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Author Topic: DIY Stove Top Fan - Show me yours  (Read 47007 times)
martin W
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« Reply #30 on: February 02, 2012, 03:40:36 PM »

Lurk, Ivan, thanks for clearing that up... I thought it was just me being dull with the USA supplier... I had the same problem with them being very coy on what this electric module they sold me would actually output in electric mode, I thought it was busted! They stated when quesitoned (after purchase), that they did not test them in electric generation mode - these are the Thermo Electric Modules that they are selling.... facepalm.

anyway I have now bought off fleabay a 3v 8000rpm motor and a plastic fan to stic on it...

I must be loosing it in my old age (41 and 1/2), as I looked 2 days ago and found 2 or 3 3v motors on the bay, there is now about 10 pages of em. wackoold.
I noticed there are some high (ish) torque ones at 400rpm which might be worth a look, but first try out the 8000rpm one.
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Woodstove owner since Feb 2011 Tongue (yes it's finally off the pallet)
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Lurk
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« Reply #31 on: February 02, 2012, 03:45:30 PM »

Ivan - that explains a few things !

 The solder creep - could that be tackled by reversing (flipping) the module say each year- - it only needs a screw driver and ideally new tube of paste... I am trying to come up with a way to remove the heat bridge of the clamp bolts - like oversized holes and then teflon washer under a nut ?? but I suspect that the radiated heat from the stove top to the fins is more of an issue ?
Eitherway - it works as is and has run pretty much all day everyday for the last month and a half.
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Lurk
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« Reply #32 on: February 02, 2012, 03:49:35 PM »

Martin - good luck with the motor - mines the 13000rpm - I think it is running at a few hundred rpm tops - no means of measuring it though. On occasions after the stove is alight I put the fan on, wait a minute or so then give the fan a nudge and watch it slowly build speed as both the base disc heats up and the motor builds up speed - I do like gadgets !
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Ivan
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« Reply #33 on: February 03, 2012, 01:05:07 AM »

I saw some TEG based electric generators for oil pipelines. They did exactly as you suggested - oversized holes with insulating washers under the bolt heads. They also used springs underneath the clamping nuts - to ensure that (within reason) whatever amount you tightened the nuts, they always applied constant force on the TEG.

PS I think the biggest loss of efficiency is probably down to the fact that the cool side of the heatsink is in air at 60+C. I did wonder whether the fan runs faster when blowing in the opposite direction (ie drawing cool air from the room and blowing it towards the back of the fireplace)
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Lurk
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« Reply #34 on: February 03, 2012, 08:00:33 AM »

Ivan

I have tried the fan at various positions on the stove to adjust speed as the stove top temp varies. I have also tried it pulling air from the room over the stove and through the fins - its all a bit subjective but   - so if the fan speed is slow and I have just recharged the stove Ive found if i move the fan toward the front edges and turn it so the fan pulls from the cooler side of the stove it picks up speed quicker as the fire warms up. Then I move it back to a spot facing the room.

I'm trying to find a source of a handful of temp' resistant washers as a thermal barrier (m3.5) and I'm also looking for some of those little tiny terminal crimps (like used on 24vdc control wires) I don't want a bag of thousands - just a handful - times like this I wish I had a friendly sparkie ! The local stores only carry high amp' stuff - even the electrical wholesalers ?
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Lurk
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« Reply #35 on: April 23, 2012, 02:14:20 PM »

Sorry to all those that followed the first link in this thread - I updated the page a month or so back and moved its location on my website - Only just spotted the 404 error - sorted now - I hope to include a new page with the new fans and will post that if its OK with the Admin' chaps...very nice men...  fingers crossed!
Lurk
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dan_c
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« Reply #36 on: April 23, 2012, 04:05:14 PM »

Very nice Lurk, I'm interested in one or two and would love to see a photo of the larger version.

