I was looking at your pictures and i didn't notice any smoke bypass. Almost all of these downdraft style boilers have a trap door smoke bypass in the top of the firebox for getting the fire started. How are you going to start the fire?? It looks like your welding is with a 110 volt wirefeed. You must be really pushing that welder, welding 1/4" steel? I see some of the welds are flux core wire. How much water do you think it will hold? What thickness are your 4" pipes? Keep up the good work!
Nope no smoke bypass I'm just let it roll out the front door I thought about adding one but I feel like I'm in deep now with the build and after watching some videos you load the wood in stuff some news paper in light it off close the door and turn on the blower and 5 Min later you got a fire.
I'm using a 110V 100Amp Lincoln weldpack running .035 and 75/25 gas the duty cycle is 20% and is a build killer you just need to plan what your doing weld until the cutout hits and then cut metal prep your next weld cleanup ect until you hear the cutout click back in and go back to welding.
The 1/4 firebox was welded with a Lincoln AC225 stick welder the MIG will weld 1/4 but it takes multiple passes and is slow but is very clean so i only used it on small parts doors latches and all of the 10awg water jacket parts. The AC 225 is also only a 20% welder just weld until it stinks and wait.
Pipes are 1/4" sch 40
I've filled it already to chase leaks and it holds 316 gallons.
Thanks for the complement going back to work on it.