Guide to Designing Retained Heat Cookers

The guides information is best viewed from this PDF file:

The Hot Box

Frequently Asked Questions

How does the HOTBOX work?

The HOTBOX uses the principle of insulated cooking. If you can keep the heat that is used to cook food, no replacement heat is necessary to complete the cooking process.

What type of dishes can you make in the HOTBOX?

Absolutely any food or dish that you would simmer in its liquid once you have brought it to the boil. All beans, legumes, grains and pulses; all soups, stews and casseroles; custard and yoghurt; steamed veggies; basmati, white, brown and sushi rice; mieliepap, samp and even pasta.

What are all the different uses for the HOTBOX?

The HOTBOX has a wide variety of uses. It is used to cook foods, to transport and continue cooking your food, as a warming oven and also used next to the braai keeping meat and all braai foods piping hot, as a plate-warmer keeping plates perfectly hot in the dining room, the garden or on the beach, it is a cooler box which is ideal for keeping drinks ice cold and storing ice, an incubation chamber for the making of foods like yoghurt and breads, a foot cushion or ideal camera rest when doing wildlife photography from your vehicle. (Really!)

Do I need to heat the HOTBOX?

Keep the HOTBOX away from open flame or fire. The heat required to cook the food is generated conventionally with electricity, gas, fire or paraffin. The HOTBOX is never heated in any way.

How long do foods cook for in the HOTBOX?

The cooking time for different foods varies from 20min (whole rolled oats) to 12 hours (oxtail). Foods mostly cook for more or less the same length of time or just slightly longer.

What environmental impact would the regular use of the HOTBOX make?

If you used the HOTBOX only 5 times per week your household would save 119kg of CO2 per year. If 500 000 households did that it amounts to more than 60 000 tons of CO2 per year. At least 70-80% of cooking time is saved and therefore the use of valuable resources such as electricity, gas, wood, paraffin, money and time is drastically reduced.

Does it really cook my food?

Yes! It really cooks your food. To truly benefit from the HOTBOX a subtle shift in thinking is required but once you see the incredible benefits you could never look back. It cooks your food and keeps it piping hot. The more you incorporate it into your daily life, the more you will find you use it.

What if my food isn’t cooked?

A degree of experimentation is necessary to get exact cooking times for different meals. It is important to use pots with tight-fitting lids and check that you’re not opening the lid unnecessarily. Hard and dense foods that have to be soaked such as chickpeas may need to be re-boiled and placed back into the HOTBOX for the last few hours. Alternatively just boil food on the stove for a little longer before transferring to ensure that all the food is at boiling temperature and not just the water.

How long does food stay hot for?

Food stays hot for up to 8 hours and remains warm for a few more hours. After 8 hours, unopened, the temperature of the food in the HOTBOX is approximately 56 degrees Celsius.

What do I use it for when I’m braaing or on holiday?

Keep braai meat and veggies hot as it comes off the fire. Cook and keep meals hot whilst traveling or hiking. Ideal when traveling in confined spaces such as caravans or yachts because you can reduce the amount of cooking gas needed by up to 50% which frees up your space.

Is there any safety measures involved in the use of a HOTBOX?

The HOTBOX must never be heated or held close to open flame or fire due to the flammable nature of the polystyrene balls. For health reasons don’t put a partially-eaten pot of lukewarm food back into the HOTBOX without first heating it, since HOTBOXES are not only excellent cookers but also ideal incubation chambers for yoghurt and other bacteria-rich food.

Why is it a healthier way of cooking?

Once the food has been transferred to the HOTBOX, the heat drops quite rapidly from boiling point to approximately 88 deg Celsius. This heat is then maintained and very gradually drops by an average of 4-5 deg per hour. It is a known fact that high heat destroys the live enzymes in your food and therefore cooking at a lower temperature preserves nutrients. HOTBOX cooking can never over boil or burn your food and food definitely retains more juiciness and flavor.

What type of pot do I use in the HOTBOX?

The pots that you usually use at home. A nice tip is to line the bottom HOTBOX cushion with an old dish cloth to protect the base of the HOTBOX from dirty or stained pots.

How do I wash the HOTBOX?

