November 2011,

 I hankered after a self powered fan for the top of my multi-fuel stove, I surfed the web, window shopped at stove shops and generally avoided buying anything.

Then  found a series of clips on YouTube about a nice chap in the US that had made a 'Copper Top Sterling Engine' - now this was what I was after. I looked for ready made version and these were in the £150 + price range...I spent hours watching little candle powered Sterling Engines made by model engineers whom I admire for their patience...

I understood the basics and set about getting the parts list together . Not having access to 'lotion jars' and thinking also that a larger diameter displacement cylinder with short stroke would make for a better unit - I discovered 'scrumpy cider' was on offer and it came in a good sized glass demijohn container. I had purchased three and had a sever headache as a result for a few mornings.

I spent hours working out how to cut the glass cylinder, diamond cutting discs, glass cutting tools and hot candles etc etc- I used some old jam jars to practice - which as it turned out I ended up using. I purchased 3mm copper plate and screwed rod and made up my 'Improved Copper Top & Bottom Sterling Engine' - I was shown how to solder copper pipe and tinning with a gas torch... and burnt myself on a couple of occasions as a result.

Having determined that this was never going to be a quick solution to my Stove Top Fan desire, I then started to look at how the Ecofan was made. More on that later.  Now my sterling engine had soaked up about 4 days of work all be it over a month, burnt my fingers and caused me quite a bit of anguish, I rushed the final assembly and ended up with a fancy looking slightly tarnished paper weight.  The basics of the engine are sound but it still requires working on to get it to run ! This will include a new displacement piston, crank shaft, connector rods, fan and fly wheel...like I say just a few more hours of work  !

Jan / Feb 2012
Back to the Ecofan research

I used to spend a lot of time looking into how to reduce the costs of bulk industrial packaging - I got pretty good at it I thought. Now the larger of the Ecofan models made over in Canada is in  my view a great design, being simple, minimal parts requiring assembly and it does the job - why the hell it is priced at c£140 I will never understand - if it were under £100 I would never had bothered developing my own version. But the Ecofan was over £100 and the low cost copies left me thinking that there was something taken out, besides I was going to make my own !

So I researched, I read about the Seebeck effect, Thermo Electric Generators and how different metals conduct heat at different rates and which worked best and by what extent etc. Then I set about looking to see what else was available. I came across DIY Stove Top Fans on You Tube made from TEC Module (Thermoelectric Cooler) and CPU heat sinks. All were big lumps of aluminium, with bits of wire strapped on, - see for yourself and search the web. Some are better than others and all work to an extent... allthough one or tow drop apart during the film !

I visited my local PC repair shops and was given bits and bobs which I hoped I could use to develop a prototype Heat Powered Stove Top Fan.  I searched the used parts market for a suitable CPU cooler and found the little gem that is the Zalman 9000 series flower cooler. Once I had purchased one of these, the £40 budget was almost blown(most having gone on copper plate and scrumpy !), I purchased a single TEG module (which blew the budget) and set about putting together a prototype.

Now I tried the TEG on the stove top and used a digital thermocouple with multimeter to get both the stove top Temperature and the output from the TEG - further costs but I thought this little fan would look the dogs danglers ! Try as I might I couldn't get the damn thing to work. I corresponded with the retailer and got little in the way of help until after several attempts he released a useful bit of information.  This was a huge breakthrough, although I now needed more parts to get the prototype to work. If I had a stopped and thought a bit harder I possibly could have got there on my own.... but looking at the failed Sterling Engine I was not going to fail twice and I was getting impatient !

I butchered the CPU cooler, breaking the original fan / motor, so I fitted a smaller version from the parts given to me from the local PC Shop http://www.cbits.co.uk/   I used the only bit of Aluminium plate I could get a friend to part with..


Here is what I made:-