Heat yourself, not entire house

LesU

Heat versus light energy is dependant on how you are generating the light.
As fluorescents are very good at producing light your 400W in will produce about 40W of pure light leaving only 360W in heat.
Do the same with an incandescent and 400W input will produce about 10W of light and 390W of heat.
An electric fire of course is producing virtually all of the 400W.

Reading the above post, it is correct to say that even the light produced will eventually fall on an object and get re-absorbed as heat energy, so as long as the light produced doesn't go out of a window it will still be there in the room as heat.

Cardew

ladylouise62 wrote: »

OK, a non-physics-expert question - are they not using the same amount of energy (I thought that the wattage would describe the amount of energy)?
If they are, then with both producing the same amount of heat, but one also producing more light, where does the energy not put into the extra light go in the Halogen?

This is a serious question, I really want to know.

The starting point to answer your question is The First Law of Thermodynamics.

This put simply states that you cannot create or destroy energy.

The two posts above explain the position.

grahamc2003

ladylouise62 wrote: »

OK, a non-physics-expert question - are they not using the same amount of energy (I thought that the wattage would describe the amount of energy)?
If they are, then with both producing the same amount of heat, but one also producing more light, where does the energy not put into the extra light go in the Halogen?

This is a serious question, I really want to know.

The 'wattage' of an appliance is the rate it converts energy, not energy itself (i.e. wattage is power not energy).

The efficiency of an electrical appliance is usually the ratio of the amount of useful energy used to the total amount of energy used. So, a lightbulb may be 2% efficient, meaning 2% of the energy goes into useful light, the other 98% as heat. Eventually, the 2% of the energy made into light also ends up as heat (eg, when you look at a light bulb, the light entering your eye is converted to heat when it hits your retina).

Likewise a 400W tv causes heat to be put in the room at a rate of 400W, with a small amount of the power having an intermediate state of generating a picture and sound.

Say you have a condensing tumble drier in your kitchen, and the average power it uses is 2kW, then, as well as drying your clothes, you get 2kW of heating aswell. So if your kitchen is cold and you require some heating, it's much better to dry some clothes rather than turn on a 2kW electric heater - you'll get exactly the same amount of heating from both.

londonTiger

SYNERGY wrote: »

So I guess my 400w halogen heater will create the exact same light as four 100w light bulbs too... This room Im sitting in must be very very bright right now... but oh.. look at this, something must be wrong, because it's barely giving off a dim orange light that I would struggle to read a book with.

You're not going to reply because you made a dumb half assed comment and you cant back it up

So I guess my 400w halogen heater will create the exact same light as four 100w light bulbs too..

I think you are getting mixed up a little.

You are comparing a heater with light bulbs.

1x400w halogen heater will produce exactly the same heat as 4x100w bulbs.

However 1x400 halogen heater won't produce the same quantity of light, measured in lumens, candela, footcandle or lux (take your pick for light measurement) as 4x100w light bulbs.

no not getting mixed up here, cardew said that four 100w bulbs product the same heat as a 400w halogen heater.

Given that energy is not lost and only transferred, and that the bulbs and halogen heaters produce heat and light, then if they both produce equal heat then they must produce equal amount of light too.

that was my whole point, they dont produce equal amount of light, so therefore they WILL NOT produce equal amount of heat

I see there is a lot of !!! lickery amongst the mse elites here, cardew is a complete charlatan, and made two ridiculous statements and you stick by him

londonTiger

cajef wrote: »

It is you that is being dumb assed, we are talking about heat not light, as Cardew stated four one hundred watt bulbs will give out exactly the same amount of heat as one 400 watt heater, it is the laws of physics.

dont be a numpty, the energy rated is what the device uses not emits, a light bulb is optimised to emit light, a heater is optimised to emit heat, there is a little bit of light produced by the halogen heater and there is a little heat from a light bulb.. etc but not much.

Derivative

LesU wrote: »

Reading the above post, it is correct to say that even the light produced will eventually fall on an object and get re-absorbed as heat energy, so as long as the light produced doesn't go out of a window it will still be there in the room as heat.

Indeed, however, it is probably better to warm the air directly via conduction/convection, than it is to warm objects through radiation and rely on the object to then warm the surrounding air.

