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Old 10-21-2008, 08:12 AM   #11
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Originally Posted by theholycow View Post
The more humid air can feel warmer at a given temperature.

I didn't run my dehumidifier this summer, but I remember it producing cooler air, and I assumed that it must radiate its waste heat out the back somewhere, since the condensed water isn't warm.
The water is actually colder. The de-humidifier uses a compressor like a fridge or A/C. The heat exchange gas is compressed, becomes a liquid and gets hot from this compression. A fan blows room air on the hot coils to lower it back to near ambient. It's this 'heated' or 'waste' air that can raise the true temperature on the space. The compressed / liquified gas is then allowed to expand. It cools as it expands. Since it was nearly at room temperature it cools to below, and hopefully below the dew point. The moisture in the air forms drops of sweat on these coils, which collect and drip off. These drops of water are cooler than the air because they were formed on cold coils.
The sensation of you feeling 'cooler' is due to the more rapid evaporation of body moisture. A dry bulb thermometer will prove that the air blown away from the de-humidifier is at a higher temperature than the room, but a hygrometer in that same air will indicate a lower temperature.

Another consideration when selecting spot heating devices is a 'wind chill' effect from portable heaters with fans to circulate air (or ceiling fans). Don't sit in the draft or you'll feel colder by having body heat blown away.
Ceiling fan air flow direction depends on where you are sitting in the room. If your chair is near the wall and the ceiling fan is in the middle of the room, have it blow downward. There'll be slower air speed and less "wind" effect near the walls than if an upward flow washed across the ceiling and then down the walls. But if you are seated under the fan, then an upward flow will have less "wind" effect.

It was 48F in the house yesterday morning. We agreed it's time to start the furnace. 55 with a set back to 45 at night.
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Old 10-21-2008, 12:23 PM   #12
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The cheepest way to keep warm is with an IR lamp. I have a 250 watt uncoated heat lamp that I run on a 15amp router dimmer/speed control and if I adjust it to about half it glows red and gives off some light and can keep my entire body warm in a 60 degree room. It draws about 80 watts on the Kill-a-Watt meter. I would recommend the coated bulb however unless you want some light.
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Old 10-22-2008, 08:17 AM   #13
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Originally Posted by Lug_Nut View Post
The water is actually colder. The de-humidifier uses a compressor like a fridge or A/C. The heat exchange gas is compressed, becomes a liquid and gets hot from this compression. A fan blows room air on the hot coils to lower it back to near ambient. It's this 'heated' or 'waste' air that can raise the true temperature on the space.
Exactly. Thanks for explaining it (to the others) for me.

i.e. You get some "waste heat" from the water (which you have cooled from water vapor in the air). You then (presumably) throw that cooler water down the drain (effectively heating up the room from the waste heat you extracted from the water (which you cooled). Plus you get "waste heat" also from just the energy used to run the dehumidifier itself. As a result, dehumidifiers have two sources of heat (the water cooling source of heat, and the energy used to power it source of heat) for your energy dollar.

NOTE: Contrast this with a "vaporizer", that will raise the humidity level in the air, but at a cost of taking heat away from the heating element to cause the state change of water to water vapor. As a result, a vaporizer is actually a LESS efficient (as a heating source) device than a space heater (because a vaporizer looses heat as part of turning water into steam), whereas a dehumidifier is a more efficient heating source (because you gain "waste heat", by cooling the water vapor into water).

And has already been pointed out in this thread, the humidity level in the winter is a balancing act. If you have very dry winter air in your house, you probably don't want to take advantage of the extra heat a dehumidifier can produce.

In my case, I generally like around 40% humidity ideally (a nice mix between allergens and "too dry" air), but I don't always get that target (some times I'm a bit lower, and sometimes a lot higher). One way I do avoid going "too dry" though, is how I set my dehumidifier in the winter. I'll adjust it to heating comfort I want, but I'll never go below a setting of 35% on the unit itself (like most decent dehumidifiers, it has a built-in humidity meter to control it's on/off cycling). If the air is already down to 35%-40% humidity, then I will use some other source of heat that doesn't dry the air out as much (such as an electric space heater) and/or I'll add more humidity to the air (for example, by leaving waste water from a bath sitting).

NOTE: The lower you set the target humidity level in your dehumidifier, the more the device will run, and therefore the warmer it will make the room. So as you want more heat, you should adjust the target humidity down (but not any lower than you want for other comfort reasons), and as you are getting warm you should adjust the target humidity up (so the device runs less).
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Old 10-22-2008, 08:34 AM   #14
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Caulking guns can be found at dollar stores these days. The dollar store caulking guns I've used work surprisingly well.

Silicone caulk is not cheap. Latex caulk is cheap and ought to do the job fine, but it's not as nice of a material to work with. It does have less odor than silicone but it isn't as sticky, isn't clear (though it is paintable), doesn't stay as flexible, and doesn't remove as nicely.
I suggested the silicone because: it's water proof, it doesn't crack (i.e. it's flexible), it's practically invisible (if you get the clear stuff), it will last for years, and is easy to remove if/when you ever need to. But you are correct that it is neither the only caulking option, nor the cheapest option initially.

