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Thread: Portable electric room heater

  1. #1

    Join Date
    May 2006
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    North Orange County, Southern California
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    Portable electric room heater

    I have been researching small electric room heaters for my dark room.

    One important item I have noticed about all heaters I have looked at is they require to be plugged into an electrical outlet and NOT a power strip, extension cord or surge protector.

    I do not have an available outlet in my darkroom but I do have an available outlet about 15 feet away.
    I am thinking an industrial strength extension cord would be ok to use.



    Thoughts?

    Maybe suggestions on a different approach?

    Thanks

    Gary
    "People take different roads seeking fulfillment and happiness. Just because they're not on your road doesn't mean they've gotten lost." - H. Jackson Brown

  2. #2

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    Re: Portable electric room heater

    Should work. We have them in a workshop as well as temporary use when sub zero outside in two bedrooms.
    Have found the oil filled type, like old steam room heaters work well. No noise, no fan, one small light on the control that is easy to cover.
    "My forumla for successful printing remains ordinary chemicals, an ordinary enlarger, music, a bottle of scotch - and stubbornness." W. Eugene Smith

  3. #3

    Join Date
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    Re: Portable electric room heater

    An extension cord meant for air-conditioners worked well for me in that application. Nowadays I have a tiny heater for the darkroom in winter; you don't need much in Tucson.
    When I had a basement darkroom in Rochester I used one of the oil-radiator type. That needed some pre-heat time in the winter (ambient temp in the basement in winter was around 52F) but did the job for many years.

  4. #4

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    Re: Portable electric room heater

    I've used a ceramic type heater in my darkroom for decades . . . the same one. It's about a six inch cube. It has a fan, which is needed to project the heat into the center of the room. It sits conveniently on one corner of one shelf. Ceramic heaters are quite efficient.

  5. #5
    Drew Wiley
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    Re: Portable electric room heater

    The radiator convection style ones work best, are relatively safe (much safer than ceramic), and don't have glowing strips or coils, no blowing of dust either, but take a little while to fully warm things up. Anything high-wattage needs a decent heat-resistant extension cord 16 gauge or so, and not silly lamp wire. Ordinary power strips are rarely adequate and might even overheat and catch fire.

    I can be absent-minded enough to walk away and sometimes forget a heater is on. With passive radiant heating, that might lead to an oversized utility bill, but not likely a fire. I'm not being paranoid. Earthquakes are fairly common here.

  6. #6
    jp's Avatar
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    Re: Portable electric room heater

    Use a 12 or 14g super heavy duty extension cord and be fine. They don't recommend power strips or normal extension cords because they are made to varying quality and capacity and most are not up to it and most people don't think about Ohm's law and ampacity when plugging things in.

    If you get one that different heat settings it will safer on the wiring and breakers if you don't run it at max power.

  7. #7
    (Shrek)
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    Re: Portable electric room heater

    Quote Originally Posted by neil poulsen View Post
    Ceramic heaters are quite efficient.
    A common misconception that dates to the marketing campaign of the original cube ceramic heaters. Yes they were marginally more efficient than baseboard heaters, but that savings was 100% due to the fan circulating air better.

    All resistive electric heaters are equally efficient. 1 Watt of electricity produces the exact same number of BTUs of heat regardless of the type of element used. Because any waste is dissipated in... heat. The gains in efficiency obtained from Convectair and similar brands of heater are twofold: by placing the heater away from the outside wall, you can lower the temperature of that outside wall and minimize heat loss through the wall, since heat loss is a function of the temperature differential between the two sides of the wall. 2nd, the electronic thermostats they use maintain a constant temperature for the heater, so instead of heating up to 140 degrees until the room warms up by 2 or 3 degrees and the conventional thermostat shuts off, the electronic thermostat outputs air from the heater at whatever temperature is necessary to keep the room at the set temperature. This again reduces the temperature of the wall it's placed on, and the ceiling, which reduces heat loss by lowering the differential. But it also maintains a constant air flow in the room, meaning there is less of a temperature differential between the floor and the ceiling. This lowered ceiling temperature again lessens the temperature differential which is the determining factor in heat loss through your walls and ceilings. Radiant heaters realize savings somewhat differently, by radiating heat directly to you instead of heating the air which then heats you (convection). But typical plug-in radiant heaters, like the oil-filled ones, heat the walls and ceiling equally as the occupants, negating that savings. The dish-type radiant heaters are more efficient than heating a large room, except they'll dry out your skin and give you a sunburn, plus of course you can't use one in a darkroom.

    To get something more efficient, you need to get away from resistive heaters (like all plug-in space heaters) and go to heat pumps or whatever other technologies are out there now. Radiant floor heating is also very good, with the added benefit that it can keep your house from freezing for several days in the event of a power failure. It will heat your floor to whatever temp it's set at, and nothing in that room can then be raised above that temperature by the heating system. So a 72 degree floor means a 72 degree ceiling, compared to a sporadically 140 degree ceiling with baseboard heaters and conventional thermostats. In 0 degree weather, that's nearly a 50% drop in heat loss through your ceiling.

  8. #8

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    Re: Portable electric room heater

    The problem with using extension cords is that they themselves can become heating elements....Ohm's Law, as stated above.

  9. #9
    (Shrek)
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    Re: Portable electric room heater

    Quote Originally Posted by Dugan View Post
    The problem with using extension cords is that they themselves can become heating elements....Ohm's Law, as stated above.
    The weak points are the two ends of the extension cord, the connections often heat to the point of making the plastic malleable, and of course couches. Many a house fire has been started by a couch pinching an electric cord. I don't worry too much about it if the heater is only in use while I'm in the room, and I have working smoke alarms.

  10. #10

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    Apr 2009
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    Re: Portable electric room heater

    One more immediate concern with electric heaters might be if it will trip your breaker when you start using other appliances in your darkroom. A space heater can easily draw 12 amps, unless your darkroom is all LED and very efficient, something else will likely draw more than 3 amps causing a typical 15 amp breaker to trip. There are tiny space heaters that only draw a couple hundred watts, they don't much but in a small room it's enough to take the chill off.

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