Last Updated on April 9, 2023 by Lisa Vargas
Have you ever had a chance to try meals-ready-to-eat (MREs)? MREs are a popular subject in the prepping community because of their long shelf life, and if they are good enough for the military, they must be good enough for us right?
But the question that always seems to come up is “how does an MRE heater work?” Today, I want to answer that and provide step by step instructions for you to help out!
How Does An MRE Heater Work?
A flameless ration heater (FRH) works by adding a small amount of water to activate the exothermic chemical heater that is provided with every MRE package. The ration heater contains magnesium metal, combined with some salt and iron, which combined with water, heats up the MRE to temperatures up to 100 degrees Fahrenheit.
Using The Flameless MRE Heater
There are actually two MRE heaters now in circulation that can be used. The newer, and considerably safer version is activated by air. The older version uses water. I want to make sure I cover both flameless MRE heaters that comes in the pack. Again, it can seem a little strange for us civilians who have never used it before. So let me make sure I go over how both of them work.
How Does A Flameless Heater Work?
Now before you test out the flameless heater, you need to understand a few essential things. Back in the 90s, most MREs came with flameless heaters that used water for their activation.
These older flameless heaters contain a magnesium-iron heater, which activates an exothermic reaction as soon as it comes in contact with water.
It starts producing enough heat to reheat the food and make it eatable in a while. However, keep in mind that during the reaction, hydrogen gas is produced. Hydrogen is an extremely flammable gas that can cause a disaster if exposed to open flames.
In contrast to old flameless heaters, scientists came up with a new and better solution. The modern MRE flameless heaters don’t rely on the addition of water anymore. It uses air to trigger the reaction and heat the food.
Since the newer MRE heater doesn’t produce hydrogen anymore, this makes the heater pretty safe for all kinds of situations. Apart from that, it allows the soldiers on the field to reserve their water.
Depending on the date the MRE was packaged and the manufacturer, you may get a new MRE heater that uses air to heat instead of water.
How To Use The Older Flameless MRE Heater
Below I wanted to quickly outline how to use the flameless MRE heater that is activate with water, just in case you’re a little confused by it.
Step 1: Remove the Meal pouch from the cardboard box.
Step 2 Open the top of the heater bag simply by tearing the top of the plastic wear instructed.
Step 3: Place the MRE pouch inside the heater
Step 4: Carefully add water to a marked point then fold over the top of MRE heater pouch.
Step 5: Put MRE with heater into the cardboard sleeve provided.
Step 6: Wait for 10 to 15 minutes for the MRE heater to heat the contents of the package. The package can heat up to 100 degrees Fahrenheit, so be careful when handling plastic packaging!
Step 7: Remove the pouch of MRE, and it will be ready to eat!
How Does The Air-Activated MRE Heater Work?
Since approximately 2016, a newer version of the MRE heater was released. According to Army officials at Natick Soldier Research, Development and Engineering Center, “this new approach to heating and advanced technology aims to lower cost, weight, and logistics burden of chemical heating technologies.”
The air-activated heater has a cool peel-away layer that will allow the air to infiltrate the holes of the foil layer on the outside once it is removed. Once the air passes through the felt diffusion later, the air will react with the activated carbon, rate-controlling binder, and electrolytes, which will result in a safer exothermic reaction compared with the older water heated version.
These newer versions are supposed to be safer to use out in the field and helps soldiers to conserve water out in the field. Both types of heaters will heat up to about 100 degrees Fahrenheit, so make sure to use caution when handling the package.
The newer version will also allow you to use this in a submarine, an aircraft, or any enclosed environment, which is probably one of the biggest advantages to the new
What Does An MRE Contain?
If this is the first time you are testing out the MRE, you may probably be wondering what’s inside the pouch. Though there isn’t an exact answer to this question, there are a few things that you will most commonly find inside an MRE pouch.
MREs are allotted to soldiers who are posted on the field operations. But for civilians, they can be a little different, but not much.
The main goal of the MRE is to provide all the nutrients that the body needs when out in the field. That is why the manufacturers try to add as many items as possible to fulfill all the nutritional requirements that a person needs.
A typical MRE contains the main course, a side dish that consists of rice, corn, or maybe fruit depending on your pack. It also contains crackers or bread for carbohydrates.
