride mixture works at any altitude once water has been added.