evaporator set up

[ash10383]

thinking about how to do our boils most effiecently: what we are thinking about using: we have a sort of fire ring: husbands family uses it when butchering / making lard its a steel bent in a circle with a chimney on the back and door on the front for fire tending, then they have a cast iron kettle sit on the ring. We are debating between modifying it to have a grill on it to set our 3 steamer pan or to use a copper kettle. we haven't done any exact calculations but we are pretty sure the kettle has as much or more sq ft surface area as the steamer pans (we know to keep it to just 4ish inches in the kettle, that is correct, right?)...is one option better than the other? is the steel enough or should we think about adding some bricks / blocks around the outside of the steel? TIA!

[psparr]

You want to keep your level of sap as low as you feel comfortable. The lower, the faster the evaporation.
But I assume the kettle has a bowl shaped bottom, that doesn't lend itself to that.
However, if it is all copper, you'll get much better heat transfer than the stainless steam pans. But running the sap low in the kettle will allow heat above the sap line burning sugar to the inside of said kettle. It's a real pain to remove it
Insulation will help keep the heat where you want it. Brick is really only used to protect the insulation from tearing when you load wood.
Good luck with whatever you decide!