I've been using home made kiln (omega PID + SSR + nichrome wire + some refractory bricks) to heat treat A2 and similar for some time now and it all works great.
I am thinking about moving up - expanding the internal volume somewhat and that will require going 240V (I want to be able to reach reqd temps in minutes and with my 9x4x4 cavity 110V @ 15A barely makes it).
I will keep most of electronics - only replace the spiral to longer one. About wiring - do I get it hooked up between 2 hot legs of 240 ( in series with SSR of course) ? I will use the ground to ground the oven . Otherwise I'd need to use 2 spirals in parallel (hots to neutral) and doing that will require 2 SSRs (what pros/cons of these 2 methods ?). Was thinking about getting an electrician to give me a dedicated 240V in garage, with 20A breaker .
And about argon: for now I use tool wrap steel and it works OK, but I do get some scaling and softer decarb in the outer layer - which I grind off. Even using the paper-in-the-foil-bag trick. Assuming I have a top-load oven and it's rather air tight below the lid, can I simply flood the interior with 2-3 CF of argon before starting the heat treat cycle ? Being heavier than air , will it stay "put" inside of the oven - even when heated up to 1800F-2000F ?
I know some people keep moving inert gas through the oven throughout the cycle (at slower rate), might need to do the same. Drill a smallish hole through firebrick, stick some time of copper tubing with connector to attach the argon hose to - am I correct in my thinking ?
What are typical prices for smaller argon bottles (need pure argon I reckon, not the CO2 or Oxy mixes) ? Will also need a flow meter . Also am I correct in assuming that argon is 100% to use ?
Any advice's most appreciated :)