How hot do you go?

[danno]

I have this issue every year.

I reach syrup per my hydrometer at 221 degrees off my syrup pan - so that's when I begin my draw. Syrup temps often reach as high as 230 before temps begin to drop. I continue the run with thin syrup till the whole draw balances out as syrup.

Occasionally I have a nice 1 to 2 gallon draw where the temps will stay between 221-223. I like those. But those 5-6 gallon, 221-230 degree draws I'm not so keen on. When that happens, I want to draw quicker to get that syrup out of the evap. but afraid of a scortch if I do.

I've tried drawing early and draw the thin before the thick, but that just never seems to work out. It's much easier to thin over-thick syrup than visa vesa.

So, I'm sometimes drawing as high as 9 degrees over syrup. How hot do you go?

[Amber Gold]

Frequently when I drawoff the temp. will increase to well above the boiling point of water (ABPW) for short. I typically start my draw at 8F ABPW and watch it climb to 10-11 ABPW and will drawoff about 1 gal. Sometimes 2 gal, but that's usually the first draw of the day. The end of the day I'm only 2-4 Br. heavy so not too bad. This year when it hits 8F ABPW, I crack the valve and will drawoff over 15 min+/-. It allows me to do other things while drawing off, also it turns into syrup as it gets closer to the drawoff...seems to work pretty good and I don't tend to lose my gradient as much in the syrup pan as last year when I'd drawoff in a quick dump.

To get 5-6 gal draw you must be making syrup in 3/4's of the pan. That seems atypical.

[PerryW]

If my dial thermometer reads more than three degrees above where syrup is coming off, I immediately stop my draw-off and grab a dipper and ladle a pint or two of hot sap from the back pan into the area(s) of the front pan that look like they are beyond syrup. With practice, you can bring the dial thermometer back down where it belongs and continue the draw-off.

[sweetwoodmaple]

Another idea to help troubleshoot is run a second theremometer earlier in the finishing pan and therefore monitor temps in two places.

If you are starting to make syrup in a previous partition before the draw off point, you will have to work on how you fire (which I am still learning).

But in the mean time, you will know when you should start drawing off to help avoid the rise in temps.

[mapleack]

Danno, it sounds like you're syrup is being made one partition over. Have you checked level lately? Is the pan very warped? Just my ideas on the 230 deg problem.

[Jeff E]

Sap depth, warped pan, uneven boil based on arch wall thickness interfering with heat transfer to outer partitions all can cause this.

Danno, How deep you running? Are you outer partitions 'sheilded' from fire due to firebrick thickness?

[danno]

Because of this problem - I've been running the syrup pan 1.5 to 2" deep. Pan is not warped. I used 1/2 firebrick on the top course to help heat transfer to the sides of the pans.

My 2 middle dividers boil/foam way more than the two outside dividers, especially the 3rd divider before just before the draw off divider.

Will adding sap from my flue pan to the dividers that are at syrup cause scortch? Thought I remember hearing that somewhere. I've got to find a good ladle with a long handle or a turkey baster. It's darn hot under that hood.

[tuckermtn]

Danno- that is exactly that is happening to us- middle two dividers the bubbles look like syrup - but not in the last partition- we typcially are drawing off 1.5 to 2 gals at a time- we are running deeper also- 1.5 to 2 inches.

haven't quite figured out a rhythm with boiling the concentrate yet...our draw offs seem very erratic and our density is pretty irregular...

sorry no answers, but a shared expereince..

what % are you putting in?

[Gravel]

I would definately put a thermometer in one of the 2 middle dividers and if it turns to syrup there before the drawoff divider I would just draw off until you get to the syrup, shut off the valve, put that back in the divider furthest from your drawoff and then drawoff the syrup, that may work?

[northwoods_forestry]

My first drawoff is similar to what you describe, a lot at once, but once past that I try to get to the point where I can drizzle it out constantly, adjusting the drawoff flow to the the point where I maintain a consistent temp at a drawoff, usually at +6 degrees. Doing this requires consistent firing that maintains a consistent stack temp. Some nights it works great, on others, not so great. Note the consistent use of the work consistent...consistency is the key, I think.

I too get the best boil in the center of the syrup pan, and had thought about changing the bricking to get more heat to the sides. I haven't had to, though, as I've found that I am able to create and maintain a gradient even with the harder center boil.

[Snow Hill Farm]

Related to this, last night I had a very difficult time controlling foam and could not stop it from coming to the top of the middle dividers (3x10 w/forced draft, all hardwood). It seemed like the intense heat in the firebox was the problem so I tried a smaller fire (helped some) but had to keep adding defoamer in the front (which I know is the last place you are suppose to add). Then the draw off temp (auto draw off) would go way down and sit there for an unusually long time and then shoot up for a big draw. I did read that this is a result of too much defoamer. Previous to this the rig was running really smooth all season. A friend and I literally had to stand there with defoamer the last few hours to make sure it didn't go over the baffle. Any ideas?

