Block vs Metal?

I need to build a new evaporator/arch... Can't decide on a block one or a metal framed one..
Any pro/cons?..

My first was evap was a combo: pickup work box surrounded by high-temp insulation surrounded by blocks. Worked ok until the work box melted (aluminum). Next season, the plan is a steel box (file cabinet) surrounded by insulation surrounded by blocks. Insulation kept heat in and kept bricks cool.

The more conventional order seems to be: Metal box, lined inside with insulation, with firebricks inside that. I suppose you could surround all of that with cinderblocks, but it seems like overkill.

Having your pan up at body height would be so much more convenient that bendong over. Just something to think about.

Mine was built by some welder...who knows when, out of heavy 1/4" plate and angle. It was a bear to move. Even with all the bricks removed it had to be rolled slowly on planks and rollers. It's very stiff though, and can be levelled with a big pinch bar without worrying about cracking the bricks. It will probably last for 100 years.

my question would be are you a back yard boiler that you have to take it apart and move every year or can it be built and not moved around much? I prefer steel if you need a portable one that you need to put away you could build a steel frame out of angle iron that could be welded or bolted together and put tin around the outside that wouldn't take up much room while it is stored

I've been pondering this question for years. I'm a bricklayer and have all the materials I need to build an arch out of masonry. Basically for free. I've decided to make one out of angle. I just like the idea of being able to move it if I ever have to. And it takes up less room. For a proper masonry arch to be built and hold the heat you need mass. I had one planned that used 8" lightweight block ( higher fire rating) filled with lightweight concrete. ( Portland sand and vermiculite) and 2 layers of fire brick. It was almost 41" across to hold a 2' pan. Took up way to much room. And then I would of had to put angles where the pan sits anyways. A steel front for the door. Steel grate under fire. And a steel chimney. So I decided to go steel for everything. I'm building it this summer. And you will also need a solid foundation.