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  • From: "clanSkeen" <sgian AT planetc.com>
  • To: <knat AT sprintmail.com>, <homestead AT lists.ibiblio.org>
  • Cc:
  • Subject: Re: [Homestead] Heat Question
  • Date: Sun, 7 Nov 2004 08:47:16 -0500



If one had a room with less glazing than needed to heat it optimally (warm only at 2pm on a sunny day so supplemented by woodstove) and one put black 55 gal drums of water in front of the glazing that is there. Would it make the room colder? Why or why not?


It's a trick question.

After the sun has been shining on the barrels all afternoon and then the sun goes down, the room is going to be warmer than it would have been had the barrels not been there. If the room cools off to, say, 45 degrees and you have a wood fire in the room the next morning, the room will be cooler than it would have been had the barrels not been there because the water in the barrels will be absorbing some of the heat that would otherwise have just been warming the air. It takes much, much less heat to warm air than it does water. But then again, if you let the fire go out mid morning [before the sun is shining through your window, say]. Then the room will be warmer than it would have been had you not had barrels in it. The water will have absorbed some of the room heat and it is lending it back as the air in the room since air also cools off much faster than water does.

But the real question is: Is the AVERAGE temperature in the room higher with the barrels or without them. To see why this is a trick question consider this: you have a five gallon pot on the stove and a one pint jar with which you are going to fill it from the sink. If you leave the sink running when you fill up the jar and take turn a few steps to empty it into the pot, will you run more water down the sink than you put in the pot? It depends of course mainly on how fast the water is coming out of the sink spigot. If it is a small dribble of water, the amount you lose down the drain will only be a tiny fraction of what goes into the pot. But if the water is on full force with the result that it only takes three or four seconds to fill the pint, then you are losing more water down the drain than you are putting into the pot.

The key here is your insulation and how fast heat is lost through the window. If the temp swings in the room are great and stays cool for large part of the day, the water has so much more capacity to store COLD that you are actually making the room colder with it. If the temp swings are not extreme and the room does not stay cool for a long part of the day, your barrels are making the room warmer.

James





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