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Ditmar Demon 70 paraffin stove/heater

Discussion in 'Other Brands' started by presscall, Sep 16, 2014.

  1. presscall

    presscall United Kingdom Subscriber

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    Firstly, my justification for posting this here on CCS and not on sister site Classic Pressure Lamps as a heater ...

    It's down to its efficiency as a stove, simply, four pints of water in that 6-pint kettle reaching boiling point in around 8 minutes

    1410899707-1.JPG


    It achieves that level of efficiency by a couple of expedients:

    - having a burner that uses a (small) wick only to prime the burner by heating up a vapourising loop that once hot enough creates a thermo-syphon to deliver vapourised fuel to the burner

    - the hot gases from the burner are channelled up concentric metal cones to emerge as flame at the top of the stove, heating a perforated metal dome to red heat, the radiating disc being just below the cast iron trivet ring

    1410899716-2.JPG

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    Kettle's boiling here, stove casing just warm to the touch in the lower part of the burner

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    A Svea 100 alongside for size comparison. Also in the picture is the stove lid to pop over the trivet when the stove's a heater

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    Now it's a stove ...

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    ... now it's a heater

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    Component parts

    1410899785-9.JPG


    Burner assembly

    1410899795-10.JPG


    That enamelled drum mounted on the lower burner component contains the concentric metal cones I spoke of. The disc in the foreground goes inside the inner cone, sitting on the crossed securing pins, acting as a safety flap valve, closing off the central vent to hot gases so that they pass between the concentric cones to arrive as a ring of flames at the perforated dome, but flipping up if a surge of hot gas arises so that there's no flaring of the excess at the burner outlet - is my guess!

    1410899807-11.JPG

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    The lower burner assembly has this red bakelite lever. Flipping it from horizontal to vertical half-a-dozen times operates a pump to deliver a charge of fuel (paraffin/kerosene) to the priming wick. Once that's done it's flipped back to the horizontal position and flipping it vertical yet again shuts down the stove

    1410900128-13.JPG


    The lever operates a sprung-loaded cam and rod that raises and lowers a cup, close-fitting on another cup, connected to the pick-up tube for the burner

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    The priming charge is pumped up that central tube, around the vapourising loop, back down to a loop at tank base level and up again ...

    1410901570-18.JPG


    ... through that tube below the burner with the silver metal sleeve visible on it ...

    1410901975-19.JPG


    ... which is the end of that pipe on the left supplying fuel to the wick gallery

    1410902000-20.JPG

    CONTINUES
     
    Last edited by a moderator: Jun 26, 2015
  2. shagratork

    shagratork United Kingdom Moderator Subscriber

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    John, that is a great acquisition.
    It is unusual and it looks so . . . . . 'cute' - OMG, did I say that?

    Four pints in eight minutes is amazing!

    Your photos show a very sophisticated and clever design.
    Shame that you can no longer get 'Pink' paraffin!

    Great photos, as always. :D
     
  3. presscall

    presscall United Kingdom Subscriber

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    Excess liquid fuel to prime the wick drains away back into the fuel tank from that open pipe visible in the burner base

    1410902362-21.JPG


    The wick gallery with the priming wick in place

    1410902533-22.JPG


    I'm supposing it's leaves of an asbestos material stapled together, but a modern stove door heat-proof tape would probably serve

    1410902546-23.JPG

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    The wick is easy to light when saturated with paraffin

    1410902566-25.JPG


    The 'concentric cones' chimney assembly is then lowered over the burner and the blue flame and intense red heat at the perforated dome appear as the thermo-syphon of vapourised fuel gets underway - quite quickly following the priming phase in fact

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    Some other details. The fuel tank and leg frame

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    Missing a sight glass and bezel, the fuel level indicator is a cork equipped with an aluminium sleeve, painted white on the top to be visible down the level tube

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    Enamelled stove chimney

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    I cited the trivet as cast iron earlier, but I'm thinking more 'sintered' from the gritty texture

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    Here on CCS it's a handle, on CPL it'd be a 'bail'

