[Greenbuilding] Quartz Infrared Heaters

John Straube jfstraube at gmail.com
Thu Sep 22 11:30:31 CDT 2011


I am with Bob: I believe in the laws of thermodynamics
1 kW in is 1 kW of heat.
In the apparatus you describe, that is what is happening.  You could use a toaster, a lightbulb a plasma TV or a large and inefficient fan, if they all draw 1 kW of electricity, they deliver 1 kW of heat to the  space.
The possible advantage of radiant heat is that more of the 1 kW is directed towards the person, eg, in the end we usually want to keep people warm, not floors or desks.  So radiant heaters can be used to heat people more directly. This is precisely the approach taken by a campfire on a cold night.  The campfire is hopelessly too small to heat all the air, but the radiation from the fire can heat the side of people that faces the fire.  Like campfires, radiant heaters in cold spaces will heat the side of the person facing the heater, but not the other sides.  
So, there is a possibility that using 1 kW of radiant heat will deliver more comfort than 1 kW of heating circulating air.  But in modern buildings with accepted standard of comfort, a point radiant heater is not much benefit, and in most cases no benefit at all.

The technology of making electric heat is irrelevant: quartz, or halogen, or heated tungsten wires, or fluorescent bulbs will all produce as much heat as they draw from the electric socket.

Heat pumps are the only way to change the efficiency from 100%.






On 2011-09-22, at 12:13 PM, Bob Waldrop wrote:

> I am not an expert on electrical heating devices, but the laws of thermodynamics dictate that it is physically impossible to get more than 1 kwh of heat out of 1 kwh of electrical energy.  in fact, the amount of heat will always be less than the amount of energy expended, whether we are talking electricity, natural gas, wood, propane, whatever.  You can't make a profit, you can't break even, you can't get out of the game.
> 
> Bob Waldrop, firmly devoted to obeying the laws of thermodynamics, all the time, everywhere,
> 
> -----Original Message----- From: Kat
> Sent: Thursday, September 22, 2011 10:48 AM
> To: Green Building
> Subject: Re: [Greenbuilding] Quartz Infrared Heaters
> 
> And if that "someone" would maybe possibly be willing to explain to the rest of us MATH-FREE? ;-)
> 
> -Kat
> 
> On 9/22/2011 8:00 AM, elitalking wrote:
>> Corwyn writes: For heating areas, or people?
>> 
>> 
>> My comment:
>> 
>> This is for heating people.  However, I do not understand how it works.  A radiant infrared lamp directed at an occupant will deliver heat to the body without heating up the whole space.  However, in this device, the lamp is inside a box that includes a fan to distribute the heat convectively.  The box is warm to the touch, but not hot like a woodstove. My guess is that a lamp is used to heat up copper plates and a fan blows this heat to deliver to space.  Therefore the heat is not radiantly delivered to occupant.  I do not understand why 1kwh electricity would produce more heat the 1kwh of heat.  I know someone on this list does understand these devices.  I hope you are willing to explain it to the list.
>> 
>> 
>> 
>> Thanks Eli
>> 
>> 
>> 
>> ----- Original Message ----- From: "Corwyn" <corwyn at midcoast.com>
>> To: "Green Building" <greenbuilding at lists.bioenergylists.org>
>> Sent: Tuesday, September 20, 2011 5:34 PM
>> Subject: Re: [Greenbuilding] Quartz Infrared Heaters
>> 
>> 
>>> On 9/19/2011 4:00 PM, elitalking wrote:
>>>> 
>>>> 
>>>> Do people on the list have experience and opinions about Quartz Infrared
>>>> Heaters such as Edenpure? Are these better than heat element heaters for
>>>> small heat required situations?
>>> 
>>> For heating areas, or people?
>>> 
>>> Thank you Kindly,
>>> 
>>> Corwyn
>>> 
>>> -- 
>>> Topher Belknap
>>> Green Fret Consulting
>>> Kermit didn't know the half of it...
>>> http://www.greenfret.com/
>>> topher at greenfret.com
>>> (207) 882-7652
>>> 
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>> 
>> 
>> 
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> 
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Dr John Straube, P.Eng.
Associate Professor
University of Waterloo
Dept of Civil Eng. & School of Architecture
www.buildingscience.com





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