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If I have a computer and a heater coil that consume exactly the same amount of energy, which would be more efficient at heating my room? This is assuming that they both have the same fans and heat dispersion characteristics.

And if the answer is that they are the same, then why don't we change all of our personal household heaters into computers?

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I don't know the numbers, but considering a room heater is designed for heating, and a computer's heat is just a side-effect of all the current running through it, I'm guessing that the heater is far more effective. – Kitchi Feb 10 '13 at 9:49
up vote 4 down vote accepted

They are almost identical.

If the incoming energy is the same then all you care about is how much of the input electrical energy can escape from the room - everything else will become heat. Even the fan noise becomes heat when the sound energy hits the walls.

The only part that potentially can escape is microwave emissions from the CPU clock.

Computers are just slightly more expensive than electrical heaters

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I love that the CPU is giving off microwaves! that's pretty cool. Thanks! – portforwardpodcast Feb 11 '13 at 4:53

I would second Martin Beckett. From a physical standpoint, it is possible to claim that the heater is optimized to generate heat in the best part of the spectrum, but at the end of the day, if the goal is to just heat, then the heater is more cost effective. However, from an economical point of view, the utility of the computer is greater then the heater, so you might just be better off buying the computer on and leaving it on when the weather is appropriately cold.

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I would third Martin Beckett and second Hal Swyers. In fact I have a server that I keep in the cupboard under the stairs, and it does an efficient job of heating this space. For example if I want to dry my shoes I will leave them on top of the server. This saves me the cost of running a heater just to dry my shoes, and serves my web sites at the same time.

From a practical perspective, computers aren't optimised as heaters and they tend to be bigger, noisier and more expensive than heaters that are designed to just heat the room. Although I could use the numerous computers scattered around my house to heat it, it makes much more sense to just turn on the gas central heating.

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I love drying things with my CPU. You are correct that computers aren't optimized to be heaters, however what if a company sold an expensive heater that payed itself off over the years by contributing computing cycles whenever it was turned on. Super improbable but interesting – portforwardpodcast Feb 11 '13 at 4:55
@portforwardpodcast - that just happened. It's no longer economic to mine bitcoins with PC+GPU because the electricity costs more than the bitcoin. But if you live in a cold country in winter and are running the heating anyway then a company will pay part of your electricity bill in return for your mining work. – Martin Beckett Jan 13 '14 at 5:36
However if you had a hunk of ASIC that had the same properties as a heater, this may become economic again – portforwardpodcast Jan 14 '14 at 4:33

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