Galley stove/ovens

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  • 24 Apr 2018 18:50
    Reply # 6118166 on 1195343
    Anonymous member (Administrator)

    Jami, 

    my guess is that it has been cannibalised from some sort of equipment. The point is that the hot exhaust and the fanned air is separated. Only the metal gills are common contact surfaces. It should not be impossible to make for a metal sheet worker, professional or amateur.

    Arne

  • 24 Apr 2018 11:45
    Reply # 6117529 on 1195343
    Arne,

    can you say what kind of heat exchanger is used in the video?

  • 24 Apr 2018 10:05
    Reply # 6117384 on 1195343
    Anonymous member (Administrator)

    Jami,

    That heater looked good, and suitable for live-aboard use. My ambitions are a bit more humble: I wanted to make a simple heater with max radiating power and minimum convection power (where hot air just rises to the ceiling). If I wanted an alcohol convection heater, I would just have bought the Origo Heat Pal 5100  -  or simply light up one of the Origo 3000 burners. That  would work well if an elephant trunk fan were added to circulate the heat. Adding a flue is for more serious use.

    I think my radiating heater works well now, but I will see if I can make a simpler version. My heater also started with an inverted steel bowl, but I found that without a lid on the bowl (insulated and with a hole in the middle for the flame), it would reflect so much heat back onto the stove that I was afraid that something expensive would happen.

    I’ll get back to this subject later  -  now I am busy on other fronts...

    Arne


  • 24 Apr 2018 06:23
    Reply # 6117197 on 6113905
    Arne Kverneland wrote:     

    A while ago I bought a new  Dometic Origo 1500 (single burner) to see if I could make a good heater of it. I used that one for my trials.

    Have you any results on your heater project? I have an Origo 3000 and I've bee fiddlling around with the idea of using one of the burners as a heater.

    This video has an idea. He uses a heat exchanger and a fan, and leads the burning gases outside. The removable system makes it possible to use the burner for cooking as well. I just don't understand what kind of a heat exchanger he is using and where to find one. 


  • 22 Apr 2018 20:30
    Reply # 6114560 on 1195343

    To take the cone idea a little further:

    The original flame spreader has now become redundant. If the cone has a hole drilled through  it,near the top and horizontal, a thin rod can pass through and lodge in two grooves cut into the top of the cylindrical burner. Then it can be easily lifted out, using a little hook, for more convenient access for lighting.

  • 22 Apr 2018 12:30
    Reply # 6114264 on 6114115
    Anonymous member (Administrator)
    David Tyler wrote:
    Good, Arne. This was the idea that I suggested here, and I'm glad that you've tried it out. 

    Ah, I had missed that one  -  great minds, etc...

    Anyway, I find that this cone is a lot better and practical than any of my earlier contraptions (..forced air of different kinds...), and it is the only version  I have made which appears to boost the burner. I am going to make two copies of it for my Origo 3000 on board Ingeborg.

    Now I have put more details on the diagram, so anyone, even without access to a printer, can make a paper pattern and then the real thing. The sheet of thin copper, which I had lying around, was easy to shape by hand.

    A minor sidestep: I have seen the new Origo One stove here; our dealer has both the 1500/3000 and the One/Two models. They seem identical when it comes burner and fuel canister. I chose the 1500 because it comes with a front rail, which takes the kettle holders (additional extras). These are easy to adjust, and hold any kettle or casserole very securely.

    Arne



    Last modified: 22 Apr 2018 12:32 | Anonymous member (Administrator)
  • 22 Apr 2018 07:20
    Reply # 6114115 on 6113905
    Arne Kverneland wrote:  

    Then I got the idea to streamline the combustion chamber by fitting a cone instead of the washer. The first one was 30mm diameter and the next 40mm. This last one appeared to boost the burner quite a bit, and cooking time appeared to be faster than before. The flame picked up fast after a cold start and the ‘flame flow’ appeared faster than ever before.