I don't see that anything gainful can come from further discussing the 'heat vs light' debate. It's plainly obvious that a 400W device eventually generates 400W of heat - the issue to worry about is whether or not that heat is produced in a useful form, i.e is it warming your ceiling and quickly escaping via an uninsulated roof, or in the case of a tumble dryer, perhaps sitting in a colder room anyway.

SYNERGY

londonTiger wrote: »

dont be a numpty, the energy rated is what the device uses not emits, a light bulb is optimised to emit light, a heater is optimised to emit heat, there is a little bit of light produced by the halogen heater and there is a little heat from a light bulb.. etc but not much.

and there is a little heat from a light bulb.. etc but not much.

A simple question:

Taking that a tungsten light bulb is 2% efficient at using energy to produce light, what does the remaining 98% energy do, where does it go, what does it produce ?

a heater is optimised to emit heat, there is a little bit of light produced by the halogen heater

Put a 400w halogen heater in a sealed area, it will produce 400w of heat, this includes as you say, the little bit of light.

a light bulb is optimised to emit light,.......and there is a little heat from a light bulb.

Put 4x100w light bulbs in a sealed area they also will produced 400w of heat, they must do.

When talking about light and the heat produced by a halogen heater and the light and heat produced by a tungsten bulb, you are simply talking about energy, electricity, being used to produce an output from different areas of the electromagnetic spectrum.

This is where you are getting mixed up, both produce light, but a different type of light. :rotfl:

The halogen heater produces 400w worth of infrared light and heat.

The four bulbs produce 400w worth of visible light and heat.

cajef

londonTiger wrote: »

dont be a numpty, the energy rated is what the device uses not emits, a light bulb is optimised to emit light, a heater is optimised to emit heat, there is a little bit of light produced by the halogen heater and there is a little heat from a light bulb.. etc but not much.

Whatever, can't be bothered to debate with someone that cannot understand the basic laws of physics.

SYNERGY

londonTiger wrote: »

no not getting mixed up here, cardew said that four 100w bulbs product the same heat as a 400w halogen heater.

Given that energy is not lost and only transferred, and that the bulbs and halogen heaters produce heat and light, then if they both produce equal heat then they must produce equal amount of light too.

that was my whole point, they dont produce equal amount of light, so therefore they WILL NOT produce equal amount of heat

I see there is a lot of !!! lickery amongst the mse elites here, cardew is a complete charlatan, and made two ridiculous statements and you stick by him

I see there is a lot of !!! lickery amongst the mse elites here, cardew is a complete charlatan, and made two ridiculous statements and you stick by him

When you have to descend to insults it speaks much of your debating skills.:(

I neither stick by, nor side with anyone, I put my point or view or opinion in a discussion be it right or wrong.

However I am prepared to be shown when and where I may be wrong and have the humility to accept the fact and thank those who point me in the correct direction.

MattLFC

I've not used the gas boiler (or indeed any gas) since I bought my apartment back in March 2010. It's a newbuild, and seems to be warm constantly. On Christmas day last year, when it was -12 locally, the temeprature of the my living room was 17.4 degrees when I got up iirc. And within a few minutes, having the TV, kettle on etc, and body heat, it was soon back past 20 degrees. Mind you, I do have a 500 litre fishtank that runs at 24 degrees, so being such a warm apartment helps keep the eletric bills down on that I suppose.

And it's solar-powered electric and hot water incase you're wondering how I get a shower/bath without hot water lol.

Quality insulation is certainly the way forward. I took npowers sign online 21 tariff, and paid £5 per month on the gas, and it will be coming up to get the £100 dual fuel discount in March, when I will get the discount, plus every penny of the £5 per month I've been paying back, given I've not used a penny gas lol. They won't be happy (iirc the discount was only £40 for electric only lol). When I was submitting the meter readings, the lady on the phone was expecting the usage to start in November, which I played along with lol.

But reqind a few years back, and my old place had underfloor heating, which was temperamental to say the least; when that failed every couple of months, during the winter, I'd resort to an extra few layers of clothing, and it seemed to work a treat. The repeated failiures and the lure of a newbuild were some of the things that forced my hand to buy the new place.