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    Lid here, 'hood' on CPL

    1410903244-40.JPG

    A BIT MORE YET TO FOLLOW
     
    Last edited by a moderator: Jun 26, 2015
  4. presscall

    presscall United Kingdom Subscriber

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    At centre top of the hood is a socket to slip in a lifting key in to avoid burnt fingers when swapping roles from stove to heater on a hot stove/heater. It'll be an easy job to make up something to suit

    1410903717-41.JPG


    Another socket appears in the centre of the perforated dome - handy using the same lifting key to pop the dome and concentric tube assembly over the priming flames

    1410903736-2.JPG


    Underneath the hood are wire supports to ensure the hood sits squarely and securely on the trivet

    1410903748-42.JPG

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    Another one for Newark, Trevor, or better still Gary (Redspeedster's) winter gathering up at Stanley if we're having another 'do'!

    Forgot to mention, the thermo-syphon gurgles in use - somewhat less intense than a coffee percolator at full belt, but noticeable and absolutely endearing - a homely sound I'd say.

    John
     
    Last edited by a moderator: Jun 26, 2015
  5. shagratork

    shagratork United Kingdom Moderator Subscriber

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    Ha! It will be a welcome addition to Gary's north-east meet.
    I missed this year's gathering but will not miss another.
    It is at a time of the year when it is always bloody freezing - so you heater/stove will be more than welcome!
     
  6. kerophile

    kerophile United Kingdom Subscriber

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    Hi John, what an interesting heating device, and the usual exemplary presentation.
    I can see how the very obvious "gritty" finish on the pan ring would provide a great non- slip finish. However, I doubt that it is a sintered product, and wonder whether it it has been deliberately cast in a coarse sand mould?
    This heater looks to be fairly "modern" perhaps even from the 1960s, when manufacturers were being encouraged to incorporate safety features to extinguish the flame if the heater was knocked over. I wonder whether the metal disc, or the concentric cups associated with the priming lever, could also be automatic shut-off devices?
    A great post!

    Best Regards,
    Kerophile.
     
  7. Stonehopper

    Stonehopper United Kingdom Subscriber

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    Excellent presentation as usual - looks a brilliant stove/heater.

    Want one!
     
  8. dusan Czech Republic

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    AUSTRIA EMAIL AG take over DITMAR 1939, so PHOEBUS WERKE AG 1959 too. WORK for enameled in WIEN is 1979 closed.

    Them my stove had name only DEMON.

    1410970568-Demon2.JPG

    1410970594-Demon1.JPG

    1410970620-Demon3.JPG
     
    Last edited by a moderator: Jun 26, 2015
  9. presscall

    presscall United Kingdom Subscriber

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    Interesting later example, Dusan, thanks for posting and for the company history snippet.

    Bit of luck, fuel level sight glass bezel turned up. Must have flipped off while in the car boot and I never noticed it was there in the first place.

    No glass though, but the retaining clip was in place in the bezel and I set about cutting out a disc of glass. A diamond-embedded cutting wheel in a Dremel scored the circle and a pair of pincers snapped the excess down to the line

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    Last edited by a moderator: Jun 26, 2015
  10. presscall

    presscall United Kingdom Subscriber

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    Turns out, the bloke I bought the Ditmar from had two, so I popped over and bought the other.

    It lacked a fuel gauge bezel, and I'd a bit of ponder on how to make a decent replacement, hitting upon the idea of usiing a Campingaz Rando gas cartridge base section, which killed two birds with one stone, since it answered a long-standing question on the interior construction of one of those gas carts HERE


    Here's the Rando gas cartridge partly dismantled. It's full of wadding to soak up liquefied butane and prevent flare when in use, since the Rando stove has the cartridge installed horizontally, which otherwise could result in liquefied gas getting to the burner when the cartridge is half, or more, full

    1411841723-a.JPG


    The bit I wanted for the Ditmar bezel was the base section, bottom left

    1411841741-e.JPG


    Here it is re-worked and glazed, the original Ditmar fuel gauge bezel on the right

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    Installed on the stove/heater

    1411841764-j.JPG

    1411841774-k.JPG

    John
     
    Last edited by a moderator: Jul 1, 2015
  11. presscall

    presscall United Kingdom Subscriber

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    I've come to really enjoy using the Ditmar.

