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I want to vent smoke, such as roasting coffee smoke and cooking grease out of my kitchen. I do not have a hood, nor is there room to install one due to cabinet and window placements just above the stove. I have a window just above the stove, so placing a fan in the window is doable and seemingly effective. But in the winter having a fan suck all of the hot air out of the house is not ideal.

Is the loss of heat, over a 20 minute period of window fanning a few times a week a big deal?

Is there a way for the fan to suck out the smoke without losing too much hot air?

Should I invest in a through the wall vent, and would this be any better than the window fan?

  • For domestic use there are heat exchanger extractor fans (wall rather than window mount as far as I know). Assuming you heat your house for much of the year they might be worth a look. – Chris H Oct 24 '16 at 16:25
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What you are proposing -- to remove the heat energy from the cooking fumes prior to exhausting them -- is complicated by two factors*:

  • Heat engine performance is limited by the temperature difference between the source and sink (more info). If you tried to transfer the heat of the cooking fumes to the ambient air in your house, the temperature difference would result in such a poorly performing heat pump that you'd be unlikely to ever recover the cost of purchase and installation. Alternatively, if you proposed exchanging the heat with outside air, the mechanism to accomplish this (exchanging cooking fumes with outside air before that air is fed to your furnace) would likely be quite expensive.

  • But, the good news is: You're probably not losing that much heat anyways, and you'd probably better off without it! The cooking fumes are already heated to a temperature which is likely higher than the desired ambient temperature in your house - so by exhausting this air, you're keeping things comfortable. This is especially true in the summer!

That said, I'm curious as to whether anyone knows whether large kitchens or industrial cooking operations re-capture the heat from exhausted fumes? It seems like at scale this could be effective.


* I'm ignoring the possibility of separating the gases (smoke from non-smoke), as this would require some sort of purification system, which would clearly draw more power than could be recovered from the heat content of the air.

  • In commercial scale kitchens getting rid of heat is more of an issue than recovering it. In food factories each machine will be reasonably well insulated and open cooking won't be common. – Chris H Oct 24 '16 at 16:24

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