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How to use "wasted heat" from electronics to warm the house in Winter

I thought I would make a thread pointing out a common misconception in regards to the heat produced from various electronic components, appliances or light fixtures. In the summer, if your temps are above that which is comfortable for living then items like incandescent light bulbs, TV's (all kinds), computers, and just about any other type of electronics adds to the heat in the house. I'm sure some of you have heard of the "vampire" devices such as cell phone chargers. These "vampire" devices draw current even when there is nothing attached to them (while they are plugged into an outlet). The energy that is drawn is usually converted to heat so in summer this is not ideal.

- BUT -

In the winter, all of these things can reduce the amount of heat you need to warm your house. If you have a room with 6 100 watt incandescent bulbs you are getting about 595 watts of heat from these lights (these incandescents are SO inefficient if you ONLY need heat). Another source of heat which is usable in the winter is from the refrigerator and freezers. Last but definately not least are computers. Depending upon what type of machine you have, these are great little heaters as the CPU gets blistering hot (hence the massive heat sink on it), the hard drives can get very warm as well as the RAM and GPU. Today's average desktop runs a 500watt power supply and if utilized to it's full capacity 95%+ of that energy is turned into heat so by running your computer you are actually heating your house! I try to make use of this cycle and hook up my massive server only in the late fall to early spring as it draws over 1500 watts and pumps out the heat! Monitors produce heat as well (TV's too - CRT/Plasma/LCD/projection/etc).

If one were truly handy you could rig the dryer to blow humid air back into the house instead of venting the hot humid air outside. I would blow the water through a bucket filer of water prior to doing this, but that would be a great deal of heat being re-captured and recirculated back into the house.

I would like to figure out if there is something that can be done with hot water from a shower. I'm wondering if there is a way to capture the heat from the "dirty/grey" water and put it back into a system. If not it should be used in some type of water purification system that will break down all the chemicals (there are a lot of plants that do this very efficiently) so you are left with water suitable for watering a garden.

Well, this thread got longer than I expected. I mainly wanted to point out that we don't have to be Nazi's in eliminating heat producing electronics in the winter months as all this will go to helping heat the living areas!

Take care!


6,367 Posts

!. Most hardware stores sell a valve for you dryer so that you can pump the air back in your house, if you can't find one take the flexible duct off the back and put a filter over it to catch dirt.
2.When you shower,don't let the water go down the drain,wait til it cools,then release it.
3.On the south facing side of your house,open up any curtain/shades etc. and check on the heat gain when the sun is out.

Merry Christmas,Bobzilla

Capability, not scenarios
11,867 Posts
I am an advocate of superinsulation in homes (only works in new construction, unfortunately).

The premise is that most of the heat needed to keep the home comfortable comes from that naturally produced from within: body heat, cooking heat, showers, electronics, and so on.

My own home is not quite superinsulated but it's probably 2/3 of the way. It's sealed incredibly tightly, so much that I need a heat-exchange ventilator to keep the air inside fresh. That's ok, I built it with that in mind, and it means I control air infiltration rather than it simply leaking in through cracks, around windows, and so on.

My heating bill goes up when my 2 kids go off to college. When they're here, they're running computers, watching TV, burning lights. Their body heat and showers also contribute to heating the home.

I can't run the dryer vent into the house, though I wish I could. As it is, I need my air exchange ventilator to reduce humidity so the windows won't sweat. A dryer vented inside would cause big problems for me. But it's a great technique for homes that are drafty and dry: Makes double use of the heat used to dry clothes, and helps humidify the house.

The flip side of all this, of course, comes in the summer, where electronics and other heat make it harder to cool the house.

BTW, another such technique (this is a good thread for pointing out how people can get double-duty from the energy they consume) is to try to do home canning when it's cold enough that doing so helps warm the house.
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