Kitchen Must-Have: The Thermal Cooker

Updated on March 5, 2020
Marlene_OnTheWall profile image

I love educating others about the necessary appliances they need in their kitchen.

One of the most useful cookers we have in our kitchen is the thermal cooker. All you have to do is put all the ingredients in the pot, bring it to a boil, then leave it to cook some more for a few hours (no electricity required during this phase). The food from the pot is nicely warm when you are ready to eat.

What is a thermal cooker, how does it work, and how do you choose one?

What Is a Thermal Cooker, and How Does It Work?

What is it? A thermal cooker (also called a "thermal cooking pot" or "vacuum pot") gives results like a crockpot or slow cooker.

It's made up of two pots:

  • Insulated outer pot
  • Stainless steel inner pot

How does it work? The food is placed in the inner pot, then brought to a boil on the stove 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 crockpot for.

The thermal cooker can also retain cold temperatures, and can thus function as an ice box or wine cooler.

Diagram from Thermos Shuttle Chef.
Diagram from Thermos Shuttle Chef.


  • Saves gas and electricity as the food cooks in its own heat.
  • Fast and convenient, in most cases needing only 10-15 minutes to bring the ingredients to a boil. Once you have placed the inner pot into the outer pot, you no longer have to watch the food.
  • As it does not use gas and electricity, once the dish is sealed into the outer pot, you can safely leave the house while 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 you do not need access to electricity or gas (after you bring the food to the boil and place it in the outer pot), and the food 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 need 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

  1. Put the ingredients into the inner pot, cover with the lid, and place directly on the stove.
  2. Bring to the boil, then simmer. This takes 10 to 30 minutes (the simmering time depends on the type of food you are cooking).
  3. Then take the inner pot and place it in the outer pot.
  4. Close the lid tightly.
  5. 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 are cooking).

Points to Watch out for When Using the Cooker

  • The inner pot should be about 80% full. The more contents in the pot, the more it will retain heat (any air inside will rapidly reduce the temperature).
  • 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 reboil 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 on the market, though the most well-known products are probably the 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 found that the cheaper products do work for most dishes.

However, the more well-known (and more expensive) products definitely provide better heat distribution and retention.

The cheaper products may require you to cook on the stove for a longer time than what I have 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 litres or more). A friend of ours who used a smaller thermal cooker found that it does not cook that effectively, and is more useful for keeping food warm.
  • Two inner-pots version: Some brands 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 are cooking only one dish, then you need to boil water in the other pot, and put it in as well, otherwise there will not be enough retained heat to cook the food.
  • Full-sized inner pot: I have also seen versions with a full-sized 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 using the big inner pot with the small inner pot to cook two dishes or using the large pot by itself.


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    • profile image

      Sylvia He 

      2 years ago

      HI, I am wondering how many of you have cooked beans (alone) in a thermos cooker. what are the results? I was wondering because cooking beans the regular way in a large pot smells up my kitchen, uses a LOT of water and electricity and the results with chick peas are not that good.

      Beans I like to use: Pinto, black, chili, baby lima and chick peas. one type at a time. your review/experience with this method (thermos cooker) will be invaluable!!

    • profile image


      4 years ago

      Informative article, thanks for posting! I love thermal cooking! I find it interesting how forgiving thermal cooking can be. I studied retained heat cooking for several years and have published the book Let's Make Sense of Thermal Cooking. It can be found at

    • profile image


      7 years ago

      We helpful to acquire at the top of lifestyle although recently I've truly built up the resistance.

    • profile image

      May Lee 

      8 years ago

      Cooking for one what size would you suggest with Thomas thermal cooker. Thanks.

    • profile image

      Allan Rush 

      9 years ago

      There is a growing list of excellent accessories now available for the Thermos Shuttle Chef Thermal Cooker and these can be utilized in many of the other brands as well...they can be found on and as well as many delicious recipes tips and hints

    • profile image

      Ron Carter 

      10 years ago

      A great Post considering the topic can be very mundaine, I will try it this summer while grilling. Green Beans :)


      Warmest Regards



    • profile image

      Rosie Peters 

      10 years ago

      The thermal cooker looks a lot like the big Asian rice cookers that do such a superior job to the more basic western style. This is a really interesting product.

    • profile image


      10 years ago

      my helper accidentally place the outer thermal pot on fire for about 5 minues will it damage the pot?

    • profile image


      10 years ago

      anyone know who made these pot such as "Thermos Thermal Cooker RPC4500 4.5L Thermo Pot" which country?


    • profile image

      Allan Rush 

      10 years ago

      Have a look at for a growing community of thermalcooks and lots of recipes

    • profile image

      Thermal Cooker 

      10 years ago

      I'm not sure if this site ships thermal cookers to South Africa: but you can try them. There are some sites listed on this blog from various places around the world that sell thermal cooker too:

    • profile image


      10 years ago

      Where in South-Africa can I buy a thermal cooker.

      I got one as a wedding gift about 16 years ago and it is wonderful to use. I would like to buy one for my daughter.

      Please can somebody help me with information.

    • profile image

      Sue Reynolds 

      11 years ago from

      Am glad to see others are excited about thermal cooking pots.  I cooked with crock pots for many years, but you can't beat a thermal cooking pot for the ultimate in prep and forget (at least until supper time.)

      Sue -

    • Marlene_OnTheWall profile imageAUTHOR


      11 years ago from Singapore

      Thanks for your comment, Hendrika. I never thought about that -- that a thermal cooker may be useful in countries where electricity supply is erratic. I've read, though, that many campers and picnickers find the product extremely useful -- I guess for much the same reason, easy cooking without necessarily having to have access to electricity.

    • Hendrika profile image


      11 years ago from Pretoria, South Africa

      I need one of these. In South Africa, power is not a given, so if I have power to start the meal it can cook on its own. Better than the crockpot I'm using now!

    • Marlene_OnTheWall profile imageAUTHOR


      12 years ago from Singapore

      The How To Hub: Interesting. Here in Singapore, I'd understand 'Slow Cooker' to refer to crock pots! Great that you enjoyed my hub.

    • The How To Hub profile image

      The How To Hub 

      12 years ago from Australia

      What a well written hub on what could easily be a boring topic to some. My mother in law swears by her thermal cooker - we call them slow cookers in Australia, but that's probably just our infamous slang?...not sure : ) Interesting point about it being handy as an icebox also! I will have to remember that one, thanks.

    • Marlene_OnTheWall profile imageAUTHOR


      12 years ago from Singapore

      I think not many people know about the thermal cooker... yet! So no need to feel like a 'mushroom' lol. Thanks for commenting, and for letting me know that my hub did some good to somebody.

    • gss profile image


      12 years ago from Florida

      I will have to try a thermal cooker, did not they existed. I feel like a mushroom sometimes... always in the dark. I just recently discovered a rice cooker and use it all the time. Love it. Thanks.

    • Marlene_OnTheWall profile imageAUTHOR


      12 years ago from Singapore

      Hi Lilymag, The thermal cooker is very common in Asia, but perhaps not as well known in America or Europe.It's a great item to have!

    • Lilymag profile image


      12 years ago from Upstate New York

      I never knew there was such a thing! Thank you for educating me, this is such a great idea, can't wait to try it!


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