Thermal Cooking
The concept of Thermal cooking is not a new one. It has been used in Europe and Asia for many
years. It was also used by many of our Parents or Grandparents as a matter of fact. They May
have called it a Hay Box. I think in general Thermal cooking falls into a few groups.
Hay Boxes
Hot Boxes
Modern Thermal cookers
Thermos cooking
Hot Water Misc. heat
A hay box, Hot box straw box or "fireless cooker" is a primitive cooker that utilizes the heat of the food being
cooked to complete the cooking process. Food items to be cooked are heated to boiling point, and then insulated.
Over a period of time, the food items cook by the heat captured in the insulated container. Generally, it takes three
times the normal cooking time to cook food in a hay box.
Hay box cooking can save vast amounts of fuel, but there is a risk of bacterial growth if the food items are allowed
to remain at a warm temperature for an extended period of time. For this reason, food cooked in hay boxes is
normally reheated to boiling before eating.
If you’re excited by the possibility of cutting back on your home energy consumption and saving a few precious
dollars on your energy bill, let me introduce you to the idea of hot box cooking.
A simple hot box provides a wise solution to preparing meals without the excessive use of your stovetop or oven.
You can make a hot box (also called a “hay box”) for free, with very simple and recycled materials that you
probably already have lying around your house, or with stuff that you can easily hunt down.. . And you can
fashion your own hot box with things that you can find around the house (even better, things that may have
otherwise ended up in the recycling or garbage bins).
The sort of hot boxes I am accustomed to, are simply cardboard boxes.
Cardboard is a great insulator – it keeps cold things cold and hot things hot.
You can also use coolers, or any material that is a good insulator.
The trick to making your hot box work is to create an extra few inches of
insulation on the inside, forming a protective layer all around your pot. For
this, you can use old towels or blankets, or even phone books and scrap paper.
Don’t be skimpy though – you need to pack it tight to get the most out of your
creation.
Next, it’s time to throw in your food, still in the pot it started cooking in, with
the lid firmly on. The beauty of a hot box is that if you partially cook your meal and stick it in the box, it will
slowly finish cooking over the next 6-8 hours. The most effective hot box delicacies are those that would do well
in a slow cooker: rice, various legumes, or even stews. You may want to stay away from cooking meat using this
method until you’ve worked out the kinks in your system, since bacteria from undercooked meat or poor
temperature control could make you sick.
How to make a hot box
To make a hot box, grab a large cardboard box (one that will be large enough to house several inches worth of
insulating material, and your favorite cooking pot) or other suitable container. Sometimes an Ice chest may work;
others have used a wooden box, or even a drawer. Look around and be creative. I have seen a few made to look
like a foot stool. Next, simply line it with your insulating material. If you’re using straw you might consider
getting a second, smaller box to put your pot in to keep things separate and tidy. Polyurethane foam is a good
insulator. It comes in sheets and in the beads or pellets however many other things work very well too. Even
phone books and news paper old magazines can be used. I like the idea of lining it with a layer of Mylar like one
gets from the Thermal blankets or left over Balloons or perhaps a heavy garbage sack might work. Just be sure to
keep a good layer of insulation between the pot and the plastic. Shredded paper also works well. Styrofoam is
nice and can be cut to the size of the pot you will be using if you have it available. The insulation should fit snug
around your pot. You will need enough room in the container to insulate on top on the pot as well.
Finally, put your pot in the fully insulated hot box, and make sure to cover it with some extra towels or insulating
material. (If you have some sleeping bags, you don’t even need a box: simply wrap your pot in the middle of a bag
or two.) Remember: the more insulation, the better! You want to keep that heat in!
Thermal Cookers
In case you're unfamiliar with thermal cookers, they are large, well-insulated vacuum pots into which you place a
heated pot of food. Due to heat retention, the food keeps cooking as though it is in a slow cooker, but with no
added heat after the initial heating up, and reviews mention that the food doesn't get so overdone as slow cookers.
