most efficient electric heaters

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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #32
    Re: most efficient electric heaters

    You do realize of course that you are in essence rearranging the deck chairs,,,

    By modifying how the heat is dispersed (faster/slower/up/down) etc you are not changing the basic equation. BTU=KWH.
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  • System2
    System2 Posts: 6,290 admin
    #33
    Re: most efficient electric heaters

    I've been looking for efficient electric heaters too and while I understand, from reading this thread, that none are more efficient than any other. It's makes me think the wrong question keeps getting asked. I have electric heat and live in a small attic apartment and I'm just tired of my central heating blowing cold air all the time that I'm about to purchase some other form of electric heat.

    I only need to heat two rooms. I very small 12x20 bedroom with fairly low ceilings (7 feet at most) and the main apartment which is maybe 20x60 with some closets and small hallways that do not need heating.

    I guess the real question is to ask what is the least amount of electricity to heat the air in these spaces?

    I own a light bulb heater which will completely heats the bedroom to a toasty 70 degrees. It only uses a single 60 watt mini flood light with some ceramic planters pots positioned over the top. So I'm assuming 60 watts will heat my bedroom so I'd say 2 more should heat the rest of the apartment. That's a total of about 180 watts. The only catch is that these heaters need to run a good 1.5 hours or so before they really start to heat up the room so on a cold day you would need to run them about 16-18 hours each day. Also, they produce light from the floor which can get on your nerves if you don't place them strategically.

    If all heaters are just as efficient as the other then why do these light bulb heaters heat my room, yet the 3x60 watt bulbs in the ceiling fan of the bedroom don't even heat up the glass they are in?


    To put this into a question for you guys...

    Lets say it costs me 1.5Cents to run a 60 watt light bulb for 1 hour. That means 3 of those heaters would only cost me 72Cents per day @ 16 hours per day, correct?

    Now if I run two space heaters that only use 600 watts each, one in the main apartment and one in the bedroom for 8 hours per day that comes out to like $2.40 per day?
    At 16 hours that's like $4.80 per day, right?

    Even if I run the 3 light bulb heaters for 24 hours per day it still only comes out to about $1.08 per day.

    Forgive me if the math is wrong but, if it's correct then I think I'll build me two more light bulb heaters.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #34
    Re: most efficient electric heaters

    gpm,
    even putting a fan on such a heater will cause you to feel cool due to the air movement even if that blowing air is 80 degrees or more. this is what i dislike about forced air furnaces too and is why the infra red types appeal to me as it radiates the heat and objects that absorbed the initial heat wave reradiate that heat on a different infra red area. no big air movements to cool you off and no need to be on the ceiling to feel the bulk of the heat. ceramics use both the radiant heat as well as forced air passing through them so this is a mixed bag to me.

    brightico,
    if you can heat your bedroom with a 60w bulb then you don't even need a heater. you could then take a bath or a shower and need to open the windows because your place is over heated. i can imagine what would happen if you cooked something with gas or electric. i think your place may be insulated fairly well and the heat from the lower floors are keeping you in much more comfort than you realize.
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  • System2
    System2 Posts: 6,290 admin
    #35
    Re: most efficient electric heaters

    brightico,
    if you can heat your bedroom with a 60w bulb then you don't even need a heater. you could then take a bath or a shower and need to open the windows because your place is over heated. i can imagine what would happen if you cooked something with gas or electric. i think your place may be insulated fairly well and the heat from the lower floors are keeping you in much more comfort than you realize.

    It's about 58-60 degrees in my apartment when I wake up and, it pretty much stays at that temperature all day without any form of heating. The light bulb heater can take my bedroom to 68-70 in maybe 2 hours. You certainly can't do that by showering or cooking unless you cook for 24 hours a day.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #36
    Re: most efficient electric heaters
    brightico wrote: »
    It's about 58-60 degrees in my apartment when I wake up and, it pretty much stays at that temperature all day without any form of heating. The light bulb heater can take my bedroom to 68-70 in maybe 2 hours. You certainly can't do that by showering or cooking unless you cook for 24 hours a day.

    actually you can as hot water and cooking can release more btus in a shorter period of time than your light bulb heater will. btw, the heat energy we are talking about from the bulb is primarily infra red, but there's just not allot of it in a 60w bulb.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #37
    Re: most efficient electric heaters

    It always comes back to the comfort factor: can one type of electric heater be deemed more efficient if it makes the environment more comfortable for the same Watts used? A highly subjective criterion.