Hand wash or machine wash on a gentle/delicate spin cycle with cold water. Wash at max 30deg Celsius. Dry thoroughly in the sun – shake during drying to move polystyrene balls and to dry equally.

Do not dry clean or iron. Machine washing is the sole responsibility of the consumer. Fabric has not been pre-washed.


Brown and White Rice:

  1. Put 1 cup of rice and 2 cups of cold water in a pot.
  2. Add salt to taste.
  3. Place lid on pot and bring to the boil.
  4. Simmer for 1 minute.
  5. Remove from the heat and place in the HOTBOX for 30 minutes (white rice) or 45-60 minutes (brown rice), or until all the liquid is absorbed.
  6. Rice remains perfect in the HOTBOX for hours as it does not dry out or overcook

Lamb or Beef Stew:

  1. Fry onions, garlic and spices in oil.
  2. Fry your cubes or knuckles of meat until brown.
  3. Add selection of chopped vegetables, tinned tomato and stock.
  4. Ensure that the food is covered by the liquid.
  5. Bring food to the boil and cook for 15-20 minutes.
  6. Transfer to the HOTBOX – bigger and tougher pieces of meat require up to 12 hours of cooking in the HOTBOX.
  7. Return to stove and thicken your stew with Bisto or cornflour just before serving (optional)
  8. Serve directly from the HOTBOX with rice or pasta and a green salad.

Creamy Chicken & Corn Soup (a little time consuming but delicious)

  1. Place a whole chicken in a pot and fill with water, barely covering the chicken.
  2. Add celery sticks, whole garlic cloves, stock powder, bay leaves, salt and pepper to the water.
  3. Bring to the boil for a few minutes and transfer to the HOTBOX for approximately 2 hrs.
  4. In a separate pot melt approx 100-150 grams of butter until it sizzles.(the more butter you use the richer your soup will be)
  5. Add a variety of chopped veggies (such as cabbage, carrots, broccoli, leeks, onion, beans and courgettes) to the butter.
  6. Stir it with a wooden spoon to coat the veggies in the butter.
  7. Turn the heat down as low as possible and place the lid on tightly.  “Sweat” the veggies in the pot until soft, stirring every once in a while.  The sweating process takes about 30-40 minutes.
  8. Once the chicken is cooked drain off the water/stock into a jug or suitable container (You will use this lovely chicken stock to make your white sauce)
  9. Make a regular béchamel/white sauce with a small amount of milk and use the chicken stock for the rest of the sauce.
  10. Debone your chicken – the meat will be very soft and tender – and cut chicken into small bits.
  11. Add the chicken, “sweated” veggies and fresh or frozen corn to the white sauce.
  12. Add a dollop of cream or Greek yoghurt to the soup and season according to your taste.
  13. Garnish with ground black pepper and a small bunch of fresh coriander.

Traditional South African Mielie pap:

  1. Bring 2 ½ cups of water to the boil
  2. Stir 1 ½ cups of mielie meel and a pinch of salt into the boiling water.
  3. Stir thoroughly whilst boiling until all the water has been absorbed.
  4. Transfer to the HOTBOX and leave for approximately 30 minutes.
  5. Serve directly from the hotbox.

Samp and Beans

  1. Place I cup of samp & beans in a bowl, cover with water and soak overnight.  Rinse and drain.
  2. Bring samp & beans to the boil in 3 cups of salted water and simmer for approximately 20 minutes on the stove.
  3. Bring it back to a rapid boil and then transfer to the HOTBOX for approximately 4-5 hours or until soft and all the water is absorbed.
  4. Add butter, freshly ground black pepper, seasoned salt and crumbled feta cheese and enjoy as a light meal or accompaniment to a meal.

Thermos RPC-6000 6L Thermal Cooker

Thermos Thermal Cooker RPC-6000W 2x3L Thermo Pot

RPC-6000 thermal cooker with two 3L inner pots

Thermos also offers the RPC-6000 in a two 3L inner pot configuration which adds to the versitility of this thermal cooker. You are able to cook two recipes at the same time for example, rice and beans, rice and curry etc. or fill them both up with the same recipe for double the amount.  I’ve also used it with just a single 3L pot to cook smaller portions and filled up the empty space inside the outer pot with a small blanket, towell or rag to help retain the heat better.