Do you have longevity problems with these like Ivan suggested? Solder related?
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Lurk
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« Reply #37 on: April 28, 2012, 09:37:14 AM »

The larger version of the Fan is now up and running on my stove top - it does move more air about without a doubt, but I have to say three fans running at once and if I had any hair it would be wafting about in the breeze !:-) - link for Youtube here Embarrassed
I think it looks great and works well.
Lurk
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Lurk
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« Reply #38 on: June 15, 2012, 12:36:19 PM »

Just a bit of  a question - having now been out and about looking at differing stoves (taking more notice) I am amazed at the variation in heat at the top plate of stoves burning a similar fuel (seasoned Ash / Sycamore). My two Morso stoves run at between 120 & 260 degrees on the top - the flue pipe reads about 5 degrees different.  I looked at an enameled stove this morning which had a top plate temp of 380 degrees -it felt like the hairs on the back of my hand started curling as I moved the thermometer around !  The owner said this was how he normally ran the stove as it was tucked part way into a chimney - the room was....stifling hot  but each to their own.

Just wondered what other stove users were experiencing and if this was /is typical and I run mine cooler than most ?

lurk
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Lurk
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« Reply #39 on: September 11, 2012, 09:24:40 PM »

In the event anyone is still following this thread - I have sent samples of the two fan types - The Fan-C & the Fan-Ce over to the Environmental Technology Centre at Nott's Uni for some 'independent testing' in short to confirm a few details about performance - heat v's rpm v's air flow type of thing.  It has taken quite a while to get everything sorted and the technicians there are now pulling together a more defined testing brief. Meanwhile, the development of a High Temperature Fan-Ce variant is underway and I hope to get a sample over to the ETC to have the same tests undertaken so that the unit can cope with 380 degrees C.

What I was surprised at was that the little 100mm diameter fan unit was capable of an air flow of 170 m3/hr - I have a picture of it under test with hoods, etc which I will try to re-size and post later.

All interesting stuff  Smiley

Lurk
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dan_c
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« Reply #40 on: September 23, 2012, 10:05:09 PM »

All sounds very interesting Lurk - glad to hear you are still working away on them. I think they look excellent  Smiley

I am still interested in one and ideally wanted a black one - are the current prices on the website correct? They seem a bit pricier than I remember seeing.
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peekaybee
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« Reply #41 on: November 22, 2012, 06:04:41 PM »

Hi There
I am hoping to build a stove top fan. 
Does anyone have any plans for one?
I have looked at the Hi-Z site
are there any other suppliers?
thanks for your help
Patrick
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bongodrummer
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« Reply #42 on: May 30, 2018, 09:42:23 PM »

Hi All.
So I have made a whole load of these over the years. I started with the CPU heatsink based ones, then started making nicer (IMO) looking ones from old chainsaw cylinders.



My next significant modification was to make one with thermal protection, which made them WAY more durable, as the TEG didn't fry when the stove inevitably went too hot  whistlie 
I made a youtube video of my newer design fans with protection: https://goo.gl/3dbaZW - Basically it involves a simple mechanical lift that creates a gap between the stove top and the bottom of the fan's riser plate. I show all the details in the vid - it's easier to show it than explain.   

I also recently started making the fan blades myself (previously I had just bought the spare part fan blade). I made a video of that as well, which you can find in my channel if you follow the link above.   

Peekaybee: I have very extensive build instruction written up and free to access on Instructables here: https://www.instructables.com/id/Improved-Stove-Top-Fan-from-Junk/

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knighty
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« Reply #43 on: May 31, 2018, 06:01:28 PM »

I'm at work right now so just flicked through your youtube vid

one thing with those thermoelectric modules... pressure is important... clamp them really really hard

for CPU cooling I'd have them between two copper plates... (one spreader plate to contact the cpu and one waterblock to for cooling)

I used to clamp the plate/tek/plate sandwich in a vice pretty much as hard as I could before tightening up the bolts

that was the accepted method for pretty much everyone using them to cool CPUs

when you can run your cpu at a constant load and track the temperatures of both sides of the tek you can work out what works best pretty quickly


just thought that might help for anyone building one - clamp em tight, they'll work better that way
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