Optimus 702 radiant heater

Discussion in 'Heaters' started by Carlsson, Nov 9, 2010.

  1. Carlsson

    Carlsson Sweden Admin/Founder Member

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    I assume that this one should have the designation 'F' for nickelplated tank and reflector, but I haven't seen it in catalogues like in the cases with the 700F and 703F, so I left it out in the subject for now.
    It uses a tank that is of the same size and appearence as the one used on the 300-lantern, just not with the 300-text anywhere.

    1289337317-702_fram.jpg

    1289337317-702_fram.jpg 1289337323-702_bak.jpg 1289337330-702_tank.jpg
     
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  2. Nils Stephenson

    Nils Stephenson Founder Member

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    I don't see a pressure release on the filler cap. I wonder if this heater came originally with a regulating burner so it could be turned off while keeping pressure in the tank? I havn't seen it in any catalogue, but that would most likely make it a 7702.
     
  3. Carlsson

    Carlsson Sweden Admin/Founder Member

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    Nils, it actually has the pressure release valve. Hard to spot on the pics, though.
    Below is a picture of this radiators valve assembly. Can be a good illustration to show what we are talking about, and the exact function.
    Funny about the wings on this lid. These are rectangular, while the other two Optimus radiator I posted has rounded wings on their lids.

    1289418351-srv.jpg
     
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  4. Nils Stephenson

    Nils Stephenson Founder Member

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    These square winged type filler caps are from the last period with the type of logo on this tank. That means it should be from the late 30s or early 40s. What I was wondering about was why it doesn't have the normal 'manual' pressure release screw like on a lamp? To turn it off as it is you have to loosen the whole filling cap.

    The rounded type filler on the two other heaters are of the type used on stoves from the 30s. Both use stove type tanks so this is apropriate for them.
     
  5. Carlsson

    Carlsson Sweden Admin/Founder Member

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    Ah. Sorry for misunderstanding you.

    Maybe the 702 never had an air release. The lamps I've seen with this tank has the air release screw directly in the lid itself, rather than on the socket. In that case, I guess the normal thing would have been to have that kind of lid on this one.
    As you say, It really should have an air vent for distinguishing the radiator.
    I think it should have this even if it was a 7702. Somehow I feel that it's not a normal construction for a Swedish paraffin apparatus to let the pressure remain when it's not being used.
     
  6. Nils Stephenson

    Nils Stephenson Founder Member

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    Actually I can't find any reference to the 702 in any of the catalogues I have copies of. Mostly the heater section is missing from what I have. Looks like we will have to look for more heaters to see what is out there.

    Here are a couple of pictures I have found of others. The first is Bo's, I hope he doesn't mind me showing it here. It has the first style of filler cap and it looks like it is blocked like yours. That's the biggest picture I have, so I can't zoom in.
    1289464274-1686.jpg

    Next is a picture I took of a heater that is hiding in the back of a shop in Copenhagen. It is in for repair, but has been there for years. Every time I see the owner I try and get hold of it. No luck yet. As you can see it has the next style of filler cap (the one before yours) and is the normal configuration with pressure release.
    1289464473-Optimus_702_tank.jpg
     
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  7. Mackburner

    Mackburner United Kingdom Founder Member Subscriber

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    That is a pressure relief valve not a release. An automatic device to limit pressure in the tank. Odd thing to waste money on really as the pump tube design limits pressure anyway to about 1.75bar ::Neil::
     
  8. spiritburner

    spiritburner Admin

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    In the 1939 catalaogue - the 702 is shown with a regular pressure release on top if the cap. In the parts listing this is also shown. On the same page is the 703. The picture shows a pressure release but the parts show a safety release, like Christers & a conventional filling collar with side pressure release.

    The '34 &'36 catalogues shows both with the pressure release on the cap in illustration & parts listing.

    So it looks like the 703 cap changed but not the 702. Maybe a previous owner replaced the cap with the wrong one?
     
  9. Carlsson

    Carlsson Sweden Admin/Founder Member

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    Very possible, Ross.
    The lids are one of the parts that you never can be sure about since they are so easily swapped.

    Yes, just as we have said in the posts above. :lol:
    But I do agree that I don't see much reason for them. Perhaps it's mainly a gimmick, or perhaps they are afraid that the tanks should be exposed to an outer heating source. Wood stoves, fire places etc.
     
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  10. Nils Stephenson

    Nils Stephenson Founder Member

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    I wouldn't rule out the filler cap being original. It just seems odd though. It also looks like Bo's has a pressure relief type filler cap, so maybe it is right. If I remember correctly, there are Optimus stoves that don't have a pressure release when using a regulating burner. Maybe it's the burner that's been replaced here and not the filling cap.
     
  11. Carlsson

    Carlsson Sweden Admin/Founder Member

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    Also a possibility. That would apply to Bo's radiator too then.
    When the burner needed to be replaced, they could just as well have gone for this unregulated one, and I guess it also would be the cheapest alternative when the replacement became necessary.

    I assume that the regulated burner also has a built-in pricker?
    If so, I really would prefer one of those. I often need to clean the jet on the 703 (which is the one I use frequently).
    Guess a good cleaning of the tank and a decoking of the burner is called for. :doh:
     
  12. Nils Stephenson

    Nils Stephenson Founder Member

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    It's just the 'standard' regulating burner with cleaner found on lots of Optimus stoves and Radius as well. It was actually Radius that patented the burner in 1931 (SE79784). If you put a regulating burner on the 703 it would then be a 7703.

    You could also just clean it as you say. A clean tank and burner shouldn't need pricking at all.
     
  13. Gerard

    Gerard Netherlands Subscriber

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    Another filler cap from a 703F :). With a pressure relief valve too. How many combinations are there:?:.

    Greetings,
    Gerard


    P1040610.JPG
     
  14. Carlsson

    Carlsson Sweden Admin/Founder Member

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    Maybe you should have posted this with the other 703F seen here?
    It's the same kind.
     
  15. KAB

    KAB Subscriber

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    A nice example, my 700F, stove tank ( see gallery) needs the drilled dome to sit on its burners to complete.

    Light and enjoy
     
  16. Gerard

    Gerard Netherlands Subscriber

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    I realy should have :oops:
     

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