Navitron Renewable Energy and Sustainability Forum

CHP (combined heat and power) => External Combustion (Stirling engines / hot air engines / steam engines) => Topic started by: Lurk on January 24, 2012, 12:32:25 PM



Title: DIY Stove Top Fan - Show me yours
Post by: Lurk on January 24, 2012, 12:32:25 PM
Seams an age ago since I started looking at this = DIY Eco-Fan type unit. Anyway, finally got mine up and running and it works a treat and for under 30 worth of bits and bobs and postage. you can see an image and some details here - http://www.peakdistrictcreations.co.uk/about-us/environmental-policy/recycled-stove-top-fan/ - I don't know how to upload an image here so I stuck on my own website. any questions drop me a reply.


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Heinz on January 24, 2012, 12:45:42 PM
That's very neat  :genuflect 
I keep wondering about doing the tin can stirling engine thing, but there's never the time and it would probably be noisy ?

Heinz


Title: Re: DIY Stove Top Fan - Show me yours
Post by: roys on January 24, 2012, 12:50:40 PM
Nice job lurk


Title: Re: DIY Stove Top Fan - Show me yours
Post by: biff on January 24, 2012, 01:06:10 PM
I never seen solar panels fitted as quickly as that lurk
                                                     Biff


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on January 24, 2012, 01:14:02 PM
I edited the many and frequent tea breaks ! The second array on the house front tok three times as long with various problems - but it all worked out well in the end and my explorer is showing hat it is in fact still making kwh despite the gloom in the high peak !
Lurk


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on January 24, 2012, 01:45:34 PM
You Tube video - sorry for poor quality - I'm still getting the hang of the IT ! - It looks ok if you lie down and look sideways !
http://www.youtube.com/watch?v=9na5pB7BgqM&context=C3415104ADOEgsToPDskK3_wmiEEnZXBaJFWMa5xuG


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Tigger on January 24, 2012, 02:13:15 PM
Just click Ctrl+Alt+-> (right arrow) and the screen will flip sideways.  Then just click Ctrl+Alt+^ (up arrow) and it will go back to normal.

Once you get the hang of it you'll be doing it to any open machine that you see in the hope that the owner won't know how to put it right.  Hours of endless fun in an office environment populated by users who know very little :) 

Yes, I know it's childish  ;D


Title: Re: DIY Stove Top Fan - Show me yours
Post by: 2807 on January 24, 2012, 03:01:15 PM
Hello Tigger

Just click Ctrl+Alt+-> (right arrow) and the screen will flip sideways.  Then just click Ctrl+Alt+^ (up arrow) and it will go back to normal.

Once you get the hang of it you'll be doing it to any open machine that you see in the hope that the owner won't know how to put it right.  Hours of endless fun in an office environment populated by users who know very little :) 

Yes, I know it's childish  ;D

:-( doesnt work on my machine - any ideas?  Dell Inspiron running Windows XP SP3

2807


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Tigger on January 24, 2012, 03:04:22 PM
Are you using the 'cursor' keys (the group of 4 for up/down/left/right) rather than the 'greater than' (>) or 'less than' (<) keys?

Other than that, no idea :(


Title: Re: DIY Stove Top Fan - Show me yours
Post by: 2807 on January 24, 2012, 03:08:16 PM
Hello Tigger

Are you using the 'cursor' keys (the group of 4 for up/down/left/right) rather than the 'greater than' (>) or 'less than' (<) keys?

Other than that, no idea :(

Tried both - neither works - but the YouTube video is now the right way up..

Thanks for your help, but I will bow out now - as I don't want to hijack this thread.

2807


Title: Re: DIY Stove Top Fan - Show me yours
Post by: dhaslam on January 24, 2012, 04:03:14 PM
That works very  neatly.    I would like to  do something slightly different, to circulate some  warm air through the  wood store.   A small fan would do it  but the TEG  would need to  run at lower temperatures, something like 150C max on the hot side.     


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on January 24, 2012, 04:25:33 PM
I have a 'spare' TEG to play about with - not sure what temp it needs to run as I understand the principle is heat difference side to side - I will see if I can find my meter and get a warm cup of water one side with something cool the other.
I wasn't expecting to get much in the way of interest - the website hit rate has doubled since lunch time ! I will try to leave you some info'
Lurk


Title: Re: DIY Stove Top Fan - Show me yours
Post by: billi on January 24, 2012, 06:17:40 PM
Lurk  i am  impressed ,thanks .....

