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In the winter I am in the habit of opening my oven door once I am done baking so that I can add the heat to the house. However I recently thought about it and it would seem that even if the door is closed, and the oven insulated, the only way for the oven to cool would be to heat the house. So this would mean that there is no benefit to opening the door in the winter and keeping it closed in the summer.

So my question is: Does opening the door of a hot oven heat the house more effectively than allowing it to cool with the door closed?

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3 Answers 3

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It depends on what do you mean when you say effective. You are absolutely right when you say that the only way for your oven to cool is by diffusing and radiating its heat to your house, regardless of whether its door is open or not. So the total heat energy transferred from your oven to your room is fixed. But when the door is open, the power, or energy per unit time, is larger.

The word "efficiency" is usually used to denote the amount of energy produced divided by the amount invested, and is not appropriate in this context.

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One should also observe that keeping a room at comfortable temperature is also a matter of equilibrium in the rates of heat gain and heat loss, and "comfortable" is a subjective measure. Opening the oven door will temporarily raise the equilibrium temperature to a level easily sensed by our body, whereas the slow release of a closed door will raise it slowly for a longer time but will probably not be perceived as an improvement by our body. –  anna v Dec 18 '11 at 8:13

The oven has a certain amount of heat energy. It will release that as it cools to be in thermal equilibrium with its surroundings.

The net amount transferred to the house itself, will depend on a couple of things:

Firstly, is the oven, as a system, completely contained within the house envelope, or does it have some direct connection to the outside? For example, if there's an open hearth behind your oven, or if the oven has a flue, the oven system is open to the outside, and some of the heat will be lost to the outside. In that case, to get the most heat into the house, rather than going outside, you need to speed up the rate at which heat is transferred from oven to room, by enabling convection as well as conduction and radiation, so open the oven door.

However, if there's no rapid heat loss directly to the outside, and if opening the door would make the house warmer than you'd want it, then keep the oven door closed: you'll still get all the heat eventually; whereas if you open the door, you'll over-heat the house and just make it less comfortable; in doingso, you'll also temporarily have increased the rate at which the house loses heat by conduction through the external envelope (heat losses being proportional to the difference between internal and external temperature), so you'll have wasted some more of the heat.

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Since your oven is probably connected to the outside air by a vent, heat will likely leak outside over time and never make it to the inside of your house. I would seem more "efficient" to open the door and get the heat inside the house before other losses could decrease the amount of heat added to your house.

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This would be dependent on the oven type. I assume you're talking about gas ovens; the electric type don't have any need for exterior ventilation. –  Dan Neely Dec 19 '11 at 15:52

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