You will also find peanut butter, jelly, or even jam inside, which you can spread on the bread. Drink mixes such as lemon-lime and coffee are also included. Moreover, the desserts inside US MRE packs are always outstanding. You will find either cookie or pound cakes inside.
But again, there are several different varieties depending on the packaging date, whether it’s a civilian or military MRE, and the manufacturer.
Here’s what came in my MRE pack:
- Main Entrée: Chili Mac & Cheese
- Lemon Poppy Seed Pound Cake
- Crackers and Cheese Spread with Jalapenos
- Carbohydrate Electrolyte Beverage Power: Fruit Punch Flavor
- Beverage Base Powder: Lemon-Lime Flavor
- Skittles
- Packet of ground pepper
- Plastic spoon
- Hot Beverage bag
- Freeze-dried instant coffee pack
- Creamer pack for coffee
- Salt pack
- Sugar pack
- Moist Towelette
- Napkin
- Chewing gum
- Book of matches
As you can tell from the list above, manufacturers focus on giving you all of the nutrients you would need, including food items to maintain your sugar level.
Related Questions And Answers
Can You Reuse The MRE Heater?
MRE heaters contain chemicals that are for single use only. Since these heaters don’t use any flame or electrical current to reheat the food, they use chemical-based elements that release heat during the reaction. The addition of chemicals limits its usage to a single time only.
If you are using a water-activated MRE heater, then you cannot reuse it again. It will only be active for a short time. Once the reaction settles, the bag will be completely useless..
Apart from the water-activated heaters, the new air-activated heaters stick to the MRE’s pouch, making it entirely disposable.
How Long Do You Heat An MRE?
MRE is usually pre-cooked food, which makes them pretty much instant. Unlike traditional food, they are designed in such a way to take less time. Most MREs will take 5 to 15 minutes at max to thoroughly heat the food and make it ready to eat.
However, it depends on the situation you are in. If you are out somewhere in a colder place, then the food may take a bit longer to heat up.
Can You Eat An MRE Without Heating It?
MREs are designed for soldiers, which means they are already cooked. You don’t need to spend a lot of time cooking them. However, if you want to taste your MRE without heating it, you can eat it directly.
Most of the contents inside the MRE doesn’t need heating at all. For instance, you can eat dessert, crackers, and snacks straight from the package. The main course may not taste as good without heating it, but it is still eatable.
Are MRE Heaters Dangerous?
MRE heaters contain chemicals that trigger an exothermic reaction when coming in contact with water or air. Most of them aren’t considered toxic. Having that said, they produce hydrogen gas, which can be dangerous when using inside an aircraft, a tent, or anywhere near exposed flames.
Apart from that, the MRE heaters can ignite if you expose them to a flame or a spark. This can be dangerous especially when you are using it inside a camping tent.
What Chemicals are in MRE Heaters?
Most MRE heaters come with magnesium inside. However, there isn’t only magnesium that is doing all the heating job.
The element is alloyed with iron and some table salt that produces an exothermic reaction when comes to contact with water.
As a result, the heater starts heating and you can reheat your food by placing the MRE pouch inside.
What happens if you overfill an MRE heater?
The water-activated MRE heaters come with a limit marked on it. The reason for that limit is because the design of the flameless heater doesn’t require a lot of water to start the reaction.
The worst thing that can happen is the heater doesn’t work properly if you fill the water level too high.
Why isn’t my MRE heating up?
If your MRE isn’t heating up then there might be a few problems with your food pack. First of all the plastic pouch of the heater may be punctured.
In addition to this improperly closed heaters also don’t work as efficiently because the humidity in the air reacts with the heater.
Another common problem is usually the quality content of the MRE. If you are using an older MRE then it may have lost its quality which may not be as effective as the fresh one.
Sometimes the pouch of the MRE can be a problem. In this case, the best way to heat up your MRE is by transferring it to a pot and heating it in the microwave.
Final Thoughts
Microwaving MREs is an easy way to heat up your MRE entrée if you don’t want to go through all of the “trouble” as described above with the flameless heater.
So, “Can You Microwave MREs?” The answer to this question is definitely yes! But remember, are you going to have access to a microwave when SHTF? Probably not!
We would love to hear your comments and thoughts below if you have something to add.