wrap the slow cooker?

ClareBroommaker's picture

Is there any safety reason not to insulate a slow cooker with a couple towels? It vents very little water, so I don't think the towels would get wet. The only possible problem I could think of is water somehow getting into the switch which is 1/3 the way up from the bottom the outer pot. It will be cooking at 180*F.

Ken's picture

What about trying it in an ice chest? Then no 'soft' insulation up against the slow cooker. Any moisture escaping the lid will escape the ice chest lid as well (because it's cracked to let the cord to the cooker in). Now that I write that, I may have to try it myself! I usually cook my first-of-the-month batch of pinto beans on the porch because my wife doesn't like the smell of them cooking and I do feel guilty about the wasted heat. Let us know what your results are and I'll do the same!

ClareBroommaker's picture

Well, just two and a half hours later I have results to share. I started smelling a "green" element to the chick peas, so slipped my hand under the towels and found the outer case of the crock pot was hotter than normal at the low setting. So I pulled the towels off and found it was boiling . I hope I haven't damaged the thermostat. :-(

ClareBroommaker's picture

Hmm, maybe there is no thermostat. I'll try to look this up.

Instead of slow cooking, have you considered thermal (retained heat) cooking? This is a relatively new hobby of mine, started in the last couple years. There is a really good primer on the topic in the website that Ken posted on the "Low Tech" thread: https://www.lowimpact.org/categories/retained-heat

Ken--beans cook GREAT using thermal cooking method! Ideal for it, and results are even better than the slow cooker, IMHO.
Rose Red has a couple good videos on the topic

I still haven't figured out. how to make good rice using this method (it ends up mushy on the bottom and crunchy on the top), but is good for making bread, and anything that I can make in a solar cooker or slow cooker!

Let us know if your slowcooker survived....I found this website that claims slow cookers apply a steady electrical current, and do not have thermostats....https://www.cookingmanager.com/slow-cookers-energy-efficient/
It also claims they use far more energy than we think, because of this feature, and has a discussion of the energy use comparison with an electric oven....anyone have a Kill-A-Watt who can take and share the data with us? I have a Kill-A-Watt, but don't use a slow cooker anymore....

ClareBroommaker's picture

I knew these beans are old and hard. I soaked them for three days, then decided to try the very long slow cooking. They've already cooked for three overnights! My slow cooker is okay, and I found that same info that they put out continuous heat, with no thermostat.

It just happens that at my room temp, the continuous heat they reached was 180* without any added insulation. I guess in my summer kitchen it would reach a higher heat. With insulation, we saw boiling, so effectively just the same as turning the switch to high. Low and high are the only choices. But I wanted to cook without boiling.

I think I might just turn these chick peas into the garden or compost pile and let them feed the soil, rather than myself.

mountainmoma's picture

Yeah, I wouldnt cook them to eat either ! If they sprout, you can plant them. So same as sprouting mung beans, but as soon as you see they are about to make that root tail, put them out in the garen to grow more beans. Take some and grind to make garbanzo bean flour. Sprout like mung beans for longer and then feed to your chickens. If all else fails, just compost them

I have a slow cooker labeled at 240W, and my meter said 255W when I turned it on for a moment. Oddly enough, "low" and "high" drew the same power. Maybe that means this model does have a thermostat? We don't use it often enough for me to remember if it cycles on and off.

For what it's worth, I think our toaster oven is labeled at 1400W. (Right now it's in a spot where it's inconvenient to check the label or plug into the meter.) I use the toaster oven a lot, and I'd guess it tends to be in "heat" mode about half the time, so even if it's using nothing the rest of the time it still uses energy faster than the slow cooker. If it's going to take three times as long in a slow cooker, then based on this they're probably about comparable in terms of total usage.

Ken's picture

Watts are the amount of energy being released, the Work you might say. Amps are comparable to the flow rate of the water in a garden hose, Voltage in this analogy, is the water pressure. Amps are what heats up wires and wastes energy as heat before it can get to the point you want Work to be done. This is why bigger wires and higher voltage has less line loss. An electric cookstove on a 120V circuit that needs 1500 watts at the burner will have twice the amperage of the same 1500 watts on a 240V circuit. Higher voltage has an efficiency advantage but the amount of calories it takes to cook a pot of beans is the same no matter what combination of time and watts you use.

Ken, I only boil my beans for 5-10 minutes, put them into a thermos and wrap in a down comforter. They're creamy smooth inside, absolutely perfect. And I guarantee that takes less calories to cook than any combo you can imagine that pumps energy in continuously for hours--regardless of the way the energy is applied. So this is NOT true "the amount of calories it takes to cook a pot of beans is the same no matter what combination of time and watts you use."....Just sayin'

Ken's picture

spiritchi - Unless your thermos keeps the beans above 140F the entire time, you are playing Russian Roulette with your beans.
Slow cooking is great and you do save energy but it's not worth risking your health and the health of anyone you serve those beans to...