    Good, Arne. This was the idea that I suggested here, and I'm glad that you've tried it out. As I said back then, "What I've done may not be the only thing that will [improve the burn], but it seems to work". This cone may be one of the better ones, though a little more work than the penny washer.



  • 22 Apr 2018 03:17
    Reply # 6114023 on 1195343
    Anonymous member (Administrator)

    Hello! Thanks so much for getting back to me and for your comments and further testing, I really appreciate it. Sorry for taking time to respond. I am not on the forums often enough! 

    What materials did we use? 

    Alcohol from NZ no colour, we add a bit of water (10%?)  to burn cleaner (which works). Once I finished the current container I will try neat alcohol with the modified burners. 

    Fittings - stainless steel bolt with the penny washer as per David Tyler's instructions. 

    Pete did think that lifting the washer up a bit might help, yet to try it. 

    Watery eyes? 

    Bad, at the point of crying, while the burner is heating up. Not affecting me so much once it gets going. We noticed a strong smell at the beginning which we never noticed before. 

    Conclusion -  probably go back to standard flame spreader (which we ordered from the UK - SEAMARK NUNN on eBay). After 6 years the flame spreaders are giving up the ghost! 

    Awaiting further development - although once offline for a while I am not sure how I will catch up on it. 

    Thanks so much for helping with this. 

    Cheers - Linda & Pete 

  • 21 Apr 2018 22:26
    Reply # 6113905 on 1195343
    Anonymous member (Administrator)
         

    Inspired by David’s photos and findings below, I had another go yesterday and today:
    A while ago I bought a new  Dometic Origo 1500 (single burner) to see if I could make a good heater of it. I used that one for my trials.

    First I copied David’s setup, with a washer. It made a nice blue flame, but it took a while to ‘gain momentum’. It was not faster than without the washer, rather a bit slower, I think. It could have to do with me using too big washer (a 20 Norw. kroner coin, 27mm wide).

    Then I got the idea to streamline the combustion chamber by fitting a cone instead of the washer. The first one was 30mm diameter and the next 40mm. This last one appeared to boost the burner quite a bit, and cooking time appeared to be faster than before. The flame picked up fast after a cold start and the ‘flame flow’ appeared faster than ever before.

    To help me shape that cut-off cone, I actually used the maths in my mast collar write-up, and the results were plotted into my QCAD program to quickly let me print out a pattern. With the burner on full speed, there was still some yellow left in the (15cm tall) flame, but with the kettle on, the flame was still all blue.

    There is one noise-factor here. I am using a different, yellow fuel with only 80% ethanol in it. It was said to burn cleaner. Still, before fitting washers or cones, there was plenty of yellow in the flame. I will try the burner with ordinary red, 96% fuel, when I have used up the yellow fuel.

    Arne

      

    Last modified: 22 Apr 2018 11:13 | Anonymous member (Administrator)
  • 21 Apr 2018 17:31
    Reply # 6113696 on 1195343

    I also did some experimenting to see if I could make the Origo burn better.  One of the observations I had was that anything you put in the flame path absorbs heat initially and depending on what I put in the path, some things seemed to continuously conduct heat away as well.  I suspect your observations can be explained by the increase of mass in the flame path causes incomplete combustion, at least while the stove is warming up.  So the stove takes longer to get going and during that period you have incomplete combustion.  Pure ethanol shouldn't cause eye irritation in this case, but there are lots of additives that do.  I've found the non-dyed ethanol fuel available for in-home non-vented fireplaces to be much better in this regard than some others.  Although, denaturing methods and laws are different the world over, so experimentation is likely required.

    These stoves rely on a particularly delicate balance of forces.  As David described there is not a lot of draft and mixing in air can be a problem.  However, at the same time the heat reflected back to the canister controls the rate at which alcohol vapor is released and the temperature in the cylinder above the canister also effects how complete combustion is.  Unfortunately, changing one of these factors can have a knock-on effect on the others.  A hard nut to crack indeed.

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