Looking for dimension suggestions for 275 gal tank arch

[HyeOnMaple]

I want to make the fire box as small as possible, but am not sure what proportions to make the arch. If the whole thing is 8'6" to the back of the stack, what if any is the minimal size that I can make my fire box (and if I make it small, can I boost its efficiency with AOF and/or AUF? :confused:

Thanx.

[twin6]

I don't have dim's handy for the oil tank arch we built last season, but we used a standard (US) oval tank and it yielded about 11 sq ft of gross surface area for the pan, not extending beyond the cut we made. I believe we made the firebox floor 24" deep (no deeper). We have a pretty steep arch/ramp. Keep in mind that longer sticks will go in ok as the height of the fire increases, because of the ramp. IMHO, you should keep the distance between the fire and pan(s) as close as you can, and still have it draw ok. Proper insulation (ceramic blanket) and a preheater will boost efficiency, and are well worth what you invest in them. We are adding a preheater this year, and next year will plumb up the stripped down furnace gun we have for AUF. Big firebox and big stack often add up to inefficient rigs that consume way too much wood.

[TerryEspo]

I kinda asked the same question a few weeks ago and most said the make the firebox a bit larger than you think you need. You can always raise the grate, add more firebrick etc. to make it smaller, real hard to make it bigger.
Its also nice to calculate brick size and insulation for brick placement once completed. Saves cutting bricks and having to use pieces all hacked up. I calculated to have an extra 1/2 space all around and still a bit tight in places.

Good luck with your project, you will feel good doing it.

Terry

[twin6]

Just measured ours and it is 17" deep, brick to brick, at the grates; it's another foot deep at the top.

[Pete S]

6610661166126613

I am too lazy to go out and measure, BUT will if you like. I have attached some photos to let you see what I did.

[Vermont Creation Hardwood]

My arch was made from a used oil tank, but not a 275 gal, a bigger one, 325 I think. It's the same height and width, but longer than the standard 275. I have two pans in it. I cut out for the pans all the way back to 8" from the end to get maximum heat transfer. The front end piece fit perfectly into the cut at the end. The rounded side and top piece cut out I split in half and put inside the side walls spacing them 2" away with bolts. This space i filled with ash for insulation.

I use no grates and make the fire directly on the ash bed. So the firebox is insulated on the sides and bottom. No bricking necessary. I boil in batches. The front pan boils much faster than the rear, flue pan. I add sap as I boil till I run out or enough goes through to make two gallons syrup. Then I let the fire go out and keep stirring the embers till I'm down as low as I dare in the front pan. By this time I've emptied the rear pan into the front pan and refilled the front pan with water. That way I can scrub the rear pan with hot water. When I'm down to a half or an inch in the front pan and I've timed it right, the fire is mostly out. I draw out the near syrup to finish on the stove in the house and quickly fill the pan with water. Then I can scrub the front pan with hot water too.

My stack runs 300 degrees or so, so I'm not wasting the wood I spent much labor cutting. Sure it boils slower, but I don't have to sit there and watch it, just feed it as often as I can. I do many other things while the sap boils, so I'm getting more than one thing done at a time. This slower firing never foams, never boils over, never burns. It doesn't require constant attention. If I want to sleep at night it will slowly evaporate the night long if I fill the firebox. I usually can do a batch in 24 hours and that includes sleep time.

6614

[jimbo]

Started mine last night. My pan is 2' x 4' with a preheater, but the sides of the tank are 27". I plan to use 2" angle iron to fill in the space on the sides (like Pete S). Will this work or is that too much pressure on the welds due to pan sitting on the inner edge. Also worried the angle iron will slowly fold down due to heat. Any ideas? Also, is ten feet of 8" stack overkill. Will I just be burning my wood supply to heck. Thanks, jim6619

[psparr]

Started mine last night. My pan is 2' x 4' with a preheater, but the sides of the tank are 27". I plan to use 2" angle iron to fill in the space on the sides (like Pete S). Will this work or is that too much pressure on the welds due to pan sitting on the inner edge. Also worried the angle iron will slowly fold down due to heat. Any ideas? Also, is ten feet of 8" stack overkill. Will I just be burning my wood supply to heck. Thanks, jim6619

I have a similar setup. 27" wide with 2" angle gives me 1/2" bearing for the pan. I ran ceramic blanket up to the angle and toed it in to protect the angle.

I have ten feet of 8" and I get great draft. My syrup pan boils so good that sometimes I need to close the draft door a little. My rear pan doesn't boil so hot but I'm feeding cold sap. 6622

[psparr]

Here's a couple more of the build to give you some ideas. 662366246625

[HyeOnMaple]

Wow, guys! Great pix and great ideas. I was going to try to frame the inside with bed rails, but it seems something beefier is the way to go. Besides Home Depot and Lowes, where is the best place to get angle iron cheaply?

[psparr]

If there's a scrap yard near you they will usually sell to individuals. Just explain what your doing. They will probably be pretty interested. You should expect to pay around .40 a pound.

[backyard sugaring]

Mine is built out of bed rails never had a problem. The hardest part is cutting and drilling them. The best part is they are free. They also don't rust. Good Luck. Lee

[jimbo]

Thank you all so much.