Chicken Carbonara –

Chicken Carbonara

There is no need to precook the pasta in this dish.

Meat Balls
400 grams of chicken mince
2 cloves of garlic 1 egg
1 tablespoon of finely chopped parsely
1 tablespoon of flour
A pinch of salt and pepper
2 tablespoons of oil
2 onions coarsely chopped
1 stick of celery sliced
2 zucchini’s sliced
1 x 500 ml jar of carbonara sauce
500 ml of chicken stock
1/2 a cup of fresh parsely chopped
Salt and pepper to taste
1 1/2 cups of spiral pasta
Grated cheese to serve.

Simmering time on the stove top: 4 minutes

Thermal Cooking time: 1 hour minimum

1. Mix together the chicken mince, garlic, egg, finely chopped parsely, flour, salt and pepper.
2. Seperate into small portions.
3. Roll these portions into balls approximately 2 cm in diameter.
4. Heat 1 tablespoon of oil in the inner saucepan over a low-medium heat.
5. Brown half the meat balls and place them to one side.
6. Brown the other half of the meat balls and place them with the rest.
7. Add the other tablespoon of oil to the saucepan and brown the onions over a low heat for 2-3 minutes.
8. Add the garlic and celery and continue to cook for a few minutes until the onions start to clear and soften.
9. Add the zucchini and stir fry for a further minute.
10. Add the meat balls back into the saucepan and stir in the Parsely.
11. Add the carbonara sauce and the stock.
12. Bring the mixture to the boil.
13. Turn down the heat and simmer gently for 3 minutes.
14. Add the pasta to the simmering sauce and continue to simmer a further minute with the lid on.
15. Turn off the heat and transfer the saucepan into the vacuum insulated outer container.
16. Close the lid and leave for a minimum of 1 hour.
17. Serve with grated cheese and a tossed green salad of your choice.

Thai Green Curry Chicken –

Thai Green Curry Chicken

A delightful mild curry chicken that has so much flavour.

1 tablespoon of Oil
500 grams of sliced Chicken Fillets
3 tablespoons of Green Curry Paste (Valcom Brand is wonderful) NOTE: You can increase or decrease the amount of curry paste to suit your own requirements.
400 ml tin of Coconut Cream
2 tablespoons of Fish Sauce
2 teaspoons of Sugar
1 cup of chopped Pumpkin
1 cup of Green Beans (you can use dried or frozen also)
1 cup of fresh Basil Leaves, chopped
2 Kaffir Lime Leaves or 1 cup of freshly chopped Coriander
Fragrant Rice to serve.
NOTE: The supermarkets have excellent Basil and Coriander pastes that can be substituted if required.

Simmering time on the stove top: 5 minumtes

Thermal cooking time: 30 minutes minimum

1. Stir fry the curry paste in the oil over a low heat, until fragrant.
2. Add the chicken and pumpkin then stir fry over a medium heat for a few minutes.
3. Add the remaining ingredients, lower the heat and slowly bring it to the boil.
4. Put the lid on and simmer gently for 5 minutes.
5. Turn off the heat and transfer the pot into the outer insulated container and close the lid.
6. Leave for a minimum of 30 minutes.
7. Serve on a bed of fragrant steamed rice.
NOTE: If you are using the double pot Thermal Cooker you can be cooking the rice at the same time in the second pot.

Corn and Pork Ribs Soup –

Corn and Pork Ribs Soup (from the “The Adventure of Ms J & Mr P”

We grew up drinking lots of soup made by mummy. Asian mum loves to make soups. Soups are nutritious and they really warms your heart. Hope this Corn and Pork Rib Soup will warm yours too!

Preparation Time: 8 mins
Cooking Time: 10 mins
Waiting Time: 2-3 hours

1 Carrot
1 Tomato
2 Sweet Corns
1 small bit of young ginger
1/2 kg Pork Ribs

1. Cut the tomato into wedges. (4 or 6 wedges, up to you)
2. Break the corns into 3 pieces.
3. Cut the carrots into little chunks.
4. Clean the ginger by getting rid of the skin and cut them in big pieces.

