I converted a Butterfly lantern for winter heat drum duty. I was never satisfied with how the darn thing ran and the conversion kept it from being a shelf queen. With the weather turning cold I decided to run it to take the chill off the side porch while I was doing some work. With good pressure it kept running lower and lower. Activating the cleaning needle helped momentarily but stepping into the house for a moment gave it time to fizzle out. A damp spot of kerosene beneath it as insult to injury. I've never been able to keep this preston loop vaporizer running clean. K1 water clean fuel shouldn't be an issue. So I go grab my Colemen 228h kerosene conversion and runs without issue. This has been sitting a while but hardly has any run time on it.
I'd say the reason its running not as well as you would like as a heater is because the heater cylinder is shrouding/shielding too much of the heat required to keep to Preston loop hot enough for better vaporization of the fuel. You could try one with a more opened meshing, (preferably in direct contact with the generator) so that it glow red-hot when being impinged with the flame from the burner.
Opening up a few holes has crossed my mind. When it does run only the top half of the drum cherry's up. My understanding of the preston loop is that the halo acts as the heat sink, heat rises and Bob's your uncle... I'll clean out the vaporizer this weekend and open a few holes on the side towards the vaporizer tube. I'm apprehensive about getting crazy on this but may open a few along the lower edges as well to promote flow down the length of the heat drum. Anyone with an original? What size hole??
I've never seen a Butterfly as a heater before @anlrolfe . But you could always roll up one from some stainless steel or nichrome wire mesh to test out first before altering that heat drum. After you clean up the Preston loop and other parts, just assemble without the heat drum and light up to check if the flame's a nice uniform blue without the yellow-orange tinge. That's just to ensure it won't soot up the heat drum in any way. To promote the flame reaching the lower part, you'll need to make that portion more opened so that some of the flame and exhaust products would be able to vent towards that direction and not get repelled away upwards or sideways. Or you could close up some holes in the upper section a bit. From the appearance of the heater drum, I'd guess its impeding the flow of the 'flame' and combustion products a tad bit too much. My suggestion is to try a heat drum with an 'openess' similar to a mantle. It should glow bright or cherry red throughout.
The lamp is not running in this photo. It sits here stone cold. The heat drum and deflector plate were obtained via BriteLyt Heat Shield & Heat Adapter Heat Shield with BriteLyt Heating Adaptor-part#HPBHA – Britelyt Anticipating thermal issues I wrapped the base of the generator with several turns of copper wire. Do original heat drums have holes in the bottom or just the sides. Concerned about reflecting too much heat towards tank.
These heater drums are designed for 500cp Pmax lanterns (and clones). If your Butterfly is a 350cp one there will not be enough heat produced to keep the system working. Making a "bulb" out of stainless mesh as mentioned above is a good idea I think. To make the whole heater more efficient a reflector is a good idea, one can be made from an empty tin (I have 3liter olive oil tins that are bright on the inside (plated?), these can be easily "wrapped" round 3 of the 4 posts (bars) that hold the top. No need to use the globe, as it also stops some of the heat. The reflector replaces the globe more or less and as heaters are used 'indoors' there is not much wind plus the heater does not get easily damaged unlike the silk bulbs. Best regards, Wim @anlrolfe
@anlrolfe Personally, I don't think it's anything to do with the heat drum. Did you use the lantern with a mantle before converting it to a heater ? How did it perform ? It is well known that even when brand new, these Asian made clones usually require "adjusting / fine tuning" before they work at optimum efficiency. This may well be the case and if it is, simply swap out the jet and cleaning needle for 500c.p. but before you order parts, allow me to experiment with different jet sizes in my Petromax version. Henry.
@anlrolfe Things you can check before throwing money at your lantern. Cleaning needle: a) they can work loose and yes, a loose needle can affect operation. Is it tight ? b) needle should protrude between 0.5 and 1mm when raised. Any higher than 1mm and it may restrict vapour flow when fully down. Air gap: Check with needle down. 14 to 14.5 mm between top of jet (gas tip) and bottom of mixing tube. This setting for both 350 and 500 c.p. lanterns. Mixture control: The paddle in the mixing tube is in line with the screw slot. Check that it is vertical. Henry.
Simple solution is to remove the heat drum and run it as a lantern. The heat drum may give more radiated heat but it will not give more than the standard Mantle of the lantern will. A 350cp lantern gives out about 1.25KW heat anyway and you can't increase that at all no matter what you fit as a mantle or a heater drum. ::Neil::
But the OP says he was never happy with it as a lantern which is why he fitted the heater conversion. If it's not working correctly with either a mantle or heater drum, it seems to me that the fault is with the lantern, not the accessories, hence the suggestions in my previous post. Anyway, here are some images of my Petromax 1500 with heat drum. The first image is as it should be with a 500 cp jet fitted. With 350 cp jet. And just for fun, 250 cp jet and air gap adjusted accordingly. After each change of jet, the lamp was allowed to run for 5 minutes with the pressure gauge needle on the red line before taking a picture. Henry.
The issue was that the mantle corona would over fill the mantle. I went to a larger CP sock which mostly corrected the issue but it would also pulsate IIRC. I can get nice even light out of all my other lanterns so, try heat drum.
@Henry Plews That's an awesome specimen and great example of power output resulting from jet size. I think I've got some cleaning in order. Something has got to be gumming up the works.
@anlrolfe I hope that cleaning and adjusting as necessary, will improve the burn. If it still pulsates, rolling some fine brass mesh around the needle rod could help stabilise the flame. Henry.
Nothing significant found during the cleaning. I did have a piece of brass wire mesh in the top on the vaporizer. I cut about 1/2 turn off the circumference to get it lower into the tube. It's about 2cm long and extends from the upper part of the Preston loop down. I drilled 1 vertical line of holes larger lining up with the vaporizer. Firing it up I had to keep pumping to maintain pressure. I think the preheater is leaking air. Nibs are very particular sometimes. When I went to fuel it up before lighting my jug of fuel had some floaters in it, so perhaps several issues. Thanks for the input guys
Yes, much better. There was some carbon fouling in the base of the jet but the rest of the vaporizer was just fine. I do think the few larger holes down the side has aided with allowing the volume of the flame to fill the canister(heat drum). Beforehand much of the jet was repulsed back on itself. I believe that my caution and restraint with the drill is justified but venting towards the vaporizer is warranted.
That's good news. If you suspect a slow air leak somewhere, sealing that up would make it work even more satisfactorily. You can always experiment with different heater shapes and configurations to get the best results. The loop of the generator should receive a good amount of heat, some directly from the flame and also by being in as close proximity as possible to the heater cylinder. Some internal carbonization in the jet is normal for kerosene but not external sooting. If you are getting some soot on the outside, it means the fuel-air mix is a bit too rich. If the flame is perfectly blue, that indicates good fuel-air ratio. This wouldn't soot the internal surface of the heater. If its slightly yellow, the sooting will be there, which would eventually reduce the heating efficiency.
