Every summer, I have my own ways of keeping my home cool, and trying not to expend more energy cooling it down after I cook. The thing is, I’m not much of a scientist. I never took physics in high school. Physics confuses the hell out of me, most of the time. I have some of the more general aspects down (mass, inertia, energy), or at least, I can look them up online and try to get them straight in my head.
So I was wondering something, having just used the toaster oven to make hot, buttered Italian bread. In the summertime, I tend to close the toaster oven door and let it cool down slowly. When I boil corn or peas, immediately upon putting them on the dinner plate, I pour the boiling water down the sink and run cold water on the pots to cool them down so less heat gets into my kitchen, in the thought that it will need less energy to cool it down (and give me savings on the electric bill).
But really, does it make a difference if you, say, let the toaster oven cool down faster by leaving the door open? Isn’t it going to release the exact same amount of heat no matter what you do, and won’t it take the same amount of energy from the AC to keep up with it?
I think I’m onto something with pouring the boiling water down the sink, but it occurs to me that I’m wasting my time with the incremental cooling of ovens. Or am I? Any physics geeks out there want to take this one?
I think what you’re doing is correct in theory. If you pour the hot water down the sink, it’ll obviously transfer its heat (measured in calories) to somewhere else besides your apartment. Same thing when your pour water on the pots, the heat gets transferred to the water and then the water goes down the drain before it can heat your home. When your toaster cools down to room temperature, it loses the same amount of heat no matter how fast it cools, but if the door is closed it’ll lose heat more slowly, giving more time for the heat to dissipate out of your home before it gets so hot that the A/C kicks in.
But in practice, even in a very small apartment, I’d think the effect of a toaster oven cooling or pot of water cooling would be pretty trivial. To even remotely affect your cooling bill you’d have to not heat anything up in your kitchen at all.
My mechanical engineering brain will come to your rescue.
The overall amount of heat injected into your house is the same whether you leave the door open or closed. So, your overall air conditioning bill will not be affected. If you leave the door open, your thermostat “on†time will probably grow temporarily, but will return to normal soon. If you leave the door closed, the “on†time will still rise, but not as far, and it will take longer to return to normal.
Unless your thermostat is in the kitchen, these variations are probably too small to be noticed. If thermostat is near your oven, it’s best to leave it closed, because the thermostat will have an unrealistically high reading of your house’s overall temperature, and then over-cool the rest of the house in order to get the air near the stove cooler.
I think you’re right here.
The toaster’s heat will dissipate into the room whether the door is open or closed. If A/C is necessary to cool the room, it is going to be affected either way. The only way to avoid this would be to get the heat to dissipate into something other than your room (say, by putting it outdoors to cool down). But that’s obviously impractical.
An open door will allow airflow to the inside. This may make it cool down faster (and therefore heat the room’s air faster). If your A/C is just barely able to keep up with the room’s heat, it is theoretically possibly that the faster cool-down may cause the ambient room temperature to increase for a short period of time, but overall, there should be no difference.
WRT the drain/pots, left alone, the pots will lose their heat into the air. If cold water is applied, however, the heat will flow into the water, which will carry it down the drain.
But keeping all this in mind, I’d be very surprised if the effect will be pronounced enough to actually impact your electric bill.
Just a thought, I’m certainly NOT a physics major myself, so I won’t attempt what I’m NOT knowledgable to attempt, so I’ll approach this question, as I do most things, from the angle of simple logic.
To effect a noticable degree of change in your cooling costs, you might try a few of these suggestions, they work for us:
1. In the hot summer months, eat foods, such as salads, sandwiches, cold plates, etc,…
2. My husband and I noticed a pronounced difference in our room temperature recently when we changed-out every bulb in our house for flourescent. They don’t put-out hardly any heat, they use far fewer watts, and your lighting fixtures will last much longer, because they won’t be overheated.
3. If you have windows to the outside in a shaded area, try window fans, part of the time. They do great for us. We seldom even run our air conditioning units.