I had a go  with these Teg s or similar  but same supplier and was disappointed http://www.ebay.com/itm/POWER-GENERATION-TEG-HIGH-TEMP-THERMOELECTRIC-PELTIER-/280477179086?_trksid=p4340.m263&_trkparms=algo%3DSIC%26its%3DI%252BC%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D15%26pmod%3D310155795073%26ps%3D63%26clkid%3D5840829948160030439

i guess  i should have  gone with the knowledge of  http://thermalforce.de/  whistle

Billi


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on January 24, 2012, 07:20:32 PM
Billi - I too was unimpressed when I first tested the TEG (as per your first link) - I had quite a few email exchanges with the supplier - who shall we say was less than forth coming - however, after getting a bit more info' I ensured that the entire surfaces of both sides were fully contacted by the paste and metal components - then after cocking about with the wrong voltage motor and getting that sorted it all went swimmingly !
 
Couple of extra pointers for the mk ii - I will use a thicker ali' base but with a smaller surface area just to cover the TEG + a bit for stability - ideally it would be 25mm+ may be even 50mm thick - this would reduce the maximum heat transfer to the hot side of the TEG which is only rated to 230degrees C . I have found that the stove top is not exactly 'flat' and so heat build up on the plate is slow due to the point contacts.   A thicker & smaller surface area  would also then allow a larger diameter fan to be fitted forward of the copper fins - so new motor mount necessary.  I've looked all over for a decent small metal bladed fan that will not be to heavy for a 2mm diameter motor shaft - no joy. So I may try to make one from some ali' / copper sheet and fit it to a wood hub.

Lurk.


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Tigger on January 25, 2012, 10:45:14 AM
Lurk,

>>I have found that the stove top is not exactly 'flat' and so heat build up on the plate is slow due to the point contacts.

How about using some heat transfer paste on the base as well?



Title: Re: DIY Stove Top Fan - Show me yours
Post by: billi on January 25, 2012, 10:51:05 AM
Thanks Lurk

So there is some hope for my 10 Tegs   i have  ..... will go playing


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on January 25, 2012, 02:15:40 PM
10 TEGS - are you made of money ?

I have been trying to work out how to fix a large number onto the upper section of the stove flue pipe so that the heat from it can be put to some use. As it is out of sight under the chimney lintel - The problem is ensuring that the TEGS surfaces are fully covered one side by heated metal the other by the 'cooling' side - which brings its own problem being stuck in an alcove and not wanting to fix another cooling fan and use up the limited power generated. The whole assembly has to be removable for sweeping out the soot etc.

If I had some sheet copper that would be a starting point to make a flanged collar to strap to the flue..... alas, the local scrap man has removed all possible local sources !


Title: Re: DIY Stove Top Fan - Show me yours
Post by: billi on January 25, 2012, 05:14:00 PM
Quote
10 TEGS - are you made of money ?   
     ;D investment  was done in  celtic tiger  times .........    whistle      time to buy some heat paste now instead of diesel  for my generator   bike:



Title: Re: DIY Stove Top Fan - Show me yours
Post by: Ivan on January 28, 2012, 02:34:32 AM
Here's my DIY TEG fan - eventually, the solder connections inside the TEG 'creep' causing open circuit. You need to restrict the maximum temperature with a bimetallic strip or somesuch.

(http://s17.postimage.org/6le3m3kkr/PC080003_small.jpg) (http://postimage.org/image/6le3m3kkr/)


Why stop there? How about some LED lighting. These are by the stove for the photo,but I'd actually run these up to the top of the telly mounted on the wall above the fireplace. When the fire was going well, the lighting was as bright as having a couple of low wattage lamps on ( 3 x 1W LEDs). Note the use of the ecofan for cooling the heatsinks by blowing cooler air over them

(http://s16.postimage.org/pwv1yy8dd/DSCF2438_small.jpg) (http://postimage.org/image/pwv1yy8dd/)

My plan was to bank up several TEGs to get enough voltage/power to run the 4Watt wireless internet router that I had back then, but, I never got that far. I did get a low voltage radio to run perfectly happily from TEGs and quite loud too, but not the sort of thing that I can demonstrate well in a picture.