    Consider some of the other heat sources and related issues:
    You could have a 500,000 btu furnace and still live in a cold, drafty house because of heat loss. This is the major problem with any heating.
    In-floor radiant heating may arguably be the best, as it warms floors allowing the heat to rise fairly evenly throughout the whole room. Also, the burner temperatures for such systems are lower so they can use less fuel for the same level of comfort. But again, the comfort factor depends upon retaining the heat, not producing it.
    A forced hot-air system can be great or horrible, depending on if the ducts are clean and properly sized. A bad install leaves you with an energy-sucking monster and a cold home.

    In general, electric heat is not efficient.

    In a way, this issue is related to the tankless/tank-type water heater debate as well.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #38
    Re: most efficient electric heaters

    Back to the same basic question/answer/equation. 1 kwh of electrical energy consumed will put out ~ 3100 btus. It doesn't matter if you get it from a light bulb or a computer or a tv set or a heater!

    If you can heat your apartment with just 60 watts running 18 hours/day would burn ~1.8 kw, three of them would burn 3.2 kw, bringing in ~9900 btus.

    If that is what it takes to keep you warm, do it any way you like, as it isn't going to make any difference. The reason your apartment is so easy to heat is that you are getting a lot of "waste" heat from down stairs I suspect.

    Tony

    The reason the ceiling bulbs "don't even heat the glass" is that the heat is carried into the room quickly so you don't notice the heat. Additionally, since warm air rises, the heat at the ceiling is already being given off to warmer air, and it because it is warmer, it is subjected to more heat loss out the building, because of basic physics. The greater the difference in temperature between heated and unheated spaces, the greater the net heat loss, regardless of Insulation R value. (Obviously Higher R-value gives less total heat loss, but the greater the temp difference (Delta T) the greater the heat loss net/net)


    So in some small way, especially if you have a poorly insulated/drafty room, heat introduced low is going to be more "effective" than heat introduced high in the room.

    Tony
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #39
    Re: most efficient electric heaters

    Tony,

    You remember the "zero heat concept" homes of the 1970's? No heat source! Just that given off by the ordinary appliances and lights already in the home.

    There's a diminishing return on investment with insulation, proportionate to the environment in which it is used.
    (Says the guy with the -40 Winters who thinks R38 is a bit low. :p)
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #40
    Re: most efficient electric heaters

    i agree with tony as he is basically restating what i said. the only thing i differ with what he said is that a kwh is 3100btus as it is actually 3413btus, but i usually round this to 3400btus or 3.4btus/wh.
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  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    #41
    Re: most efficient electric heaters

    :) I like to round it to 3333 that way 3kw adds up to 10,000 BTU. And then if you asking heating guys everything is in ton's, which is 12,000 BTU :)
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #42
    Re: most efficient electric heaters

    One possible fly in the ointment with heating part of a home/apartment... My old family home, we heated the living areas and left the bedrooms and such unheated. On the north side of the home (never any sun)--we had mold problems and had to put a 25 watt light bulb (which I later put on a time to only turn on at night) to keep the mold down.

    The warm parts of the home picked up moisture which tended to condense/run high humidity in the cooler parts.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #43
    Re: most efficient electric heaters
    niel wrote: »
    i agree with tony as he is basically restating what i said. the only thing i differ with what he said is that a kwh is 3100btus as it is actually 3413btus, but i usually round this to 3400btus or 3.4btus/wh.

    Neil, You are right, I was having a brain fart and was too lazy to look it up! My bad. ( knew it was ~3000 (something) BTUS!
    Tony
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #44
    Re: most efficient electric heaters
    Brock wrote: »
    :) I like to round it to 3333 that way 3kw adds up to 10,000 BTU. And then if you asking heating guys everything is in ton's, which is 12,000 BTU :)



    It adds to 9999 BTUs if we are into picking nits! (I never understood tons!)