5. Prepare the pork by boiling a pot of water and boil the pork for 5 mins then drain.

6. Pour all the ingredients into the pot with 1.5 litres of water.

7. If you are like us, we like using Thermal Pots. This is an OEM brand which is cheaper. You can get Tiger or Le Gourmet brands which cost 3 or 4 times more, and yet work the same.

We boil the above for 5 mins and then turn it off and transfer the pot into the Thermal Pot. Wait for 2 or 3 hours.

8. When we are ready to serve, we take out the pot, boil it again for a few minutes and then serve. Add salt to your taste.

We usually prepare the soups on Saturday mornings around 9 AM. We will drink the soup at noon. We like using Thermal pots because we do not need to care about the fire.

If you realise, we use an induction cooker too! Induction cooker converts 80-90% of energy to heat, compare to other types of cooking methods (eg gas flame, hot plates) that usually only use 45% of the energy and the rest wasted.

For those interested:
Carrot: Daucus carota subsp. sativus
Domestic Pig: Sus scrofa domestica
Ginger: Zingiber officinale
Sweet Corn: Zea mays var. rugosa
Tomato: Solanum lycopersicum

These recipes are written for standard cooking on a stovetop or in an oven. To adapt them for a thermal cooker, use the same ingredients and follow the same steps, using the inner thermal pot.

Bring ingredients to a boil, making sure the internal temperature of the meat reaches 203 degrees (this may require 10 minutes of boiling). Place the inner pot into the insulated outer thermal pot; seal and let sit for the same amount of time as called for in the original recipe.

Sweet-Sour Spareribs
5 pounds spareribs
2 tablespoons soy sauce
1/4 cup flour
1/4 cup vegetable oil
2 cloves garlic, crushed
2 small pieces ginger, crushed
2/3 cup apple cider vinegar
1-1/2 cups water
1 cup brown sugar
2 teaspoons salt

Cut spareribs into 1-1/2-inch pieces. Sprinkle with soy sauce and flour; mix gently.

In large saucepan, heat oil. Brown spareribs with garlic and ginger; drain fat.

Add remaining ingredients and simmer 55 minutes to 1 hour. Serves 6.

Approximate nutritional analysis, per serving: 900 calories, 62 g total fat, 21 g saturated fat, 185 mg cholesterol, 1,300 mg sodium, 41 g carbohydrate, no fiber, 35 g sugar, 41 g protein

Chinese-StyleOxtail Soup
2 pounds oxtail pieces
2 quarts water
2 large carrots, in 2-inch pieces
1 cup shelled raw peanuts
5 dried red dates
2 teaspoons salt

Put oxtail pieces into large sauce pot; add water to cover. Boil 5 minutes; drain and rinse oxtail pieces.

Add 2 quarts water and remaining ingredients. Cover and bring to boil; simmer 2-1/2 to 3 hours. Serves 6.

Approximate nutritional analysis, per serving: 250 calories, 17 g total fat, 4 g saturated fat, 40 mg cholesterol, 800 mg sodium, 8 g carbohydrate, 3 g fiber, 3 g sugar, 18 g protein.

Baked Beans with Portuguese Sausage
1 pound Portuguese sausage
1 can (1 pound, 15 ounces) pork and beans
1 can (15 ounces) kidney beans, drained
1 large onion, chopped
1 cup ketchup
2 tablespoons Worcestershire sauce
1/3 cup brown sugar
3 tablespoons dark molasses
1 tablespoon mustard
1/2 teaspoon vinegar

Preheat oven to 350 degrees.

Cook sausage in water 10 minutes; drain and slice.

Put sausage, beans and onion into 3-quart baking dish. Combine remaining ingredients and stir into bean mixture. Bake, uncovered, 1 hour. Serves 10.

Approximate nutritional analysis, per serving: 350 calories, 14 g total fat, 4.5 g saturated fat, 25 mg cholesterol, 1,250 mg sodium, 45 g carbohydrate, 7 g fiber, 23 g sugar, 16 g protein

Hawaiian Electric Co. presents this weekly collection of recipes as a public service. Many are drawn from HECO’s database of recipes, accessible online at

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