DIY Flame Weeder?

Anyone ever make or see a simple wide DIY Flame Weeder? Most designs I see are just single burners connected to a frame in a line, but presumably you could drill holes down the length of pipe, install a wind shielding skirt/burn chamber/air mix chamber with some air holes on the top???

Looking at the single burner designs it looks like the top holes are almost half the size of the bottom exhaust holes, and the skirt is probably about 5 inches. The biggest issue I see is getting the right air/fuel mixture in the burn chamber.

I am seeing some people make heating/cooking style burners with a pipe with hole drilled in it, but that uses a pre mixer, with the air mixing in the pipe on the way to the holes.

It would be helpful to know some details of the problem you are trying to solve. Is a flame weeder the best solution? Is there a different approach that might work?

Flame weeders burn a ton of energy. You may have noticed that propane isn't cheap any more.

I have some concerns about homemade propane appliances. It's possible, but tricky. Would a tiger torch with a homemade diffuser do the job more safely?

And pardon me for being silly -- but I have this image of a free propane BBQ off Kijiji, inverted and mounted on metal skis, being dragged through a weed field. It already has all the parts in place ...

I have seen guys build multi burner forges for smithing swords. Those should work.

Hello Douglas Aplenstock,

I think it is the best solution for organically weeding carrot beds prior to the carrots breaching the soil.

I already have something like included pic, which seems to be the same thing as a tiger torch, but want something that would do that over a 3 foot line.

As you said, I agree I think the “biggest issue I see is getting the right air/fuel mixture in the burn chamber”.  

On the issue of needing propane, for a long time I’ve thought about using a simple woodstove, even just a rocket stove, with an electric blower to direct the heat down. Never got around to making one but it seems like it would work.

I use one for weeding, $25 from harbor freight. Well worth the cost since it has an integrated igniter, trigger, and adjustment valve, and handle. All of which are necessary, IMO, because you want to be able to control how much gas you're putting out. Too much torch and it deprives itself of oxygen and dies. I'm all for DIY builds but for the cost of materials, pre-built is more cost effective in this case.

Just my $0.02, this is an area where I'd buy rather than build. Hard to get all the pieces and materials in place for less than the cost of a prebuilt unit.

Is a flame weeder organic?  It doesn't leave a chemical residue?  So I guess it's considered organic, but it uses propane, so maybe it skirts the edge.  I live in CA, where everything is so dry, that just the thought of them scare the *✓π÷§∆ out of me.  At least it's not Roundup.  Be safe, and let us know how it goes.

Hello all, After a lot of research and messing about I finished my weeder.

To answer some of the concerns and questions, lets first start off with the reason the why.

Safety: The standard multi burner flame weeder I went with mixes the flammable gas in the ignition chamber, instead of through a hole upstream in the pipe. This was a no brainier for me, I did not want to be messing with the fluid dynamics of explosive gases or dragging a burner though a muddy field when it had holes in the system not inside the burn chamber. This design is literally impossible to screw up, the entire system only has holes where it is allowed and supposed to be on fire.

Cost: A single burner unit in Canada is about $80, a multi burner unit is about $800. This cost me $20 in materials to build.

Why flame weeding: We already use a single burner flame weeder, it works great for the few things that we use it for but is slow. It is a traditional organic method. People even use it directly on their food (BBQs). Maybe it is bad for you, I am no expert. Also, here in Ontario you could not get a flame to spread if you wanted to. Really it was never my decision to  do any flame weeding, I just saw people using a slow method of flame weeding and losing out of some beds because of this slow speed so decided to make it easier.

Design: The single burner unit I had came with a 18 PSI regulator rated for a maximum of 500k BTU of throughput. The Burner wand was rated at 100k, so I could use 5 of them (which is the standard multi burner design). The unit ran off a 1/4" pipe, had a 3/64" fuel nozzle, a 2" X 5" pipe burn chamber guard pinched on one end to connect to the pipe leaving two air intake openings. The unit already was capable of connecting to standard 1/4" pipe thread so it was easy to just copy this setup exactly. The one thing I changed was it had a on/off valve near the burner end of the contraption that used a tiny hole for throughput, I left this off to maintain as much flow as possible.

Thank you for sharing your DIY build.

I like DIY projects because when I do one I feel like I have accomplished something.  I bet you did, too.

Jon Wisnoski wrote:Hello all, After a lot of research and messing about I finished my weeder.

Cool! You seem to have thought it through very thoroughly.

Can you upload a pic or two?

Way to go Jon.  I could see my boys doing something like this.  Not only because it's often much cheaper, but because they can. They often think they have a better design. Sometimes they do, and sometimes it doesn't work out. Be creative is it's own reward.  I hope it saves you lots of time.  Thanks for sharing.

Sorry it took so long. Here are some pictures.

How I would do this differently next time:
Flip the design! I would rotate the frame so the burners are on the end and the whole thing works as a teeter totter so I could control the burner height.

Simplify! Pretty sure I did not need all those fittings and pipe threading work (you should just need a single fitting). Once the gas is connected with a single fitting to straight pipe, just drill the nozzles in the side of the pipe, welding the 2x5 burns chambers directly over top I think it would of worked just as well and been almost no work and far cheaper. To explain it another way Have a single straight pipe connected to the propain. Drill nozzles approximately every 7.25"; Center the holes in 2" diameter pipes (cut 5" long); Weld in place.