    Tony
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #45
    Re: most efficient electric heaters
    Cariboocoot wrote: »
    Tony,

    You remember the "zero heat concept" homes of the 1970's? No heat source! Just that given off by the ordinary appliances and lights already in the home.

    There's a diminishing return on investment with insulation, proportionate to the environment in which it is used.
    (Says the guy with the -40 Winters who thinks R38 is a bit low. :p)

    There is no reason you can't do it, but as you point out, you reach a point of diminishing returns. That said, earth shelterer/passive solar, depending on climate can produce a huge percentage of their own heat. Use an air/air heat exchanger for indoor air quality, so that you aren't throwing btus out on a 1 change per hour basis and it gets fairly easy to do. It is a simple calc to figure a tight buildings heat loss pretty simply. The issue is that most houses don't come close to tight, and if they do, they have bad indoor air issues.

    Tony

    PS As for earth sheltering, I find that our place stays much warmer if there is a bunch of snow around/on top of it. Aside from the insulation value of the snow (which is considerable) the snow stops a huge amount of air both from infiltrating, but also from blowing over the side (or roof) of the house. Our back wall is only 6' tall, and in the winter the snow will pile up to the eave, adding a huge layer of insulation to the north wall, and to a lesser extend the east and west walls.
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  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    #46
    Re: most efficient electric heaters
    icarus wrote: »
    PS As for earth sheltering, I find that our place stays much warmer if there is a bunch of snow around/on top of it. Aside from the insulation value of the snow (which is considerable) the snow stops a huge amount of air both from infiltrating, but also from blowing over the side (or roof) of the house. Our back wall is only 6' tall, and in the winter the snow will pile up to the eave, adding a huge layer of insulation to the north wall, and to a lesser extend the east and west walls.

    So true, I remember as kids going out with my dad to shovel snow up against the north side of our house. We would shovel it as high as we could. It made a noticeable difference in the house and more so when the wind was blowing hard. Even once the snow closest to the house melted (like in front of windows) it was still much warmer.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #47
    Re: most efficient electric heaters

    Try this for a trick,

    When it is quite cold, take a garden hose, and mist the north (or windy) sides of your house for several hours. A few hours sprinkling and you can have a 1/2" of ice on the entire wall. Nothing makes a great sealer than coating the house in ice. Now air infiltration anywhere. Seals the window casings and sashes, doors and jambs, framing to foundation. etc. Cuts down on the wind noise as well. In real windy or real dry areas, the ice sublimates pretty quickly, (matter of a day or two, but if the air is still, it can stay for a long time, and you can always add more!

    Tony
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #48
    Re: most efficient electric heaters
    icarus wrote: »
    Try this for a trick,

    When it is quite cold, take a garden hose, and mist the north (or windy) sides of your house for several hours. A few hours sprinkling and you can have a 1/2" of ice on the entire wall. Nothing makes a great sealer than coating the house in ice. Now air infiltration anywhere. Seals the window casings and sashes, doors and jambs, framing to foundation. etc. Cuts down on the wind noise as well. In real windy or real dry areas, the ice sublimates pretty quickly, (matter of a day or two, but if the air is still, it can stay for a long time, and you can always add more!

    Tony

    i don't know if i'd recommend doing that as that could be dangerous. spraying the side of one's house with 1/2in of ice in theory would help, but when the ice layers immediately against the house melt away you could be left with an unbraced tall and heavy sheet of ice that could fall on somebody or something and any shattered pieces could be like knives. snow against the house would be less treacherous and would insulate better. i will do neither as i would need to cover over 25ft tall of wall. there's no good substitute in nature for insulating and caulking.
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #49
    Re: most efficient electric heaters

    Wow, a blast from the past.

    That link to the GlowWarm electric light heater...the base that holds the works looks almost exactly like a base I made for a table lamp in jr. high school shop class. As I recall, I got the plans straight out of a book of "plans for jr. high school shop class projects".
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