[northwoods_forestry]

How deep are you running the syrup pan? Seems the deeper I run the more likely it is to foam over the baffles.

[Snow Hill Farm]

I would estimate 1 1/2", any less and I would be worried the foam would pull all the liquid off the bottom. It was really frustrating not being able to take your eyes off it to do the other chores.

[northwoods_forestry]

Yeah, definately don't want to go below 1/2", I'm with you there. How's the bottom of the pan looking? Does it need a good scrub?

Trying to think what else it could be, but I'm drawing a blank. Might just be the sap that day?

Last year my helpful 6 year old daughter cleaned out the gathering tank for me. She dumped the better part of a bottle of dish detergent in when I wasn't watching and gave it a good scrub! Talk about foam!!:lol:!!

[Snow Hill Farm]

I have only boiled twice since last cleaning the pan and my kids haven't added anything to the tanks (that I know of!). I'm really scratching my head on this one and need to figure it out fast because I will be boiling all day Sat. and Sun...

[danno]

Allot of us sharing the same problem. Consisitency in firing is certainly a problem I have. I need another set of hands - running the evap, sap pumps, RO, checking sap levels, filtering, cleaning filters - whose got time to load firewood timely:)

So far, the best solution sounds like adding sap from the flue pan into the middle dividers if it gets to syrup before the last divider. Any problems with that? Scortch?

I don't think I need a thermo. in those earlier dividers, from the bubbles, I can tell if those dividers are at/near syrup.

[Snow Hill Farm]

So I boiled all day today without a hitch, Thurs. night the foam wouldn't stop coming up (and almost over) the middle baffle in the front pan. I heard there was a pressure change when I was boiling the other night and that's why I had so many problems. Just glad today went smooth and I only put defoamer in the inlet to the flue (2 drops after every fire) and never had to add to the front during 10 hours of boiling.

[Brent]

Danno here's a new theory. I don't know your rig but most evaporators I've seen are wider at the top rails than at the bottom, and some even taper in to the level of the grates and then flare out up to the top rails. So the grates are several inches narrower than the pan. All the grates I've seen have uniform spaces between them, letting air up through. It seems logical that the best draft up through the grates will be in the center and therefore the pan will get hotter there.

Maybe try laying a few bits of brick or flat steel bar to partially obstruct the air going up throught the center sections and encourage more up through the outer grates.

Certainly the center is going to be hotter just because of the spread of radiated heat from the fire.

[danno]

Brent - you're on to something. I was troubleshooting while I was boiling today - with the same problem, two center dividers reaching syrup before the last. The only draw I don't have a problem with is the last one of the night as I'm shutting down. As I'm shutting down, I usually have my blower off as I'm easing down.

I run a big blower - 1100 cfm furnace blower and it's centered on the two center dividers. I think that's my problem. I'll try some modifying tomorrow. I've got to get it right, cause this problem is getting old fast.

[maple flats]

Yes, try spreading the air flow better. On my newly designed set up I added high pressure air over and under. The under air is from one 4" pipe with 3 rows of 3/8" holes so one faces straight up and one row towards each side. I now get a very even heat and boil once everything is going good. For the top air, I made a manifold with 1/4" pipe for nozzels and they face down 10 degrees and run every 6" from right next to the doors all around and to the other door. Each side faces straight out of the manifold. This is doing very well. I then have a 4" pipe bringing HIGH PRESSURE air from the blower outside, to a Y and thru a ball valve for each to regulate the balance going to each, under and over. This year i am getting the best burn I've ever gotten and my fuelings have gone fron 5 minutes to 20 and I am using much less wood. Something like this will likely solve your problem but unfortunately you could not do it during the middle of the season without loosing a few days. Good luck. For this year I would just try the fanning of the air spread under the fire. Mine for that is just a 4" galv stove pipe about 26 ga with the 3 rows of holes. My 3' wide rig is the older style with a narrower bottom, if yours is wider at the bottom than mine try 4 rows of holes to spread even more. This summer I am going to cast a refractory floor as suggested in the report I got my air plans from and then my floor will have 12 air holes/sq ft, over the entire floor except none in until 8" back from the door. That is another point, my 3 rows of holes don't start until 8" into the pit from the front.

[danno]

Hi Dave - I have a similar design as yours, thought not as elaborate. I already have the refractory floor with 3 3/4" holes in each brick. I'm gonna replace some of those middle bricks with bricks without holes to try to spread the heat.

I also have air above the fire - but I'm gonna switch fans. Gonna direct the smaller fan under the fire and the big fan over the fire. We'll see ...