And it is simply physics that a given pot of beans will require a given number of calories (heat units) in order to be perceived as "cooked". Whether you use a lot of heat wastefully for a short time or a little heat carefully for a long time, it's the amount that the beans actually experience that matters and that amount does not vary.

mountainmoma's picture

Because it is the amount of heat calories the beans absorb that counts, not just what we apply. So bringing to a boil and setting aside where it is insulated and does not lose the heat absolutely saves energy because of the extreme lessening of wasted heat.

Safety. If the beans and water have been brought to a boil for a few minutes, all the potential pathogens on the beans, water and inside of the pot have been killed. It doesn't matter that the temperature falls as long as the lid is not lifted to let in new potential pathogens. I have heard you can do the same with meat based soups. Our ancestors survived leaving food out, adding more to the pot, and bringin to the boil once or twice a day

ClareBroommaker's picture

My slow cooker (Rival Crock Pot) is truly old, made before some government agency enforced that slow cookers have to cook at a higher temperature for food safety's sake. It uses 75 or 150 watts, depending on whether it is turned to low or high. It also has the original design in which the crock is not removable. We've had a newer one, but did not care for it because it cooked too fast and hot.

David Trammel's picture

I think you are on to something with insulating the slow cooker, but you need to consider putting a timer on the cord. Insulate the thing like a haybox, set the timer to 30 minutes to bring it to a boil, then let it sit. Check the temp periodically and pop the timer on when the internal temp drops below a certain temperature. Saves you from having to bring it out and putting it back on the stove.

Ken's picture

A common perception is that when Homo erectus learned to use fire that it was primarily to roast meat and chase off hungry sabertooth tigers but I think it gets overlooked that MANY plants have varying amounts of toxins in them (evolved to discourage animals from eating them) and some of those toxins can be destroyed or diminished by heating. A good example is potatoes, another is beans -


From an evolutionary point of view, being able to cook enabled our early human ancestors to utilize the food resources in their area more efficiently than simply eating everything raw.

lathechuck's picture

The amount of energy delivered to the food may be constant, but there can be big variations in the amount of energy that escapes around the food. My microwave oven just heats the food, then some of the heat escapes to the air, then some of that heat warms the oven. My electric resistance oven heats the element, which heats the air, and some of that heats the food. A lot of it, though, heats the inside of the box and the door, while the food is cooking. I believe that the microwave is more efficient, at least for small batches.

Similarly, a gas burner lets lots of heat flow up around the pot (some that heat being the latent heat in the water vapor), but an induction element just heats the bottom of the pot, so it's more efficient.

A pressure-cooker spends less time being hot, so it loses less heat to the air around it, even though its temperature is higher while it's cooking.

One other thought, which came as I was watching my pasta cook a couple of hours ago: the water vapor that boils out of the pot, whether it's pasta water, bean water, or soup, is lost energy. I try to keep the water just hot enough to bubble, but not a "rolling boil", whether cooking or canning.

mountainmoma's picture

In the winter, none of that heat is lost, you are heating the home anyways. In summer, use your solar cooker outside. My daughter says on days she bakes, she doesnt have to turn the heater on. If you dont need that much heat in teh house, so the shoulder seasons, put the pot in a haybox, an insulated area, so it just cooks on tis own. People have wasteful habits when cooking. I find that I just bring the put to a boil for oatmeal, and turn it off. I dont bother insulating it, but I could. I could turn a larger pot or metal bowl upside done over it and then folded towel. For scotch oats, cut oat groats, I bring to a boil in the evening, and leave the pot out overnight. Bring to a boil in the morning, turn off. Great oats.

If you want to save more energy, turn off the hot water heater. Most things you clean do not need hot water, or you could do dishes with that water from cooking pasta. You do not need hot water to be clean, and they say the cold water washing is good for you.

mountainmoma's picture

This chart is total energy use, and most Californians heat house and hot water and cook with natural gas or liquid propane. Anyways, Space heating, Water heating, Air conditioning, Lights, Electronics. -- Then Cooking. I also like to cook efficiently, but your hot water heater is a much, much bigger user of energy.

I got rid of 3 window air conditioners when I bought this house. And, yes, it gets hot here. Yes, there are some days I can be sweaty in the house not doing anything. But mostly my other efforts to keep the indoor temperature from getting too hot work for most days ( planted vines, curtains closed in day, windows open at night) my youngest keeps the air conditioner off in Davis CA, that is central valley and hot, in her rented apartment. But if you have to have it, turn the thermostat up ! Turn it up to 80 or 85'F in summer and down to 65'F in winter, that will save more energy than the cooking. Look to cold washing of yourself, Wim Hof and a certain arch Druid recommend the benefits of washing yourself with cold water.

add photo: