Heating

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rxninja
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Heating

Postby rxninja » Wed Jan 02, 2008 4:12 am UTC

Ok, here's the problem. In a nutshell, my apartment is absolutely freezing and, given that I have old electric heat, my electrical bill is becoming extremely expensive for it. I suspect that I'm not the only one with this problem, so I'm hoping that doing this will help more people than just myself.

I'm interested in doing the physics number crunching behind heat transfer between the outdoors, translating it into electrical terms, looking at the efficiency of my heater (how well the electricity I'm using converts to heat energy), and examining the whole system to see how best to reduce my electrical use and increase the comfort of my apartment. I only know the basics of the physics of heat and of electricity, so I'm hoping that there's someone who knows significantly more than I do that can help make sense of this. I'll do my best to provide as much information as humanly possible.


-I live in New England, so the average outdoor temperature is pretty low. It's safe to assume about 0 degrees celsius if that helps the math.
-The bare minimum setting on my heater keeps the place at about 60F, 15C. The temperature at the thermostat can never drop below this point.
-In my bedroom there is a 47"x45" (120cm x 114cm) window and in my living room there is an 88"x70" (224cm x 178cm) sliding glass patio door that doesn't shut properly. These are functionally the only areas of significant heat loss. The front door leads to the inside of a heated building, so heat loss there can be considered negligible for the sake of the problem.
-My electrical bill has been an average of $60 for the entire summer, jumping to about $80 in October, $166 in November, and $202 in December. Since heat doesn't activate in the Summer and my electricity-related behavior has not changed at all in this entire time period, the increase can functionally be attributed entirely to heat.
-The heaters in my apartment are extremely old, probably manufactured sometime in the 60's. It's impossible for me to get more technical information about them.

I'm really looking for only a few things:
1) How much energy does it take to balance my apartment temperature at 60F, 15C given a "constant" outdoor temperature of 32F, 0C? How significant is the difference between this energy loss and balancing it at 65F, 18C, or 70F, 21C? How beneficial is it to keep the thermostat down, compared to other means?
2) Given the electrical bill compared to the heat loss results, how efficient or inefficient does my current heating system seem to be? How beneficial would it be to invest in a space heater instead, is there an efficiency boost between a space heater and an old wall heater, and, if there is a higher efficiency in electricity to heat conversion, how much electricity would it save (especially in comparison to keeping the thermostat low)?

There are quite a few guides online to making one's apartment more electrically efficient in the winter time, but I'm not interested in everything that I can possibly do to improve things. I have a limited budget and limited time, so I'm more interested in the best things I can do for my time and money in order to reduce my electrical bill and keep my apartment warmer.

Let me know if there is any more helpful information that I can provide. I don't readily have apartment dimensions at hand, for instance, but I could spend some time researching that if it's something that's necessary. Also, I apologize if this is a bit much and I completely understand if it's not possible at all. My bank account is just getting raped by this electrical bill and I'm freezing my ass off on a daily basis, so I'm somewhat desperate for help.

Thanks!

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blondezilla27
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Re: Heating

Postby blondezilla27 » Wed Jan 02, 2008 6:13 am UTC

To start, get your landlord to fix the sliding door. Also hang blankets over the windows and sliding door, maybe even roll up towels to stick in the cracks. For an alternate heat source, my family used an old-fashioned kerosene lamp when I was a kid. They're really good for heating and lighting a smaller area.
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LoopQuantumGravity
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Re: Heating

Postby LoopQuantumGravity » Wed Jan 02, 2008 7:09 am UTC

blondezilla27 wrote:To start, get your landlord to fix the sliding door. Also hang blankets over the windows and sliding door, maybe even roll up towels to stick in the cracks. For an alternate heat source, my family used an old-fashioned kerosene lamp when I was a kid. They're really good for heating and lighting a smaller area.


When I lived at home, I lived in our recently finished unheated attic (maybe 600 sq. ft?). My parents got an electric heater from wall mart or somewhere, and it worked well enough I could keep my room at a comfortable 75-80 degrees :D. And it was cheap enough that my parents didn't complain to turn down the heat.
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ATCG
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Re: Heating

Postby ATCG » Wed Jan 02, 2008 7:29 am UTC

I definitely second blondezilla27's recommendation on the sliding door. Air leaks of any sort will suck your bank account dry. I would go so far as to suggest taping plastic sheeting over your windows and exterior doors, being sure to seal the edges well. (If it helps, pretend there's been an anthrax attack.) You can also have measurable air leaks through wall sockets, switch plates, and other wall penetrations. Home Depot has kits for these.