4. My husband also added that depending on whether you have a central unit or an air conditioner, putting an awning or some type of cover that will shade your cooling system, (our’s are air conditioners, and we put up an awning to shade them), will signifigently effect your units efficientcy, thus cutting your cooling costs, and lowering your electric bill.
5. Another, (if you can stand it), is to take cold, or at least cooler showers. This will cut down on the heat and humidity released into your home, and thus make it feel more comfortable because of the lower humidity level, and will cut down the excess heat being exhausted into the room.
6. We run a window fan at night, and do not even need our air conditioning, and our temperatures here have been averaging 90+ in the day, and around the mid 60’s at night, and we stay very cool and comfortable using these basic measures.
7. My husband also said to be sure if you have air conditioning units, to wash them out throughly once every year. This greatly effects their efficiently, and thus your cooling costs.
Hope some of these suggestions are useful.
Shalom,
Elaine
Put the toaster oven outside while you are using it and while it cools down. Run a little cold water down the sink when you empty the boiling water. Otherwise, you’re good to go.
I concur with my fellow Mechanical Engineer – the heat energy in the toaster oven will eventually make its way into your home’s air.
If you’re really interested in saving energy – use your microwave for corn, peas, and the like. It takes a very large amount of energy to heat up even small amounts of water, and a lot of the energy from your range is going into the room air.
Just a little note about your drains:
Since you pour boiling water down your drains, right before doing that, turn on the tap for some cold water to run into the drains before that.
It’ll help prevent your pipes from bursting due to constant heat differences.
That hot toaster oven can make a difference. Keep the door closed. Why?
Radiative heat for one. That is a heat transfer that goes as the difference of the fourth power of the temperature. The glass blocks those frequencies of radiation that are thermal radiation very very well — but your body, your exposed skin, is a very effective absorber of thermal radiation from the hot metal surfaces inside the little wee oven. So in the kitchen, in the vicinity of the toaster you will feel much hotter.
A second, and lesser reason is mechanical efficiency. Your AC, and refrigerator too — both will generate some bit more of mechanical frictional heat, and electrical resistive loss in the windings of the motor as they work a wee bit harder to keep the temperature spike down from the the air heated in the oven. Maybe that’s an insignificant effect for a tiny toaster oven.
A third effect — time of day. If the oven is still cooling as the sun sets and nighttime temperatures accrue, your apartment’s heat balance gains that benefit.
bvw: You’re right that there will be a difference.
Whether that difference translates to any actual savings on your electric bill is something altogether different.
If the difference causes your air conditioner to run an extra 30 seconds, how much money would that actually save? A cent? Less?
Remember, this is a toaster we’re talking about. They’re small and not insulated, unlike the main oven in the kitchen.
I had a friend who used to design heating systems. He told me that he had designed one at Bucks County Playhouse were he used a radiative heat system where the heating elements were heated using super heated steam. This is his story, as I remember it told to me.
Super heated steam is pretty hot stuff, I mean I’ve worked in power plants and heard the true stories of pour souls caught in a confined space when a superheated steam leak developed. Not pretty, and exceedingly painful way to die.
So I doubted his story, but he continued. He said the amount of steam needed was very little, and that the radiative elements mounted high in the tall barn roof of the playhouse would be far enough away that any leak would be not dangerous.
That wasn’t the problem he had had with the design. The problem, so he said, was that the temperature of the elements was just high enough that it produced the kind of frequency of infrared radiation that penetrates flesh a few millimeters before the heating is delivered.
He fixed the problem, he said, just by adjusting the temperature of the superheated steam. Or he could have fixed the problem, if they had let him. But they tossed him and his marvelous new method of heating out. Despite his protestations, and despite the cost savings and efficiencies, the management insisted that an older, less innovative, tried-and-true technology replace him and his system.
And why was that? Because they were cooking the audience.
So, shutting the oven door of a “warming oven” — all that beautifully opaque-to-infrared glass — that’s a good thing.