Drawing syrup... temperature goes up!

[KillerBee]

We just bought a used evaporator (3x12) last year. There is a big flue pan at the back... and two finishing pans at the front of the evap.

I know that lots of people are drawing just little bit of syrup at each draw, they open the valve at 7 and close it when it start to go down. On our evap, we can't do this... When our thermometer goes to 7... we open the valve... then it start to go up... sometimes up to 12!!! So to compensate, we will let draw until it goes down to 6. We normally have big draws off of about 3 gallons!

It look like the syrup is overcooked somewhere in the pan and is just right at the draw side... and I have the feeling it gives us a darker syrup this way...

We would like to have smaller draw off, more frequently but we can't get it right...

We check the level of the evap, and it's dead on...

Anyone have any advice on this?

[Thad Blaisdell]

using scoop and hydrometer, keep checking further in, when you get close to syrup further in start pulling in off, when you are no longer pulling off syrup or just below syrup stop drawing, use hydrometer in drawoff, say it reads 3 points heavy, take a bucket and get some hot sap from the flue pan to thin it down. DO NOT keep drawing off front pan to thin it down, no no no.

What is happening is you are pulling a lot of sap from the flue pan all at once and filling it with the same gradient. Then you are hotter in the center of the pan so you are making syrup there. So by doing what I am explaining you will set the gradient and should be able to have a steady trickle of syrup after that.

The other option is to draw off light to begin with, and set it aside till the end of the night, then the syrup will be right at the draw and you can draw smaller draws and that should also solve the same issue.

[KillerBee]

Do you mean that I have to check various locations in the pan?.. and when it's ready there ... start pulling it off until it goes right at the draw?

That would mean that the first draw would be too light... am I right?

Thank you for taking some of your time to help me understand my "new/old" evaporator...

[pamaple]

I have the same problem this year as well. Never had this problem with my old pans but these are cross flow which must be causing the difference.

[Thad Blaisdell]

Generally if you have syrup further in, it will be more than syrup by the time you get it out. Thereby fixing the lighter syrup. Once you get the gradient right you will have no problems.

Another thing some people do, is at the end of the night draw off a certain amount from each side of the front pan, then when you start back up the next time, you pour it back in on the appropriate side.

[Flat Lander Sugaring]

wood or oil? where is the draw point , in the front or next to flue pan. With cross pans I think it will be by the front.

If wood try to keep wood by the door and put some air to it. Like thad said at end of night draw a pale of sweet off set it a side. plug front pan so flue sap cant migrate into syrup pan (once it is safe). The next night start adding the sweet a little at a time and I add it to the draw point. Once all back in and at level you run it at unplug the flue and let the rig do the work. Keep an even hot fire. dont let it go way up then die way down like a roller coaster. Bring an egg timer into sugar house and set it for around 6 or 7 minutes, could be more. Add 6 drops defoamer to float every time you fire.

[PerryW]

This situation happens to me occasionally: Syrup develops in the middle of the front pan before it does at he the drawoff. I can usually see it happening as distinctive bubbles start forming when you hit syrup. When I see this happening, I start my drawoff early (maybe at 6 instead of 7 on the dial).

Not sure why it happens but you may have a hot spot in the center of the front pan so that syrup develops there first. Make sure you have a good hot fire evenly under the whole front pan.

[lpakiz]

Could you add a bit of hot sap to each of the front pan sections except the final one, thereby retarding the formation of syrup in these sections? So drawing a large amount to make the final draw correct would make the problem continue, right?

[ennismaple]

If your thermometer is stuck in the side of the front pan in the side compartment you're getting a false reading. When we got our Force 5 we put the probe through the hole provided in the side compartment and couldn't get accurate readings and always had large runoffs because that's a colder part of the pan. We got a temperature probe holder so we could position the probe vertically about 2/3 of the way down the last channel in the pan and now we get good readings and small runoffs.

[Bruce L]

How about using defoamer also? When Bruce from Leader was up last year,the draw-off would open,if the temperature started going up he would put a few drops of defoamer just before the draw-off port,tended to make the pan chase towards the outlet quicker

[KillerBee]

I've read somebody on this forum saying: "The more you know the more you don't know!" If feel that just the case here! haha! We had a smaller evap and we've always been doing batch boil like this... since almost 20 years... and we felt we knew a lot about syrup boiling... Then we buy a bigger evap... heard about continuous draw... tried it... and now we feel like we know nothing about syrup boiling! :)

I've been reading other posts, and I'm now pretty sure that my middle pan is hotter than my first one... And I guess that my thermometer (installed on the side of the pan) is not at the hottest spot either...

Anyway, we're going to boil this weekend... and I'll do some investigation on my pans with the hydrometer & thermometer... to see if the syrup is ready in the middle pan before at the draw off!

Thanks for your advices... i'll let you know the result of my investigation...

