Re: Electric space heater?

D.J. Osborn wrote:

"Lone Haranguer" <linusz@xxxxxxxxxxxx> wrote:


Blow the same amount of air around a couple of skinny electric heating elements and also around a heated chamber with about 4 times the surface area. The greater surface area will allow more heat to be transferred even though the same number of BTUs are available.


The residential electric furnaces I've seen had far more than "a couple of skinny electric heating elements." They had a number of heating elements.

>>>> The heat pumps in our houses have gas-pack furnaces for backup heat,
>>>> instead of electric elements. Makes a world of difference.
>>>
>>>
>>> It doesn't make "a world of difference" at all. The elements in a properly-sized home electric furnace put out the same amount of heat as the burners in a properly-sized home gas furnace.
>>
>>
>> But they lack the heat transfer ability because they lack equal heat transfer area.
>
> What? Your statement makes no sense.
>
>
>> Therefore, there is no
>>
>>> noticeable difference in heating performance between an electric furnace and a gas furnace.
>>>
>>
>> Bull twiddle.
> Another statement that makes no sense.
>
Blow the same amount of air around a couple of skinny electric heating elements and also around a heated chamber with about 4 times the surface area. The greater surface area will allow more heat to be transferred even though the same number of BTUs are available.


The *fact* is that an electric furnace with 75,000 BTU output will have the same heat output as a gas furnace with 75,000 BTU output. If the system is properly designed, then either of them will heat the appropriate house nicely, and a homeowner wouldn't notice any difference in the heat output at the registers.

Now you're talking BTU "output" and "properly designed" How many are wasted of the BTUs available?

Efficient heat transfer occurs if there is more surface area for the amount of air being moved across it.

>>>> The heat pumps in our houses have gas-pack furnaces for backup heat,
>>>> instead of electric elements. Makes a world of difference.
>>>
That's why all the homes here have Carrier units with electric air and gas heat in the same rooftop unit, using the same fan.
LZ
.

Relevant Pages

  • Re: rate of cooling
    ... liquid held heat less efficiently then when cup was ... but heat loss by evaporation is proportional to the surface area of tea open to the air. ... The standard introductory fare on heat transfer is: ...
    (sci.physics)
  • Re: Nav Lights using Luxeon LEDs
    ... Andrew Sarangan wrote: ... surface area is not the only determining factor because the thermal ... conductivity of the metal will limit how far the heat can spread. ...
    (rec.aviation.homebuilt)
  • Re: Continental A-65 engine stall?
    ... vaporization of the gasoline can be as much as 100 times colder than ... that allows you to figure out your probable icing point. ... As for heat muffs, the FAA expects ours to provide a 90F rise in the ... insufficient surface area for the heat to transfer two. ...
    (rec.aviation.homebuilt)
  • Re: Woman Loves Audi A4 more than her son
    ... >> If immersed in hot air, the higher the surface area to volume ... >> the faster the volume will heat up. ... > Well, yes, but you also shed heat as a function of surface area - more ... gain more heat from absorption than you can loose via evaporation. ...
    (alt.true-crime)
  • Re: On Superconductors, Superfluids and Heat Transfer
    ... conductivity -- which requires two *different* temperatures. ... Thomas can't seem to decide what property he ... analogies between superconductivity of heat and electrical superconductors.} ... This doesn't support your claim that heat transfer is infinite -- finite ...
    (sci.physics.relativity)