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on January 28, 2012, 08:34:45 AM
Thanks for sharing Ivan, if I could ask, where did you source your fan blades ?
Lurk


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Ivan on January 31, 2012, 02:46:11 AM
The blade is a replacement for an ecofan - very expensive for what it is. You can get just as effective 4-blade fans from China, but I never really developed it any further otherwise I would have ordered some in.


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on February 01, 2012, 01:53:41 PM
Ive made a MK 2 version which you can see here http://www.peakdistrictcreations.co.uk/about-us/environmental-policy/recycled-stove-top-fan/ (http://www.peakdistrictcreations.co.uk/about-us/environmental-policy/recycled-stove-top-fan/) at the bottom of the page. It now starts up quicker and runs very quietly on top of my stove. I have two more TEG units on the way ready to make another couple of fans. I want to make one to strap onto the flue pipe !


Title: Re: DIY Stove Top Fan - Show me yours
Post by: stannn on February 01, 2012, 01:58:30 PM
Lurk
It looks neater with that round base. Does is shift enough air to be useful?
Stan


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on February 01, 2012, 02:34:49 PM
Difficult to say - there is no huge gushing of air - but subjectively the room feels warmer - could be a placebo thingy... I normaly obly run the stove very low heat - where the top plate is just about 80 degrees - the fan needs 85 + so I'm running the vents slightly open to get the fan running - so more heat from the stove anyway.
The Mk2 fan is 85mm diameter - where as the Mk1 was 60mm - you can feel air off the Mk2 on the back of the hand at 12" - I have a 140mm fan unit I am going to have a play with when the next lot of TEGs arrive - but I suspect it will require a bigger drive and multiple tegs to operate....


Title: Re: DIY Stove Top Fan - Show me yours
Post by: murraymint on February 01, 2012, 07:36:11 PM
Is there any way of adapting this idea for normal central heating radiators, I have used battery powered fans before but using some of the heat from a rad works for me.


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on February 01, 2012, 08:36:53 PM
Murymint - I doubt you could get a TEG to operate at such a low temp (40 - 50 degrees at most ?). I think you would want to start with a low temp sterling engine - adapt the fly wheel into a fan some how. - I looked at the 40 units on fleebay but couldn't see an easy way of adding the fan blades without them getting in the way of the drive shafts..... I'm sure someone would be able to work it out.
lurk


Title: Re: DIY Stove Top Fan - Show me yours
Post by: billi on February 01, 2012, 08:53:31 PM
Quote
Is there any way of adapting this idea for normal central heating radiators, I have used battery powered fans before but using some of the heat from a rad works for me.


http://thermalforce.de/engl/product/module/index.php

http://www.thermonamic.com/products.asp?cid=363


I know  prices  for them  ( based on TEG s).....  and  still  am surprised how much they are , for such  a small piece of... what exactly  ?

Guess   the wattage  they can produce is not the problem ,more the heat and cooling  that  we have to supply  is the problem   :P

Not an Copperfield trick  

But still  ideas exist to change waste heat into electricity    :)

Billi  the PV-kid


Title: Re: DIY Stove Top Fan - Show me yours
Post by: martin W on February 02, 2012, 04:06:08 AM
hi, what speed is the motor rated for, as the 3volt ones I have seen are around 13,000rpm which seems a bit fast :o, anyone got a link for 1.5-3volt low speed / low mAmp motor?

I also bought one of the tegs form that ebay supplier who did not impress me with their responsed when i can hardly get 2.5volts out of they supper fandangled teg which they hinted at was 12v. however i now realise I need the lower voltage dc motor say 2-3volts. I also took a tec module out of a beer can pc cooler I had, and it seems to have similar voltage and mA output as the super teg module :(


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk on February 02, 2012, 08:08:33 AM
Hi Martin
yep thats the motor. Yep 12v suggested rate is when the TEG is used as a 'cooler' so you apply that voltage - they are useless at comm's - it was like pulling teeth - I had to write that I had no intention of taking any form of legal action I was just trying to develop a project and wanted advice - I got the impression they were 'rear end covering'.
I get approx 0.2 amps @1.4v at 100 degrees flue pipe temp'
I would love to able to find a low rev high torque low amp 1.5v motor...oh and cheep.... I looked but couldn't.... one other thing - don't try to glue the motor down - I first used a PU foaming adhesive - good and strong but the foam got into the motor and stopped it ! - It took half an hour to strip and rebuild the motor !