In the meantime, don't hesitate to continue sending advices!;)

[FameFlower]

We are learning our new equipment too. We have oil fired evaporator with continuous flow syrup pan that we can switch directions on with an automatic draw off. In this steamy picture, we just started the heating. You can see that the 2nd and 3rd portions are hotter than the side portions. Our probe is in the side (1st portion), which is much colder than the 2nd portion. If we drew off when the first portion is syrup we have caramel (or burned pan) in portion 2. We started drawing off when portion 2 is syrup (hydrometer test) and intend to finish it elsewhere and later (what that means we don't know yet).
7703

[maple marc]

I have struggled with this too. Got some good ideas here on an earlier thread about continuous draws. Check it out. A couple of things seemed to work for me this year. I start to draw a little early when I see the telltale bubbles upstream a bit from the draw valve. I might open the valve at 6, take a light cup off, then the next several cups are right on, then maybe a couple high, then a couple light. Doing this, instead of waiting for a 7, seems to avoid the surge you are experiencing.

Another thing to try is keeping your fire hottest on the draw side. Sometimes my middle channel seems to make syrup, but now when I open the door to stoke, I take a poker and move the hot logs over to the draw side and stoke in the middle. This seems to prevent syrup in the middle.

Marc

[Bobby]

I have seen this before. One time when I went to Bascoms during the sugaring season they were boiling on their custom evaporator. They were using a marcland auto drawoff and it would start at 219 depending on the barometric pressure and I noticed the temp would rise as high as 223. I asked the operator about the high temp, and he said thats normal due to where the heat hits the pan. Soon the temp would start to decline back as the auto drawoff started to close. The operator would test using a hydrometer and actually had syrup that was "too" done. He would simply add more "syrup" from the pan at roughly 215 degrees and constantly check using the hydrometer, until he achieved the appropriate density. Then he would simply mix the syrup as he added the diatomacious earth. So dont worry about the high syrup temp, just simply add more sap at a lower temp say around 215 until you achieve the appropriate density.

[PerryFamily]

I do the same. Draw off heavy, until the hydrometer reads perfect, immediatley head to my flue pan drain and adjust to be perfect. Sometimes it takes very little, sometimes more hot sap depending on how heavy it was initially. I shoot for a max of 1point heavy.

[maple flats]

And I also do similar. It works fine that way. However mine is limited to when I first start to draw. The temp. rises but then falls back gain. I draw slightly faster until it fall back to about +8, then I slow the draw and do my best to keep a constant draw and it usually gets to the +7 and can be kept there by tweaking the valve as needed. I own a auto draw off but have decided not to even hook it up for now, maybe sometime I will, I'm not sure, I like the constant draw method. My batch does not get adjusted from the initial surge of high density until I have a finisher full. Then I bring it up to filtering temp. and adjust. It usually is at like 120-140 when I bring the temp. up to 210-215 for filtering. At that point I density check and thin slightly as needed in most cases.

[nymapleguy607]

I have found with my evaporator in order to have consistant draws I need to try and keep the fire as consistant as possible. Big batches drawing off are a sign that the flue pan is taking a big slug of sap. Also when drawing off I only open the draw off valve to a trickle, my draw off temp will rise a couple of degrees but nothing too bad. I also found last year to avoid a big draw after starting the evaporator I take off about 2 gallons of sweet from the previous boil and adding that into the draw off box. This helps avoid the ripple effect of big draws. Remember if you need to add defoamer to the syrup pan only add it to the partiotion nearest to the side you are drawing from. Good luck

[maple flats]

before I had an RO and a 3x8 my draws were also barely a trickle. However now with an average of about 10% concentrate and the 3x8 with AUF and AOF, and high flues pan I can draw considerably faster. I draw between 7-8 and sometimes even more when I recirculate to concentrate even more, gal/hr. But, yes, the fire needs to be constant. That is why I fire every 9 minutes using a timer, fire as fast as I can, and only 1 side at a time and my wood is aged at least 1 yr, and split wrist sized. While my boil does slow while I fuel, it does not stop and it is back at full boil within about 3-5 seconds after closing the door.

[PerryFamily]

I have found that when I have help firing, and firing consistently every 5 minutes with a timer, I can easily make 5 gallons an hour.( 2x6 raised , AUF, 10% concentrate ). When by myself, I am lucky to be a 4 GPH. Seems like while drawing it needs wood, the the press inevitably spikes in pressure.....blah blah blah..you get it. Busier than a one armed paper hanger!!
Anyway, with some luck and more important money I can up grade after the coming season.

[wiam]

I have found that when I have help firing, and firing consistently every 5 minutes with a timer, I can easily make 5 gallons an hour.( 2x6 raised , AUF, 10% concentrate ). When by myself, I am lucky to be a 4 GPH. Seems like while drawing it needs wood, the the press inevitably spikes in pressure.....blah blah blah..you get it. Busier than a one armed paper hanger!!
Anyway, with some luck and more important money I can up grade after the coming season.

On my 2x6 I can have the drawoff valve and the fire door open at the same time

[maple flats]

I also have my draw valve open while firing (3x8, 8-12 and sometimes even 14-15% concentrate). Even though the boil at that time may slow, the density doesn't change instantly because of it. Keep the draw if you are trying to do constant draw.