Ecofan

[CatherineB]

I am more interested in the barter exchange Yamin has with her local joinery - if only I could bake!

(Oh, if only I had a wood burner as well, I suppose) :?

 

[yamin]

Neither do you gain any heat by running one of these fans, though I suppose you might divert some warm air from convecting to the ceiling to more in your face.

Thats exactly the plan Biff - in putting up/taking down the Christmas decs we realised how much hotter it is at the top of the room than the bottom. Of course. But if we can circulate the air cleverly enough, hopefully some of that air will get swirled down and into toher rooms. Noe of this is urgent of course as we are toasty anyway, just one room we'd like to force a bit more into.

They could use a pedal operated fan. If they were slacking, their feet would get burned .

That reminds me of my dads idea (look away Biff), that on long haul flights, passengers should work their TV screens by pedal power - 20 minutes in every hour - TV as long as they want it and lots of anti DVT exercise. Not sure it could be extended to running fuel free planes though..... :lol:

Catherine - barter definitely the way to go as far as I'm concerned - we have had at least a ton of wood so far this winter!

 

[CatherineB]

Yamin, sadly I doubt I could persuade British Gas, even if I could bake enough cakes...

 

[yamin]

Oh no, you've no hope there, you can't stuff an iced madeira through a phone line can you??????

 

[biffvernon]

Or will someone argue that the displaced air is somehow heated up by frictional forces during its movement?

Exactly so. The moving air will slow down with friction converting the dynamic energy into heat. And the squeak, Penners, will vibrate you ear drum, warming up your head.

 

[philpjuk100]

They could use a pedal operated fan. If they were slacking, their feet would get burned .

.

If their feet got burned they would leave "a carbon footprint" on the stove.

 

[JohnB]

That reminds me of my dads idea (look away Biff), that on long haul flights, passengers should work their TV screens by pedal power - 20 minutes in every hour - TV as long as they want it and lots of anti DVT exercise. Not sure it could be extended to running fuel free planes though..... :lol:

You didn't warn me to look away. Mentioning the two evils of flying and the evil one eyed mind control device in one sentence is too much for me to cope with too :evil: :evil:.

 

[JohnB]

If their feet got burned they would leave "a carbon footprint" on the stove.

:lol:

 

[yamin]

You didn't warn me to look away. Mentioning the two evils of flying and the evil one eyed mind control device in one sentence is too much for me to cope with too .

Sorry John, couldn't agree more on the one eyed evil box - though on a 24 hour flight to New Zealand with two 7 year old boys who rarely watch the goggle box it was a fabulous treat for them and sanity for us. Can't defend the plane I'm afraid, other than I'm far too selfish to miss the once in probably 20 years that I'll see my sister again who lives over there. I'd love the time to go by boat though, no jet lag, lovely scenery, wonderful.

 

[FamilyWiggs]

Thus ends my brief career as a physicist.

Not so fast.

In addition to your 'fan squeak' point (a noble clutch of a straw if ever I heard one :wink: ), what about the work involved in blowing a mass of air from one side of the room to another? That work must require a reasonable amount of energy, so not all of the heat energy collected from the stove by the thermocouple can be returned as heat by just the fan motor can it?

Or will someone argue that the displaced air is somehow heated up by frictional forces during its movement?

Isn't some of the thermal energy converted into mechanical energy to turn the fan blades?

 

[philpjuk100]

Shirley it is not the few watts it might absorb that is the problem it is just pushing the heat where it is of more benefit.If you can separate the thermocouple from the base and extend the cable then you could stick the fan at the back of the inglenook and get that trapped hot air out.Looked at "ecofans" on ebay and noticed that the thermocouples and motors are available as spares so although it is nice to be able to repair them it looks as if they do not last forever but maybe the spares could be used to build a bespoke version with remote fans for the inglenook (I better forget that,I have enough projects on the go!)

 

[MdB]

Isn't some of the thermal energy converted into mechanical energy to turn the fan blades?

The Ecofan turns thermal energy into electrical energy (using a thermopile). This is then turned into mechanical energy, sound and heat (the motor + fan). The fan turns the mechanical energy into kinetic energy (of the air), sound and heat. The kinetic energy of the air ends up as heat as it slows and maybe a small amount of sound. All the sound energy gets converted to heat. However, you look at it, all the energy ends up as heat. Overall no heat energy is lost and no heat energy is gained (it is just shifted around a bit) which is fortunate as we don't want to break the laws of physics.

Shirley it is not the few watts it might absorb that is the problem it is just pushing the heat where it is of more benefit.If you can separate the thermocouple from the base and extend the cable then you could stick the fan at the back of the inglenook and get that trapped hot air out.Looked at "ecofans" on ebay and noticed that the thermocouples and motors are available as spares so although it is nice to be able to repair them it looks as if they do not last forever but maybe the spares could be used to build a bespoke version with remote fans for the inglenook (I better forget that,I have enough projects on the go!)

Although this would work, it wouldn't work as well as the original design as the fan helps keep the top part of the Ecofan cool. This is required so as to have the largest differential in temperature between the top and bottom halves of the thermopile. This in turn produces the largest amount of electricity.

 

[skier-hughes]

and there was me just thinking the heat rose, hit the blades turned them and moved the hot air around the room :roll:

 

[biffvernon]

Isn't some of the thermal energy converted into mechanical energy to turn the fan blades?

That's how the device works - but then the mechanical energy gets converted back into thermal energy (at a lower temperature). You just can't defy the laws of thermodynamics.

 

[Penners]

the squeak, Penners, will vibrate you ear drum, warming up your head.

Well I may have got this whole thing completely wrong, but it hasn't been a complete waste of time.

At least I now know why a conversation with Mrs P invariably leaves me uncomfortably hot and bothered.

 

[FamilyWiggs]

Isn't some of the thermal energy converted into mechanical energy to turn the fan blades?

That's how the device works - but then the mechanical energy gets converted back into thermal energy (at a lower temperature). You just can't defy the laws of thermodynamics.

Thanks. I was wondering about that recently when reading some stuff about quantum mechanics and the rather different laws that govern the very small compared to things the size of us. I was particularly interested in the conservation of energy in single particles adopting multiple paths or multiple simultaneous histories. Surely each path requires the same energy to move the particle, so the sum of all the simultaneous paths would be greater than the energy input to move the particle.

Then my head hurt, so I stopped.

 

[LadyArowana]

Is that why an ant can happily carry its body weight and a flea can jump so far and we struggle with 6 bags of shopping?

 

[FamilyWiggs]

Well I don't know about that. I've regularly watched Mrs W carry 6 or more bags of shopping in from the car. I'm very aware of the untold tale of Penners' back and daren't risk it myself. :shock:

I guess the only difference is we can't also hear what the ant is saying... :wink:

 

[biffvernon]

Thanks. I was wondering about that recently when reading some stuff about quantum mechanics and the rather different laws that govern...

Careful now, you'll be thinking there are an infinite number of fans sitting, in superposition, on an infinite number of woodstoves in you room. They only resolve themselves to a singularity when the cat looks at them.

 

[Penners]

a flea can jump so far and we struggle with 6 bags of shopping

Fortunately for them, fleas rarely carry 6 bags of shopping.