This burner is a variation of the burner described by Ron Reil in:
The propane (or natural gas) is sprayed through a small orifice down the throat of a 3/4" pipe. A reducing bell acts as both a place to mount the orifice and as an air scoop. The end of the 3/4" pipe is given a flared nozzle to reduce the air velocity to less than the flame velocity to retain the flame.
Ron's original version holds the flared nozzle on with three setscrews and holds the propane feed to the reducer mouth with saddle clamps and four more screws. A variation by Bordeaux eliminates the saddle clamps and two of the four tapped holes by drilling a large hole through the reducer near the big end and holding the feed tube in that hole with two screws. A modification that Ron calls "EZ-Burner" replaces the flared nozzle with a step nozzle made of 1" pipe and held in place by using tapered pipe threads as a clamp. That change eliminated three more tapped holes. The first burner I made was made with the EZ-Burner and Bordeaux modifications. It took about 2 hours to build after purchasing the parts at the local hardware store.
I added my own variation to eliminate the remaining two tapped holes: Rather than drilling through the reducer and drilling and tapping holes for setscrews, I thread a short piece of 1-1/2" pipe into the large end of the reducer and drill through the pipe. Tightening the pipe into the reducer will then clamp the propane feed tube in place.
|1||1/4"||Hose Barb Adapter|
|1||2"-3"||1-1/2"||Pipe, Threaded One End|
|1||1-1/2" to 3/4"||Reducer Coupling|
|1||6"-12"||3/4"||Black Iron Pipe, Threaded One End|
|1||1"||Black Iron Pipe Coupler|
|1||3"-5"||1"||Black Iron Pipe, Threaded One End|
|2||1/4"||Hose Barb Adapter|
|1||4"-6"||1-1/2"||Pipe Nipple (Cut in half)|
|2||1-1/2" to 3/4"||Reducer Coupling|
|1||12"-24"||3/4"||Black Iron Pipe Nipple (Cut in half)|
|1||1"||Black Iron Pipe Coupler (Cut in half)|
|1||6"-10"||1"||Black Iron Pipe Nipple (Cut in half)|
|Nominal Drill Size||Decimal Inches|
The tools you are least likely to have on hand are the drill bit to make the gas orifice and the 9/16" drill bit. Be sure to get a 9/16" bit with a shank small enough for the chuck of your power drill.
The burner is now complete.
The ideal method is to use a gas pressure regulator designed for low pressures (about 0 to 10 or 20 PSI). For small-scale heating you can use the valve from a propane torch and use 14-ounce propane canisters. For most purposes you will want to use a 20-pound (or larger) propane tank. The valve on a 20-pound tank is designed for On-Off and not for fine control. You will want some sort of control valve and, ideally, some sort of adjustable pressure regulator.