New block arch and test boil questions.

[Leo]

Hi, I finally got my new block arch put together. I put my new 34" x 64" flat pan on it and did a test boil.
It took me about 55 minutes to get the boil started but I think I may have put too much water (25 gallons - 2.25 inches) in to start.
I boiled for one hour and then it took about 1 hour to cool down afterward.
I added 5 gallons to the pan during the hour boil. I was adding cold water in a trickle, but have plans to hang a preheater pan in a corner of the main pan.
At the end of the cool down I measured the water and found I had boiled off 18 gallons.

The pan never boiled much more than half of the way back to the stack and never really got hopping. Why?

My stack is 8" stove pipe 10' tall.
At the back of the arch there is three inches of space below the pan - is this too much or too little?
I did put a "shanty" cap on the stack would that impede draft? The entire arch is insulated with 1" Archboard and the fire box is lined with fire brick.
Thanks for any feedback!
Leo

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[smokeyamber]

Nice looking arch ! Should work well, you could play with the gap and maybe close it up and see what happens. If you could run a blower that certianly will help alot. Taking the cap off the stack for boiling is a good idea on your part as well,you could also go taller for more draft The round exit could be keeping the heat off the back of the pan a bit, if you did a wide exit that also might imporve rear boil. Some use square heating duct that have a round outlet as a flue. Overall I the current setup should crank with dry wood. Maybe also play with the door open a crack...

Have fun boiling !

[Peepers]

Nice looking arch Leo - I agree that you should try without the stack cap on. From the pics it looks like your exhaust has to go down a bit then up the stack, is that correct? Maybe laying a 12-18" long piece of angle iron at the end of your ramp would keep the heat under your back pan a bit longer before shooting right up the stack. A little turbulence is a good thing rather than a straight shot down the middle and up the stack. It looks like your ash cleanout area is wide open so you should have plenty of combustion air - I bet that once you take that stack cap off and create a little turbulence you'll be boiling on the whole pan.

I'm thinking that I might try a leaf blower on my arch this year when I'm first firing to get it heated up faster. Once the fire gets big and my stack/blocks get hot the draft gets going good and I get plenty of heat but I'd like to shorten the time between lighting her up and making the stack glow. :)
Keep us posted on what helps and what doesn't!

[valleyman]

Nice Leo!
I'll have to show you my new grate. You gonna warp that one before long. This season I'm using the steel channel that DEP use for the road signs. It has holes in it. If you can add more holes with ease, that would be even better. I'll get a pic to you.

As far as the arch, take the cap off for sure. Also I know the arch designs all have a narrow gap for the rear pan. I actually had to open the airway up by taking a row of firebrick off. That made a huge difference. Then I added air from the underside and that got all four boiling well. All I'm using is a small desk fan blowing in under the fire. I tried with a more air and it became a fire hazard with ash flying out of the stack. It was an inferno boil at that point but had to back off the air.

That being said, adding forced air under that bad boy will be the ticket. It looks really nice. Glad I was able to help. This site is full of generous and helpful folks and I learned it all from here. I boiled roughly 25 gal on Sunday down to just over 1 gal in about 2-2.5 hr. not to bad.

[Ausable]

Hi Leo - - That has got to be the nicest looking Block Arch I have ever saw. Very nice work. The other Guys gave You some good advice so I really can't add anything there. The more You boil on it -things will become apparent where to tweek it to impove the boil. Again - very nice work and make lots of good maple on your new rig. ---Mike--

[palmer4th]

How did you make the block that is around your stack pipe?

[Leo]

Thanks for the input and the advice everyone. I will try some experimentation with the height of the ramp and with the stack. I do have a little box fan that should work for forcing some air in though the ash cutout.
Everything that I learned and put into making the arch came from information and pictures shared by others on this forum. I retired last fall and have been looking forward to this for years.
Thanks,
Leo

[Leo]

I made the block for the stack by making a wooden form the size of the block I needed and then putting an 8" stove pipe slip joint in the middle of it. Then I mixed up Sacrete concrete mix (it took 1.5 bags) and carefully filled the form around the slipjoint. Because I screwed the form together, it was easy to disassemble it to get the block out after 48 hours of curing.

[Maplehobbyist]

Nice looking rig. I wish mine looked as good.

From what others on this site told me when I was constructing my arch, the area of the stack should be about the same as the cross-sectional area of the most restricted spot between the firebox and the stack. Your stack is 8" = 50sq" (3.14x4x4) while your most restricted area looks to be about 90sq" (3x30). I don't think your stack is big enough to get as much heat as is needed to boil at the rear of the pan. (I know, just what you wanted to hear, that you need to spend even more money, right?) Plus, when the exhaust leaves the firebox and goes to the stack it narrows to a point, so it's hitting all across the width at the front of the pan but only a narrow area at the rear. I could see this in mine from the soot pattern. Maybe some strategically placed fire brick under the rear of the pan would help, both to create the turbulence that others have mentioned and to force the heat out to the sides at the rear. I did that and now I get a pretty good boil in my rear pan, which is only heated by the exhaust.

It also looks from your pictures like the exit for your stack is lower than the level of your brick under the rear of the pan, which means the exhaust is never forced to run along the bottom of the pan, it just travels along the top of the brick. Maybe in that situation 3" is too much space. So those strategically placed bricks could also help with that.

As far as removing the stack cap, I know a lot of people on this site don't use them or have them hinged so they can be removed during a boil, but I would be careful about removing something that is a safety feature, just for a boost in performance. Maybe your evaporator is located in an area where sparks aren't a real great concern and it won't be a problem. Those are questions we each decide for ourselves. Good luck with your experimenting. That's half the fun of this, figuring out how to make things better.

[Leo]

Hey, thanks for the thoughtful feedback Tracy. I am going to burn a little more wood and do another test boil. I think I am going to add two feet to the stack; mess with the amount of space under the rear of the pan; try some turbulence to force air to the sides and play with a little box fan I have to blow some air under the grate.
I would like to avoid changing the stack (this year); the financier might get cranky.

[sugar ED]

Leo, Looks sweet !! All good advice ,Also a 1 hour test is a short test . mine is just starting to warm up the brick at 1hr, but after 2 + hrs. the brick are red hot and total pans boiling (even in rear,where cold sap enters) Takes about 3 to 5 hrs. to cool down !
not sure what kind / size of wood and how often u refire, But all will make a differents .
I use DRY wood (cut the year before) ,wrist size pieces ( split 2 " to 3 1/2" ) , and refire every 6 to 10 min. and start shutting down, when I get down to 150 gal of sap ,as to not run dry durning cool off .
Good luck sappin !!!

[Leo]

Hi Ed, thanks for the information about the length of boil. I do have all two year old wood, but didn't have the splits that small. I am going to add to the stack and play with the air flow when I do another test boil this weekend.
Thanks, Leo