Naked Science Forum
General Science => General Science => Topic started by: paul.fr on 05/12/2008 14:11:28
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How much heat would a "standard" Tv put out over an hour? Would this be enough to heat a room?
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It would nothing like be sufficient to heat a room, but it does add a bit. It is one of the fallacies about switching things off to save power. The power is not wasted if you are heating the room by other means anyway, it simply adds to the heating a little. Most TVs with CRTs are in the few hundred Watt range and modern LCD TVs much less. On standby they are a few watts only. To heat a reasonable sized room on an average winter day in the UK you would probably need between 2 and 6 Kilowatts depending on insulation.
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You can make your TV look like it's heating the room ...
http://vids.myspace.com/index.cfm?fuseaction=vids.individual&VideoID=4995596
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It is one of the fallacies about switching things off to save power.
Yes and no... depends whether your domestic heating system is more or less efficient than the conversion of fuel to electricity at a power station and subsequent transmission via the national grid.
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Rosy, you are making this complicated :-)
It makes no difference to the energy usage of your household (in kW.Hours say) provided you are heating. It does waste power in summer when you may not be.
The energy from different sources (eg electricity vs gas) will not cost the same. In the UK gas is still cheaper (I think) so the heat from leaving the telly on may cost a little more than if you have gas central heating.
The total energy used will depend on conversion efficiency and losses, as you say, though for most people it will be the cost that matters.
Energy supplied via electricity will probably be the way we will all end up (eventually) if we are to reduce carbon emissions. Unless someone invents a safe portable fusion reactor.
Anyway I was just countering a commonly held belief that the energy was wasted, which it is not necessarily.
Ahh, forgot to mention storage heaters where the electricity is purchased at night at lower rates and is just for heating. This will always be cheaper as long as you don't mind the vast amount of heavy-bricks-in-a-box that you need to store the heat.
Go on. I expect I've forgotten something :-)
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I think you would do best to just set light to your TV, saves on electricity and gas and a whole heap of mind numbing tripe!
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How much heat would a "standard" Tv put out over an hour? Would this be enough to heat a room?
You look at the label on the back, and it tells you the electrical power. A typical 14" TV might be around 50Watts, while a 19" set might be closer to 80W or 100W. A 40" plasma screen might be 400Watts.
If you put an 80-100W TV in a very small box-room, and shut the door, you might notice it getting warm after a few hours, assuming the room was well-insulated and draught-free, and the outside-temperature was already fairly comfortable.
On the other hand, if you've ever tried to heat a house with a failed central heating system, during a cold snap, using a 2kW fan heater, you'll know how futile it seems!
A typical UK gas central heating boiler for a modest 2-3bed house is rated at 12-16kW (even though it burns gas!), but the thermostat ensures the boiler is not running continuously (I suppose in the perfectly-scaled system, the boiler might just run continuously on the coldest day of the year).
While all "waste" heat from TVs and other appliances helps to heat the room, gas is generally only 1/3rd the price for the same amount of energy delivered to the home (and with comparably lower carbon emissions), so it does make sense to allow the gas boiler to do bulk of your heating for you.
If your house is electrically-heated (like some new-builds), then you may as well heat using gadgets!
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It's nothing to lose any sleep over; you get what you pay for and you pay for what you get. You could say that you get better value from a hot TV because you got some entertainment as well as some heat from it. The same could be said about lamps; in winter, their 'waste' heat (and the light, too) goes toward warming the room. And, if you say that it's of no consequence, compared with the heating input, then neither is their running cost.
The big old valve colour sets would take several hundred watts - that would keep the chill of any room, left on 24/7.