Which thermal cooker tests the best at heat retention? From the reviews at Amazon it looks like the Zojirushi is
good, but the Thermos/Nissan one looks like it might be good as well (positive sealing lid, carrying handle, might
be less expensive.) There is also a brand called Dreampot that you can put 2 inner pot into at the same time.
Looks interesting but have not used this one.
Cooking is a Thermal cooker or Hot box is different from a Crock Regardless of what you may read. The heat is
brought up in the Pot and then it is put in the insulator and uses the heat contained there to finish the cooking
process gradually and slowly decreases. The heat in a crock pot gradually increases and stays constant. After
the pot in brought up to a boiling point and is ready to be set into the insulator there will be no burning or drying
out of the food.
To cook in the Thermal cooker recipes that are going to be stewed, simmered, steamed, or are saucy, work well.
With some things like rice you may actually need a little less water and you do not lose much to evaporation. I
like to cut the meat into chunks as they cook faster and are easier when serving from the pot.
Put your ingredients into the pot
Brown onions, Meat or etc if you like
Add liquid and bring to a boil
Boil about 5 min or most things but up to 20 may be needed for more dense things.
Then remove from heat and put into the insulator and leave.
Something will be done in just slightly longer than normal.
You can take it in the car set on the counter or take in on the 4 wheeler.
Recipes
There are too many to list even a part. Many of your favorites will work. There is also a web site that may be
helpful called The Thermal Cooker Thermal cooking web log.
Rice
1 cup rice white or brown
2 cups water
Touch of salt
Put into pot and bring to a boil. Cook 2 minutes on medium boil
Remove and put into liner and leave 30 min for white and longer for the brown.
Italian Soup
1or 2 cans tomatoes, or a qt.
1 chopped onion
Green pepper
Green beans canned or fresh about 1 can
Carrots 1-2 cups
Garlic
Salt and pepper
Basil, parsley, oregano, dried or fresh
Garbanzo beans, small white or kidney at least 1 can of whatever you have. If using dried you should soak these
the night before and may want to start them first for a while
Green chilies, corn, olives, or mushrooms depending on what you have on hand
Meat balls or beef about 2 cups
If meat is raw brown in a little oil and then add the other ingredients and bring to a boil and boil 5 min and remove
to the liner. Leave for 30 min to 2 hours depending on if you are using raw meat to start or not. Longer is all
right
Dream-Pot Fruit and nut loaf ©
June 23rd, 2000
Selected from the Winter 2000 Recipes.
Boiling time on stove: 15 minutes
Cooking time in the Dream-Pot: 45 minutes minimum
Ingredients
1 cup boiling water
½ cup golden syrup Maple or karo could be used.
1 Tbsp butter or margarine
1 tsp of soda
1 egg, beaten
2 cups S.R. flour If using regular flour add 1 tsp of baking powder
¼ to ½ cup sugar or sweetener could be used.
1 tsp mixed spice
1 cup mixed fruit
½ cup walnuts
Method:
Mix together the boiling water, golden syrup, butter or margarine, and bicarbonate of soda.
Cool, and then add the beaten egg.
Add the remaining ingredients.
Spray 3 x 415g fruit or soup tins well with a non-stick spray.
Divide the mixture evenly between the tins.
Cover each tin with double foil, pressed down over the sides of the tins.
Place the tins in the base of the large inner pot, and pour boiling water two-thirds up the sides of the tins.
Bring to the boil and gently boil with the lid on for 15 minutes. Check intermittently to maintain the boil.
Transfer into the Dream-Pot for 45 minutes minimum.
Remove and stand for 5 minutes before tipping out gently onto a cooling rack.
When cold, slice and spread with butter.
One of the most useful "cookers" we have in our kitchen is a Thermal Cooker. All you have to do is put all the
ingredients in the pot, take it to a boil, then leave it to cook some more for a few hours (no electricity required during
this phase). And the food from the pot is nicely warm when you're ready to eat.
What is a thermal cooker and how does it work?