    One last flame shot to round off the topic

    1411847504-1a.JPG

    John
     
    Last edited by a moderator: Jun 26, 2015
  12. kerry460

    kerry460 Australia Subscriber

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    lovely work John .
    using the bottom of the can is nice thinking or rather looking outside of the box for something that will fit and work .
    cheers,
    kerry
     
  13. presscall

    presscall United Kingdom Subscriber

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    Cheers Kerry.

    John
     
  14. Radler

    Radler Switzerland Subscriber

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    Hello presscal

    Great heather and presentation! I own one very similar to the one of dusan, but a bit older and a bit newer than yours. I like the peaceful little sound it makes under the table, it's something like a purring cat.

    I think your heather is too powerful. Boiling four pints (two litres) of water in 8 minutes seems very much to me for a unregulated heather, if you are not living in a tent. Have you tried to regulate this with the little pinion over the priming pump? Mine consumes 115 to 135 g of kerosene per hour, more would be incommodious to me.

    BTW. window glass can be cut round with ordinary scissors, if you do it under water. It's a surprising physical trick. But don't use your best dressmaking scissors!

    Best Regards
    Radler
     
    Last edited: Mar 5, 2016
  15. presscall

    presscall United Kingdom Subscriber

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    Hello @Radler

    That's a great analogy, "... Like a purring cat." It's true, it does sound something like that.

    Regarding the level of heat output, it's powerful but comfotable in a room. Still, it's an unregulated burner and it would be useful to control the output. With no user instructions, I wasn't aware that that 'pinion' had an effect. Having heard from you that it does I'm trying to work out how it affects the output. What would you suggest, lower the priming piston to reduce the fuel supply and output?

    Thanks Radler.

    John
     
  16. Radler

    Radler Switzerland Subscriber

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    I am not sure and still on search for a hidden feedback mechanism between room temperature and heath output.

    My first attempt was to have the stove outdoors at 3°C before starting it indoors. The test gave no well visible difference in the output. The temperature of the kerosene in the tank has an influence on the cooling time in the lower loop and how much vaporized gas condenses, but the effect is not enough to regulate the stove.

    The mentioned pinion could regulate a spring load on the inlet-valve, but I have not opened this part yet, because I am handicapped with my eyesight at the moment. I think the pinion is a possibility to fix the general power level of the heather. But I have the idea there could be a hidden automatic regulator with feedback of room temperature. A possibility could be a rod of a metal somewhere with high thermic expansion. But this is speculation. The basic experiment, to operate the heather outdoors and measure and compare the consumption of fuel, I have not made yet.

    Another question is, what happens, if the heather is overthrown. I think, the fuel supply would stop as soon as the wick is dry and the upper pipe loop cools down. An experimental proof of this theory would be interesting.

    For sure, this heathers are very well engineered and worth studying.

    Radler
     
    Last edited: Mar 5, 2016
  17. presscall

    presscall United Kingdom Subscriber

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    A thoughtful and thought-provoking reply which I've come to admire in the content of your posts @Radler.

    I'm not inclined to try that 'topple test' but it's inconceivable that such a sophisticated design wouldn't incorporate a safety shut-down arrangement in such an event.

    I may try adjusting that screw fitting as you've suggested however.

    Thank you.

    John
     
  18. shagratork

    shagratork United Kingdom Moderator Subscriber

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    Cutting widow glass under water with scissors!
    I have certainly never heard of that. Must give it a try sometime.
     
  19. Rickybob United Kingdom

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    outstanding! thermo-syphons?? i need to go and lie down
     
  20. Wim

    Wim Belgium Subscriber

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    Hi John @presscall , what you need to lift the hood and dome looks like this; made out of a strip 1cm wide, 1.5mm thickness.

    Can't sell you this one, bought it yesterday for €25!

    P3130037.JPG P3130038.JPG
     
    Last edited: Mar 13, 2016

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