Slow cooker - not as energy efficient as I thought

macman

tim_p said:

macman said:

<snip>
As to consumption, it take a fixed x kWH of energy to cook a meal, and x remains the same value, whether it's delivered at a rate of 200W over 14 hours, or 2,800W over an hour in a conventional oven.

Not quite. The slow cooker without a thermostat will take 2800 watts over 14 hours, whereas a conventional oven will switch on and off with the stat and probably use a lot less in the hour it’s on. Ours is rated at 2.2kW and uses nothing like that during an hours cooking. Sorry, just being pedantic. 

You are missing the point. Regardless of the thermostat kicking in and out, the energy input required to cook the meal is the same, regardless of the device you use. If it takes 2.8kWh to cook the meal adequately, and your conventional oven only delivers 2.2kWh or less in an hour, then you will either have to cook it for longer, or eat your beef casserole on the rare side. Your choice.

Billy_B_North

macman said:

tim_p said:

macman said:

<snip>
As to consumption, it take a fixed x kWH of energy to cook a meal, and x remains the same value, whether it's delivered at a rate of 200W over 14 hours, or 2,800W over an hour in a conventional oven.

Not quite. The slow cooker without a thermostat will take 2800 watts over 14 hours, whereas a conventional oven will switch on and off with the stat and probably use a lot less in the hour it’s on. Ours is rated at 2.2kW and uses nothing like that during an hours cooking. Sorry, just being pedantic. 

You are missing the point. Regardless of the thermostat kicking in and out, the energy input required to cook the meal is the same, regardless of the device you use. If it takes 2.8kWh to cook the meal adequately, and your conventional oven only delivers 2.2kWh or less in an hour, then you will either have to cook it for longer, or eat your beef casserole on the rare side. Your choice.

Where do you get the idea from that the energy to cook a meal is constant?

If you warm a steak up to 55 degrees throughout then that steak is cooked to medium. If you hold it at that temperature for ten hours it doesn’t progress beyond medium but you do throw a huge amount of heat energy into the room which of course consumes more energy.

lohr500

macman said:

tim_p said:

macman said:

<snip>
As to consumption, it take a fixed x kWH of energy to cook a meal, and x remains the same value, whether it's delivered at a rate of 200W over 14 hours, or 2,800W over an hour in a conventional oven.

Not quite. The slow cooker without a thermostat will take 2800 watts over 14 hours, whereas a conventional oven will switch on and off with the stat and probably use a lot less in the hour it’s on. Ours is rated at 2.2kW and uses nothing like that during an hours cooking. Sorry, just being pedantic. 

You are missing the point. Regardless of the thermostat kicking in and out, the energy input required to cook the meal is the same, regardless of the device you use. If it takes 2.8kWh to cook the meal adequately, and your conventional oven only delivers 2.2kWh or less in an hour, then you will either have to cook it for longer, or eat your beef casserole on the rare side. Your choice.

Will it not also depend on the heat loss from the appliance? Won't warming up a big oven to heat a small casserole pot result in a lot of wasted energy heating up the oven walls and through heat radiating out from the oven vents? 

matelodave

OK chaps, I think the problem has been discovered without actually going into the minute details of cooking meat.

Thanks to the OP for coming back and letting us know about the bathroom heater