If there are more people interested maybe a group purchase of the TEGS - and see if we can get a better price ?

Have fun

Lurk


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Ivan on February 02, 2012, 02:21:35 PM
The only difference between the coolers and the TEGs is the temperature rating of the solder. Even the 250C units will eventually fail on a woodstove, due to 'creepage' of solder ie at temperatures  below the melting point, solder tends to flow very slowly - like glass does in old windows. It takes about 6months, from my experience on a woodstove fluctuating between 120C and 220C.

Mostly, sellers quote the cooling wattage rather than the generating wattage - which is a bit like quoting the heat flowing through the device for TEGs rather than the power it produces.

The TEGs are actually multi-junction thermocouples, with solder tracks on the surface of two ceramic plates. Actually, the TEGs should not have silicone around the edges (they do this for coolers, so that you don't get condensation inside the unit) - but in practice, we're all buying TECs rather than TEGs. You could pull this silicone off, which would improve the efficiency a little by removing a heat-bridge.

If you buy a 12v module, you'll probably get 1-2V under normal circumstances, but if you get a good temperature difference across it (like 100C) you'll probably get 8V or so from it. You need to keep the hot side hot and the cold side cold. Bear in mind that the cold side is being heated by heat flowing from the hot side and the hot side is being cooled by the heat flowing to the cold side. There are difficulties in getting the heat to the hot side fast enough and getting the heat away fast enough. So in practice, when you place your TEG device on your woodstove, you'll have probably 150C on the hot side and 135C on the 'cold' side of the TEG (I did experiments with a tiny thermocouple temperature sensor to find out). To get a good temperature drop across the TEG, you need four things 1)Good heat supply on the hot side 2)Good cooling on the cold side 3)Good thermal contact on hot side (think tightly clamped) 4)Good thermal contact on the cold side.

Remember it generates electricity in relation to flow of heat through the device, not temperature differences between the two sides

So, in MartinW's case, it might be more to do with the temperature drop ACROSS THE MODULE ITSELF, rather than the TEG output per se.


Title: Re: DIY Stove Top Fan - Show me yours
Post by: martin W 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.


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk 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.


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk 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 !


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Ivan 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)


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk 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 ?


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk 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...  :crossed
Lurk


Title: Re: DIY Stove Top Fan - Show me yours
Post by: dan_c 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?


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk 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 :- http://www.youtube.com/watch?v=a21DmDp9Ocg&feature=plcp (http://www.youtube.com/watch?v=a21DmDp9Ocg&feature=plcp)
I think it looks great and works well.
Lurk


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk 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


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Lurk 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  :)

Lurk


Title: Re: DIY Stove Top Fan - Show me yours
Post by: dan_c 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  :)

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.


Title: Re: DIY Stove Top Fan - Show me yours
Post by: peekaybee 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


Title: Re: DIY Stove Top Fan - Show me yours
Post by: bongodrummer 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.

(https://s33.postimg.cc/9oob96yaj/raised_up_fan.jpg) (https://postimg.cc/image/9oob96yaj/)

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  whistle 
I made a youtube video of my newer design fans with protection: https://goo.gl/3dbaZW  (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/ (https://www.instructables.com/id/Improved-Stove-Top-Fan-from-Junk/)



Title: Re: DIY Stove Top Fan - Show me yours
Post by: knighty 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


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Paul_m on September 11, 2018, 01:21:01 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


I've had this on the to do list for a while, there are some plans available online from a blogger called myfordboy THAT looks like its good.  I will need to cast some aluminium for it but should be an interesting project.

https://youtu.be/XzE7pkIknmQ


Title: Re: DIY Stove Top Fan - Show me yours
Post by: Sprinter on September 12, 2018, 11:29:23 AM
Just sent a message regarding your short prototype, that would be perfect for us as we dont have enough room for the other ones if they are still available.