OTOH even silicone caulk (while still many times more costly than some other options) can easily be had for $5/tube (and if you look carefully at some big lumber yards, you can often find the stuff for less than $3/tube). And you can fill a lot of air cracks with even a single tube of caulk. So even if you got 3 tubes your first year, you are still paying under $20 for the project (and you will likely save more than that, in lower heating bills, the first year alone).

So my thinking is why not just get "the good stuff" the first time, instead of buying (cheaper) caulk that you may have to replace/patch in a few years.
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Old 10-22-2008, 08:44 AM   #15
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The cheepest way to keep warm is with an IR lamp.
By all means do this if you like.

However, an "IR Lamp" is exactly as inefficient/efficient as a normal electric space heater (watt for watt), as they both produce heat using the exact same principle. So unless you can get an IR lamp for less than a space heater (making it a better deal, due to the purchase price alone), I see no real compelling reason to pick it over a real space heater. In fact, you could argue that the space heater is a better choice, as most IR lamps don't have a built in thermostat (to turn the lamp off when you are sufficiently heated), whereas most space heaters do have a thermostat.

i.e. Your IR lamp may be fewer watts than the space heater, but it also produces proportionally less heat. As a result, you make up for the fact that your IR lamp uses less electricity when it's running by needing to run it more to warm up the room the same amount. As a result, the total heat is a wash (i.e. run fewer watts for a longer period of time, or more watts for a shorter period of time, and either way you run essentially the same total electricity).
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Old 10-22-2008, 08:50 AM   #16
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But an IR lamp projects heat radiantly rather than just transferring it to the air around the bulb. The result is that you can sit under it and feel warm as the IR energy is dumped into your external surface, rather than having to bring the whole room up to temperature.

So, if you want the thermostat set at 65F and have "extra" heat in one room to feel snuggly, then a 150W IR bulb pointed at your chair is probably as effective as the 1500W space heater, comfort wise. It doesn't put near as much heat into the room, but transfers about the same amount to your body, which is what counts.
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Old 10-22-2008, 09:07 AM   #17
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Quote:
Originally Posted by DracoFelis View Post
i.e. You get some "waste heat" from the water (which you have cooled from water vapor in the air).
No. That heat was already in the air, you're just separating the water from the air and heat. It's not waste heat at all, it's just heat that was already there.

Quote:
Plus you get "waste heat" also from just the energy used to run the dehumidifier itself.
That's the only waste heat made by the dehumidifier.

Quote:
NOTE: Contrast this with a "vaporizer", that will raise the humidity level in the air, but at a cost of taking heat away from the heating element to cause the state change of water to water vapor. As a result, a vaporizer is actually a LESS efficient (as a heating source) device than a space heater (because a vaporizer looses heat as part of turning water into steam)
The heat is stored in the steam, which becomes part of the air. No heat is lost.

Quote:
And has already been pointed out in this thread, the humidity level in the winter is a balancing act. If you have very dry winter air in your house, you probably don't want to take advantage of the extra heat a dehumidifier can produce.
When it's all said and done, I would say your best bet is to just control your humidity to your liking, and heat as necessary. Your case for the dehumidifier is that, in addition to the heat it makes electrically, it is contributing heat to the air that it just got from the air; that is not an improvement.

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I suggested the silicone because
You don't have to sell me on silicone. Silicone is the best! My dad used silicone the way most dads use duct tape. I was just saying that it's not cheap. You posted accurate prices; the difference is in how each of us defines "cheap".
- $1/tube (crappy latex caulk) is cheap for me.
- $3/tube (WalMart brand silicone -- easier than finding a bargain at a lumberyard and seems to be the same stuff) is kinda expensive.

Maybe it's because I'm stingy, or maybe it's because I use a lot of it when I use it...
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Old 10-22-2008, 10:26 AM   #18
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I agree with the IR lamp idea. A 125 watt IR lamp will keep you nice and warm in a 40 degree office if it's over your shoulder and pointed down at your face/hands. A flex headed floor lamp works well for this purpose.
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Old 10-22-2008, 10:28 AM   #19
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IR lamp, space heater, incandescent bulb, stove-top element, ac/dc converter, christmas tree lights, all are eventually 100% efficient in converting electricity into heat.
The key is 'eventually'. It takes some time for photons striking a surface to add their energy to that surface and that surface to then radiate that energy, but 100 watts is 100 watts is 100 watts.
Of greater consideration is how much of that heat do you want heating you, and like right now!, as opposed to warming the air or walls and then having the conductive heat warm you?
A small heater in a small room is going to raise the temperature more quickly than a small heater in a large room.
This ratio of heat application to the smallest possible mass can be taken to an extreme for maximum effect.
The least costly and most effective method is to heat only the minimum mass needed to add heat to you or to retain as much of your internal heat as possible.
Or in the words of my dad, "Put on a sweater, already!"
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Old 10-22-2008, 10:40 AM   #20
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