Block Arch Designs?

[chuckinduck]

Hey Guys I am prepping an area on my property to build a block arch. For the past two years I've made my maple syrup w/ just a standard block arch of stacked cinderblocks lined w/ firebrick. This year I want to pour a concrete pad and cement the firebrick/cinder block all in to make it more permanent. My chief concern is the durability of the cinderblock over time, so I was wondering if I should line it w/ some kind of blanket or gasket material? Is there any pitfalls I should be concerned with? My other concern was how to do the flue? I was thinking of two stacks of stove pipe out the back of the block and mortar them in w/ a fire retardent mortar. As for the door, I'm not quite sure on what I'll use there, but I was thinking one of those cast iron door kits you see at TSC for barrel stoves? If anyone has any insight on this or pics of their design I would love to see them. Thanks. Ryan

[Middleton Maples]

I could help you out a bunch since what you described is how I made syrup my whole life and my profession is masonry. My father and I always tried new innovations to make it work better but its hard because the masonry just doesn't last (about 2 years) without being repaired. This year will be the first year we wont be making syrup that way but I wish I took pictures of our masonry arch before I tore it down to make room for a new one. I have a lot to say so I'll try to break it up.

[Middleton Maples]

First of all unless you have old block, they don't make cinderblocks any more, its now cement block. What kind of pan you have, is it just a flat pan. The best thing to do to help insulate and prolong the firebox is to first build the shell of it out of the block. I used 8 inch block to get it off the floor and then used 4 inch block for the walls. Make sure the 4 inch block is cored and not solid, you need that air space for some give. Once you get the block up, core fill the 8 inch block with concrete so the floor of the fire box is flat. Now you insulate. The best way to insulate is to now line arch board all within the fire box, the floor and walls. If you cant get arch board there is an alternative.

[chuckinduck]

THanks for your insight, and yes, when I say cinderblock, I actually mean cement block. But now you got me second guessing the process of pouring a pad and cementing in my existing arch if I will have to replace it all in two years. That fire brick is too pricey to only get 2 seasons of sap making out of it. What is it that causes the arch to break down? Is it the amount of heat the arch is exposed to? As for my pans, I have two buffet stale chaffer pans that hold about 8 gallons of sap at a boil. For my small production, its all I need, I only run 15-20 taps so we're not talking some big huge production. THanks for your help and insight.

[Middleton Maples]

Now when I say you might have to fix the arch every now and then I basically mean re-cementing the bricks or block you shouldn't have to replace them entirely. Basically the reason why the masonry breaks down is the heat. Heat expands and contracts when it cools making the cement break down and un-stick. One other thing you should do is use regular masonry cement to hold the blocks together. Then use refractory cement to hold the bricks together. Make sure its the dry mixed refractory and not the already mixed refractory cement. When you lay the bricks lay them in just an 1/8 inch bed of mud. I have pictures of how I laid my bricks in my last post take a look.

[palmer4th]

I made a block arch last year and it worked great! I may add insulation though this year. and a blower

http://s1126.photobucket.com/albums/l603/palmer4th/Shilsons%20Sugar%20Shack/

[Bernie/MA]

If you have access to a welder you might be able make a steel box that would last longer and not cost much more. I've made some. A furnace oil tank works good too. I made one with double walls with sand between that's been used 3 years and still looks good.