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Thread: As promised—How I light a Hot Shot waste oil burner

  1. #21
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    Quote Originally Posted by Tobho Mott View Post
    Not trying to be contrary, but in the video and write-up in post 1 it seems pretty clear he is using his hot shot to preheat with propane and a turned-down bucket vac, without any trouble, then once it is hot, he is gradually adding oil and more air while backing off the gas until he is running on pure oil.

    I am already using low propane pressure and a hair dryer w/ dimmer switch to preheat, it's just that it keeps blowing out and it is inconvenient to switch blowers and fuels at the same time. I haven't played with the propane side of my burner too much, but it will not burn using my scavenged BBQ regulator even with the vac turned down as much as I can turn it, or with the hair dryer turned up more than maybe 2/3 of the way. My burner is very similar to a hot shot, so the main difference seems to be the regulator from what I can tell. Unless there is maybe a problem with where I plumbed the propane line into my burner. (Pictures of it here: http://www.alloyavenue.com/vb/showth...l=1#post180724 Too close to straight across from the blower?). What I want to do is to narrow it down to just one blower that both fuels can handle, simple, like in Rasper's video.

    Jeff
    where is the outlet of the propane line in your burner?

  2. #22
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    For some odd reason I can't reach page two of this thread to review everything before replying so bear with me if I'm off track.

    Jeff... I also initially had a problem with propane blow out with my brute style burner as well. I have only ever used a bouncy castle blower and use a high pressure regulator. My fix was a spin vane (turbulator) at the mouth of the burner. You need to slow down your air speed, and a spin vane does exactly that. I'm won't bother arguing the merits of a spin vane or lack there of. It just has enough upside for me to use one.

    Oh... after some time playing, I also discovered that I have an easy time lighting/using my propane preheat naturally aspirated. So when I'm warming things up I leave my blower off and allow the burner to pull whatever air it needs by itself. When things start to warm, I crank the propane, turn on the blower fully choked (even choked it still makes a notable difference) until I switch to oil.

  3. #23
    Senior Member Tobho Mott's Avatar
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    Quote Originally Posted by dallen View Post
    where is the outlet of the propane line in your burner?
    It's the line with the brass parts here; it just feeds straight into the tee, there are no parts inside the burner that can't be seen here other than the oil tube.



    You can see here about how far in the front end of the burner was. Too far back?



    So the possible issues seem to be:
    1) bbq-regulated propane pressure too low (Rasper agrees, I think Masteryoda disagrees.)
    2) bucket shop vac too big for propane, period (Rasper's video eliminates this as a possibility IMO)
    3) need a turbulator (Yoda and J. Vibert suggest this, I do not think Rasper uses one)
    4) placement of propane line in burner (hoping for feedback from dallen or anyone else)
    5) position of burner in furnace (hoping for feedback)
    6) some combination of the above

    Thanks to all of you for all the feedback and advice!

    Quote Originally Posted by J. Vibert View Post
    For some odd reason I can't reach page two of this thread to review everything before replying so bear with me if I'm off track.

    Jeff... I also initially had a problem with propane blow out with my brute style burner as well. I have only ever used a bouncy castle blower and use a high pressure regulator. My fix was a spin vane (turbulator) at the mouth of the burner. You need to slow down your air speed, and a spin vane does exactly that. I'm won't bother arguing the merits of a spin vane or lack there of. It just has enough upside for me to use one.

    Oh... after some time playing, I also discovered that I have an easy time lighting/using my propane preheat naturally aspirated. So when I'm warming things up I leave my blower off and allow the burner to pull whatever air it needs by itself. When things start to warm, I crank the propane, turn on the blower fully choked (even choked it still makes a notable difference) until I switch to oil.
    Since I was using a dimmer switch to control shop vac, it did not occur to me to also choke the vac's intake. I bet that would have made it possible to slow the vac down enough to avoid the blower swap, though perhaps it would not have helped much in stabilizing the propane burn once it actually was lit. I also haven't tried seeing if it will run atmospheric when it is in the furnace; that is an interesting possibility, thanks again!