Kerosene heating can be very efficient, but I would be wary of carbon monoxide poisoning, particularly since you need to seal your space even more than it is at present. If you go that route, invest in a CO detector.

An electric heater, even an old one, is going to do a near-perfect job of converting power to heat. You need to concern yourself with what becomes of that heat. I would point out that the goal is not to heat the space, but to heat you. Any heat rising to the ceiling or collecting in pockets not occupied by you is effectively wasted. Retreating to your bedroom with a space heater may make sense. Another option that is amazingly effective, but possibly cost prohibitive, is an infrared heater for spot heating. Such a heater trains its output where it's needed - on you - and can keep at least one side of you quite toasty.

Finally, to answer one of your questions, the power consumed (in other words, the rate at which your bank account is emptied) in maintaining a given indoor temperature, assuming it's uniform throughout your apartment, is going to be more or less proportional to the difference between the indoor and the outdoor temperatures. So if it is a constant 32F outside and you want it to be 72F inside, expect to pay roughly a third more than if you roll back the thermostat to 62F.
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The Ethos
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Re: Heating

Postby The Ethos » Wed Jan 02, 2008 3:03 pm UTC

I can't believe I'm saying this, but, "Put a sweater on if you're cold."

But seriously, wearing a hat (winter, not baseball) indoors can just make you feel much warmer. Other then that, make your landlord install more efficient windows (or shrink wrap yours, a fun activity), have a really thick comforter that you can use on the couch/computer chair/etc. Get a throw rug for the bedroom/bathroom floors so that you aren't barefoot on them in the morning.

Don't do the math on your heater vs apt. efficiency. It will only depress you. Best of luck!

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asad137
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Re: Heating

Postby asad137 » Wed Jan 02, 2008 4:46 pm UTC

rxninja wrote:1) How much energy does it take to balance my apartment temperature at 60F, 15C given a "constant" outdoor temperature of 32F, 0C? How significant is the difference between this energy loss and balancing it at 65F, 18C, or 70F, 21C? How beneficial is it to keep the thermostat down, compared to other means?


You haven't given the right information to solve the problem -- you gave dollar amounts -- USELESS! You need to give energy:

The only way you could calculate that is if you knew the effective thermal conductance between your apartment and the outside world. You can estimate the thermal conductance by figuring out how much energy you use in the winter (i.e. look at your summer vs. winter electrical bill -- but ignore the dollar amounts. Look at the difference total energy consumed, in kW-h). Take that difference, divide by the billing period for the winter bill -- that's your average heater power consumption. Then recall that the basic equation for conductive heat transfer is

P = k * delta-T

P you just calculated, delta-T you assume or measure, therefore you can estimate k. Then, using the same equation, you can use that k and different delta-T's to find the resulting P. Then you can just look at your electric bill rates and figure out how much extra money you'll spend.

Note that this ignores radiative heat loss, which has a different scaling than conductive (T^4 vs. T).

Asad

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genewitch
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Re: Heating

Postby genewitch » Wed Jan 02, 2008 10:56 pm UTC

rxninja wrote:Ok, here's the problem. In a nutshell, my apartment is absolutely freezing and, given that I have old electric heat, my electrical bill is becoming extremely expensive for it. I suspect that I'm not the only one with this problem, so I'm hoping that doing this will help more people than just myself.

<tldr'd>


do what i do. get a small portable heater for when you absolutely can't survive the cold, and wear sweaters/jackets the other times. it's my god forsaken roommates that can't manage without a heater cause they haven't learned the beauty of sealing stuff off with $2.50 twin sized sheets from walmart. my room is easily 10-20 degrees F warmer than the rest of the house at any given time currently, and the house is probably on average (excepting my room) 5-15 warmer than the outside with no heat on, IF that.

26 degrees F (which is below 0 for you celcius freaks) last night and my "special" roommate and i just moved closer and got an extra blanket. It was almost stiflingly warm. Getting up this morning and making her lunch was painful, though.

the short answer, wear a sweater. or two. it's roughly $135 cheaper than your electric bill's overall monthly increase.
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umbrae
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Re: Heating

Postby umbrae » Sun Jan 06, 2008 12:40 am UTC

Shring wrap kits are relatively inexpensive and can be very effective.

http://www.acehardware.com/sm-shrink-wi ... 27449.html


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