Block vs Metal?

[Bill'sSugarShack]

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

[ScottyWelden]

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.

[bkeith]

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.

[11-Nick]

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

[Michael Greer]

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.

[chad]

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

[Bricklayer]

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.