    Jeff

  4. #24
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    looking at the photo of the burner in the other thread I would hazard a guess that the burner tube isn't long enough for the air and gas to mix properly, you burner tube looks to be pretty small in diameter you may want to step up from the tee to the next size larger pipe which will give you some more room,

    its all in the ratio's of air to gas plus the length of the burner tube

  5. #25
    Senior Member Tobho Mott's Avatar
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    Thanks.

    If my 1" tube is too narrow, that is a little disappointing since the Moya design calls for a 1" tube and that is why I bought this one. But it would not be so hard to install a bigger one, so that is a plus. Also disappointing if it is too short - I made it by cutting a 24" long nipple in half, so the other half is just as much too short as this one.

    In any case, it seems I have a trip to Candian Tire in my near future, so at least it's not a total loss.

    Jeff

  6. #26
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    try this, get a rag or something that you can soak with oil and set it on fire in the furnace, with the burner setup like your going to melt metal, then turn on the air at a slow speed, then start turning on the gas slowly until it lights. you should reach some point where it will light and burn like its suppose to.

    video's are very helpful when trying to trouble shoot problems like this

  7. #27
    Senior Member Tobho Mott's Avatar
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    That is pretty much how I lit it when I fired my refractory this past weekend, though I just used some non-soaked burning paper, then later on I used a burning stick. I could always light it (using a hair dryer with a dimmer), it's just when I tried to turn anything up at all or use the shop vac and dimmer that it would blow out almost every time. I will try and shoot some video soon. Thanks again!
    Jeff

  8. #28
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    that sounds like its not getting enough LP

  9. #29
    I went back and read the whole thread and watched the vids. there are a couple of things that are being missed i think.

    Regulators are a valve that is opened or closed based on the pressure difference across a diaphragm one side of the diaphragm has the gas pressure the other side has atmospheric or a reference pressure + a spring pressure the difference between high and low press regulators is the spring pressure.

    Low pressure and high pressure propane burners are 2 completely different operating burners.

    The high pressure burners are either using the high pressure propane to aspirate the combustion air through a venturi such as Riel burner. or they are being used in a small bore high combustion pressure burner. This is the design both of Rasper's burner and Tobho Mott's burner using a vacuum cleaner as a combustion fan. When a high pressure combustion fan is being used the back pressure pushes against the regulator and reduces or completely stops the flow of LP. These type of burners would require a regulator that provides a higher pressure than the combustion fan is providing.

    Low pressure burners must deliver the propane into an atmospheric pressure burner in order to get flow. that is why the burners need to be fairly large as well as the orificing is fairly large compared to high pressure orifices. The combustion fans are High flow Low pressure fans or if using a vacumm cleaner, or leaf blower they would need to have the supply side closed down as those fans are designed to work against a supply pressure. When i use a leaf blower or vacuum i feed the burners through a PVC ball valve in order to control the burner velocity and pressure. A bounce house blower or dust collector blower is absolute max for pressure and would need discharge damper control for low pressure burners. For a curcible furnace for non ferrous work a hair dryer is sufficient air for up to about 125kbktuh or 3/4 gph oil equivalent even a hair dryer puts out to much air if your firing less than the 125kbtuh. I use a washer with a 3/4 to 7/8 hole at the outlet of the hair dryer on my smaller burners.

    Blow out is caused by one of 2 things either the velocity is to high which is handled by a flare, or tabulator/baffle or to lean a fuel mixture.


    I hope this helps some

    Art b

  10. #30
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    I just pipe my propane into the side of the Hot Shot and Brute burners as in Dave Allen's photographs.

    Why make the oil burner so short? Mine are at least 2 feet long.

    You want a lot of heat to pre heat your furnace. I watch the crucible. When it is red hot I know I can begin to turn on the oil. That takes less than five minutes for me. As an added advantage, if for some reason the oil flow stops, I can turn on the propane and get the same amount of heat—almost. I had to do this once when I had water in the oil tank from the rain.

    Richard
    When I die, Heaven can wait—I want to go to McMaster-Carr.

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