Question on building my propane melting pot, should I vent ring on bottom?

[bzajdek]

Before I weld the ring to the bottom of the pot should I drill or cut vent holes to get better flame or heat to the bottom of the pot?

[William Yanda]

Good question. Your burner will draw air from behind the orifice, but making the flow of exhaust easier can't hurt, in my opinion.

[1_Ogre]

I'm not sure if vent holes will provide any benefit. The bottom of the pot will get even heat distribution either way

[bzajdek]

Ok, so with the replies as of now it does not seem necessary, nor would it provide any benefit. I was just trying to get opinions before welding the ring as it would be much easier to perform the cut outs beforehand. I was not sure if the closed space would make the burner run worse or dirty. I will be using a bayou double jet burner to melt range scrap, and wheel weights this spring and make different alloys with linotype in the fall after the hot summer weather is over.

[country gent]

I used a 1 1/2" hole saw and cut 8 ( every 45*) half holes around top edge of the ring to allow for better heat flow and venting. It does seem to help with keeping the flames on the pot all the way around and up the sides. I can have 130lbs molten and ready to cast in 20 mins with my burner.

[bzajdek]

I used a 1 1/2" hole saw and cut 8 ( every 45*) half holes around top edge of the ring to allow for better heat flow and venting. It does seem to help with keeping the flames on the pot all the way around and up the sides. I can have 130lbs molten and ready to cast in 20 mins with my burner.

I was thinking holes may help with heat distribution but I was worried too much may lose some heat. I am not sure how much though? I also thought the flame might burn cleaner and deposit less carbon to the bottom of the tank if some flame could heat out to and over the edge of the ring.

[bigted]

Def put holes in the top of the ring ... Closest to the weld edge. Id make em 1/2 to 3/4 inch and space them every 2 inch around the circumference. Also i would drill these holes as close to the edge as i could get them and leave just a 1/4 to 3/8 inch metal.

Your concern is justified as the dead end will fill with hot air and then the remaining useable heat will drop back down and cause a lack of oxegen to the burner which will make your flame way les efficient thus wasting good propane.

[jsizemore]

I'm with country gents design. A solid ring will cause the heat to hit the pot bottom and then be deflected away from the sides. The heat up the sides is fairly important in the winter if you melt 100+ lbs of lead each time. Soot buildup is a burner performance problem and not caused by the pot. Ask the folks that work on gas packs and gas water heaters. Wind screen and lid will help with gas efficiency.

[lwknight]

I tend to agree with jsizemore on this. Now as to just how much venting would be optimal is going to be trial and error.
It does seem that he HP burner design would require venting to carry more heat up the sides.

[country gent]

I think if I did another one I would use a 1" or 3/4" hole saw and every 22* around the out side edge. Well Id set dividers to give 16 evenly space spots and call it good. This would allow for more even venting around pot and a slightly better flow. But my big pot works real good now with 130 lbs or so of lead in it. I put the ring around mine for a bigger foot print to set on and be more stable the cuts were secondary for me. I used a starret hole saw to cut them with a hand drill motor. This was easier for me than a drill or end mill was. If making more than one lay out and drill holes then split rings on center line of the vent holes and you get 2 rings for one set of holes.

[Dragonheart]

I allowed for some venting around the skirt of my pot and it works well.

[dead dog]

How far should the burner be from the bottom of the pot?

[country gent]

Distance from pot will be dependant on several things. The amount of air needed for the burner ( a cooker burner uses less oxygen than a weed burner type burner) the amount of shielding around your pot and burner. I recently dropped my weed burner down an 1 1/2" more from the pots bottom and to a point almost even with the heat shield. Doing better now and I might go another 1" yet to make it easier to light. A big burner up high in the shield can burn of oxygen faster than it can be replaced

[mold maker]

Keeping the heat against the pot is more important than BTUs. An efficient windshield that contains the heat is much more effective. The bottom of the pot gets all the heat first, but allowing the heat up the sides of the pot makes much better use of the fuel.
My burner is contained inside a metal 5 gal bucket (windshield) with a 7" hole in the bottom for air. The pot sits 2.5" above the burner and has about a 1/2" space around the top. All the heat is contained within the shield and against the pot.
This made it lots more comfortable to sit next to, and I no longer run the burner full blast. This cut the melt time and saved on gas.