A thermal cooker (also called a thermal cooking pot) works much like a crock pot. It is made up of two pots:
• Insulated outer pot
• Stainless Steel inner pot
The food is put to the boil on the stove in the inner pot before being placed in the outer pot. The heat (from the boiling
process) is retained inside the pot, allowing the food to continue cooking slowly.
The cooker is excellent for soups and stews, anything you would normally use a slow cooker or crock pot for.
The thermal cooker can also retain cold temperatures, and can thus function as an icebox or cooler.
Diagram from Thermos Shuttle Chef.
Advantages
• Saves gas and electricity as food cooks in its own heat.
• Fast and convenient, in most cases needing only 10-15 minutes to bring ingredients to a boil.
• As it doesn't use gas and electricity once the dish is sealed into the outer pot, you can safely leave the house as the
food is cooking.
• As this is a slow cooking method, it is possible to cook the protein (meat) till tender and still have the vegetables
retain their shape and texture.
• Excellent for picnics and hot meals on day trips as it keeps for up to 8 hours.
Estimated cooking times
• Generally 10-15 minutes to boil, with most foods ready to eat in 2-3 hours.
• For food with large chunks of meat, you may want to boil/simmer for up to 30 minutes in the inner pot, and leave the
food in the pot for 6-8 hours.
Basic cooking method:
• Put the ingredients into the inner pot, cover with the lid, and place directly on the stove.
• Bring to the boil, then simmer. This takes 10 to 30 minutes (the simmering time depends on the type of food you're
cooking).
• Then take the inner pot, and place it in the outer pot.
• Close the lid tightly.
• Leave the dish in the pot for a length of time (the minimum amount of time required to cook the dish depends on the
type of food you're cooking).
Points to watch out for when using the cooker
• The inner pot should be about 80% full. The more the contents inside the pot, the more it will retain heat (Any air
inside will rapidly reduce the temperature). Products are probably Zojirushi Thermal Cooking Pot, the Thermos
Shuttle Chef and the Tiger Thermal Magic Cooker.
Question: Can I buy cheaper alternatives to the well-known brands?
My family has actually used thermal cookers made by different manufacturers, and find that the cheaper products do
work for most dishes.
However, the more well-known (and more expensive) products definitely do provide better heat distribution and
retention.
The cheaper products may require you to cook on the stove for a longer time than what
I've indicated on this page, as the stainless steel used to make the inner pot may be of lower quality. I also would be
careful how long I leave the food in the pot, as heat loss may be more rapid.
Question: What are the types of thermal cookers available?
Size.
The most effective would be the larger ones (around 4 to 5 liters or more). A friend of ours who used a smaller thermal
cooker found that it doesn't cook that effectively, and is more useful for keeping food warm.
Two inner pots version.
Some brands do offer versions which include two pots, allowing you to cook two dishes at the same time Just note that
you have to use both pots. If you're cooking only one dish, then you need to boil water in the other pot, and put it in as
well, otherwise there won't be enough retained heat to cook the food.
I've also seen versions with a full-size inner pot, and an additional smaller inner pot that slots onto the top of big pot.
Obviously, with these types, you have the option of( I) using the big inner pot with the small inner pot to cook two
dishes; or (2) you use the large pot by itself.
More Resources
• Thermos Shuttle Chef
Site for the Thermos Shuttle Chef. Lots of information and recipes.
• Thermal Cooking Weblog
Lots of recipes for the them
• Do not open the pot before the full cooking time for your dish has been reached, as doing so causes rapid loss of heat.
• Do not leave the food in the pot longer than the amount of time specified in the manufacturer's guidelines (usually up
to 6-8 hours). If you leave the food longer than that, the temperature may have dropped to a level where bacteria can
start to grow.
• If the food takes approximately 6-8 hours to cook, and you plan to eat it a few hours after that, you can re-boil the
inner pot and its contents before the 8 hours is up and then put it back into the outer pot.
CHOOSING A THERMAL COOKER
There are many brands of thermal cookers in the market, though the most well-known