Simple block arch question re boiling

MY DH finally found the time to put together a small block arch for me that holds 2 SS steam pans. Which pan should be the *hot* one, front or back? Or will they both boil at the same rate if sap level is equal in both and the fire is built in the right place?

Our test run last PM seemed to work nicely. Got about 2 GPH boil off rate but that was in the dark with fear of scorching the sap so we didn't torque up the fire as much as we probably could have. We built the fire to the front and the rear pan was the hot one. But for some reason I'm thinking it should be the opposite??? Or is the firebox too short in a 2 pan set up that it doesn't make much difference?

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Originally Posted by happy thoughts

Or is the firebox too short in a 2 pan set up that it doesn't make much difference?

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I would say you were correct with this statement. The firebox is pretty short so both pans will likely be "hot". If the back one seems hotter it's probably due to the fact that you have a good draft pulling the heat to the back. Don't fight it, there's no rule that says the front pan needs to boil harder than the back.

Depending on how you are set up, the front pan can be much cooler. Especially if you have an open front. The draft pulls a lot of cool air in over the fire. If you can make it work, set it up so you block most air and force the flow in under the fire grate and up through the fire. The rear pan may still be the hottest one, but the front pan will boil well.

Thanks guys. Much appreciated:D. I think the arch finally got my DH interested in sugaring :lol: He's already thinking about how to build it better next year.

riley- I assume you mean some sort of metal arch front? Any suggestions? My DH is handy but doesn't have a lot of metal skills. We'd need something that could be made with simple tools. Would aluminum flashing or sheeting work, or wouldn't that be able to take the heat?

HT - I use a simple 2 pan block arch as well and can boil up to 6gph even without a preheater. Attached are a couple of pics of it in operation from this year. It has a firebrick lined firebox with a small arch in the back. There is also a grate that is raised up one brick heighth - 4 inches. You can see both of my pans will boil, but like yours, the back pan is definitely hotter. Oh, and my door is an old metal chair seat! You can see it is raised at the bottom for air flow into the firebox.
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Thanks, cy. That was helpful! That looks pretty much like our set up. I'll have to send my Father in law dump diving:)

I have a blockarch also. My "door" is a cement block with the two holes open to the fire and another cement block on top to "seal" it off. To load wood I just remove the top block, load, and replace the block. Wish I could post a photo. I'm kinda limited in the computer skills area. I'll see if my dear sweet wife has the time to help.

Something as simple as a half of knock down rectangular ductwork sheet metal can work. Hang the short leg on the front of the arch and let the long leg block the top of the opening. Take another and slide it across the front the close the door. Use some extra blocks to hold it up and keep the draft open under the grate.

I used to take one that was formed in an L , like this:

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thanks to all! Second boil on our modified arch seems to be really improving the boil rate. Boiling great right now. Amazing what a little shielding does in directing air flow. My front pan is bubbling just like you said it would Riley, and BTW I'm really impressed by your knowledge of fire dynamics. I've learned a lot about fires from reading all your posts. Last week AUF was the sound my cats make throwing up hairballs. Now it's a whole different thing:)

tbear - I have been running a block arch like you describe for a few years now. If you have a decent cross-breeze you can angle a spare block on the ground to direct the breeze into your open block and get a little natural forced air. :) I don't know if it really helps much but I like to think it does! This year I have an old (and really heavy) metal door ready to be cut up and used as a more efficient and durable door probably like Riley is describing as I won't have time for anything fancier. Even with natural draft we chuck enough wood into the fire to get the stack to glow and in doing so the "door block" never makes it to the end of the season before crumbling.

Glad to hear you're running good Happy Thoughts! I too have learned a lot from Riley's adventures over the years. :D

Last year was my first attempt with the block arch. I had it set up for two pans and couldn't get the front pan to boil with the open front (way too much cold air). I just turned a couple of stacked blocks to cover most of it and had a perfect sized piece of steel around the house which I used as a sliding door and for "draft control". Helped the front pan tremendously. This year I have made it longer (to fit three full, and one 'half size' pan), and really built up the arch with sand and set up some U - channel (with lots of holes) under the steel door that goes under the fire. Hoping that will get more air in there. If I get really bored, I can pump the bellows into it. :) First boil this weekend - we'll see!

Last years block arch:
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Originally Posted by Peepers

tbear - I have been running a block arch like you describe for a few years now. If you have a decent cross-breeze you can angle a spare block on the ground to direct the breeze into your open block and get a little natural forced air. :) I don't know if it really helps much but I like to think it does!

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That's where my DH started. We had some 4" block that was about the same height as the fire grate. That seemed to help direct air under the fire when the arch front is partially blocked off. A few blocks stacked to the sides and an old metal garbage can lid for a door made loading the firebox pretty easy. We also added some aluminum flashing across the top and front where the pans ended to seal that area and bent the top edges to fit inside the block to secure it. Wasn't sure if aluminum would work or not. It's melting point is only about 1200F but it ended up working pretty well this time. We'll see what happens when my better half really gets crazy with fire:)

I have a 3 pan set up on a block arch. My back pan is always my hottest.

I also have a set up with steam table pans with 3 pans on a old oil tank and How do you guys empty the sryup when its finished??

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Originally Posted by G&D MapleSurgaring

I also have a set up with steam table pans with 3 pans on a old oil tank and How do you guys empty the sryup when its finished??

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Well you will have to get the pans off of the heat quick.Welding gloves? I would probably finish on another heat source. I use a large flat pan, I simply slide it off the fire onto the wheel barrel.

I gradually boil down to one pan, then ladle/pour into kitchen kettles. Those I finish off on my kitchen stove. I can better control the temp. there and keep an eye on it with a themometer. Wish I had a better way to empty those steam table pans. Haven't found any other way yet.

I realize they will still be hot. But how about taking a muffler clamp on each side with the "U" pointing up. use two nuts on each stud to lock them down tight. Position these off center each way on the sides so the pan will not be balanced. (Slight diagonal to center)

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Originally Posted by happy thoughts

MY DH finally found the time to put together a small block arch for me that holds 2 SS steam pans. Which pan should be the *hot* one, front or back? Or will they both boil at the same rate if sap level is equal in both and the fire is built in the right place?

Our test run last PM seemed to work nicely. Got about 2 GPH boil off rate but that was in the dark with fear of scorching the sap so we didn't torque up the fire as much as we probably could have. We built the fire to the front and the rear pan was the hot one. But for some reason I'm thinking it should be the opposite??? Or is the firebox too short in a 2 pan set up that it doesn't make much difference?

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I ran into the same problem with my 3 pan setup. The middle pan seemed to get the hottest while the front pan ran cooler because too much heat was escaping out the front. The following year i extended the front by adding another row of blocks and then instead of a pan at the front I just covered it with a piece of sheet metal. Another piece of sheet metal served ad a door. Now I get a good boil on the first pan.

Hi,
Here are a couple of pics to show my block evap set up. Below are some tips i've learned either through this site or trial & error.

1.Run you pans deep with sap if they are set into the firebox like mine. This minimizes scorch line of burnt sap.

2.Pop rivet handles on the steam pans. Big help moving them.

3.A very good investment was a flat syrup/sap scoop. This allows almost all sap to be removed with minimal loss.

4. I would use plate steel for a door. Aluminum will warp and/or melt.

5. Keep a lot of air space under your fire grates.

6.When boiling, I fill all pans with sap, then start boiling and the ladling process moving the sap to the front pan (which burns the hottest for me). Once the rear pan is all scooped out, I flood the rear pan with water. I continue to transfer sap and filling the empty pans with water (from rear most pan on up) until the front pan is the only one remaining with sap. At his point I let the fire burn down. Once the fire is down, I'll lift the pan out and transfer golden sweet sap to a container to finish on propane. If you lift the pan while a big fire is going, you'll create draft and you will get a lot of soot and ash flying around and landing in the pans.

Hopefully this is helpful.Attachment 6302Attachment 6303