How to adjust float valve during draw off

[mspina14]

OK. This is my first year using a "real" evaporator and I still have some questions.

I've now boiled about 400 gallons of Red Maple sap and made about 5 gallons of syrup.

I've been able to "master" the balance of sap flow, sap depth and wood firing timing during syrup making. I can now have a stable depth of sap in the float pan (about an inch over the raised flues), and a stable depth of sap in the syrup pan of between 3/4-1 inch.

I use a thermometer to measure temperature change. But mostly use a refractometer to test the density of the sap frequently during a boil:

16222

So I've been able to adjust the flow of sap from the flue pan to the syrup pan to keep the sap between 3/4-1 inch in the syrup pan and continue to evaporate water from the sap to increase the density to 67 brix. There's a little "handle" on the top of the flue to sap pan float box that allows for adjustment of the float to control the flow of sap into the syrup pan:

16223 16224

My problem comes during draw off. When the density of the sap hits 67 brix, I open the draw off valve slowly to get a follow of syrup into my draw off tank equal to the width of a pencil lead. But now everything is out of equilibrium!

The syrup in the front channel drops to about 1/4". Sap starts burning. Smoke fills the shack, and I invariably have to reach for the OS bucket of water to prevent a burnt pan.

I've tried increasing the flow of sap from the flue pan to the syrup pan before I open the draw off valve. But it takes time for the fresh sap to make its way to the front channel of the syrup pan. If I open the valve from the flue to syrup pan and wait a minute for the sap to enter the syrup pan, it dilutes the syrup in the front channel to the point its density is now below 67 brix and I no longer have syrup :(

What's the trick to keeping me from burning down my sugar house during draw off? :confused:


Thanks for any advise.

Mark

[jmayerl]

That seems like a dangerous low level for someone new at running a evaporator. Go deeper in the front to avoid costly mistakes

[mol1jb]

I don't have the answer to your dilemma but I do have to say your float looks home made and fantastic. I would like to get the materials list to replicate that. Great work!

[saphead]

Haven't drawn off by hand for a while, but when it gets to syrup you don't want to play with it,open the valve and get it out before it burns! This will cause a much more rapid response in your syrup pan level and hence your float will respond quicker. Play around with your levels...deeper sap in the flue pan means more head pressure and faster flow into the syrup pan,deeper in your syrup pan means your less likely to give yourself a heart attack! You'll get it dialed in, just change one thing at a time so you what works and what doesn't.

[mspina14]

I don't have the answer to your dilemma but I do have to say your float looks home made and fantastic. I would like to get the materials list to replicate that. Great work!

Thank you.

But I can't take the credit. The float box, and all the pans and arch were made by Bill Mason.

As has been said on this site many times by many others, he does excellent work, at a reasonable price.

Mark

[maple flats]

It seems something is retarding the flow into the syrup pan. On my raised flue I keep it at 3/4-1" deep and I use an auto draw. Mine never gets even close to being just 1/4" deep during a draw. What is restricting the flow between the pans. While I draw my level falls about 1/4" (not to 1/4") by the time the float increases the flow. do you have a valve between the 2 other than the float valve? Are your pans level both side to side and front to back?
My auto draw when opens with my regulator ball valve in it's normal position, I get about 1 qt/minute flow out the valve. I have 4 channels in my syrup pan so it takes a while before the float reacts but I don't lose enough to get to 1/4" depth in any channel. At any rate, increase your depth until you can solve the issue.
You should not need to adjust to draw off.

[Super Sapper]

I agree that you need to run deeper in the syrup pan.

[Maple4444]

I definitely agree with Dave. Increase the depth in your syrup pan. I actually run at one and three quarter inches since adding a preheater and using RO. I do not want to burn pans again.

[mellondome]

How much bubble rise are you getting? You may actually be running less in the pan than you think if you are gettig bubble / foam rise.
For the float... leader also uses the same float as well.

[mspina14]

Thanks for the advise and support.

I can breath again now ;)

Below is the result of my latest handiwork:

16227

Looks like it's time to go to Walmart and buy some vinegar :lol:

I don't think anything is restricting the flow of sap from the flue pan to the syrup pan. I think I was probably trying to run the depth too low in the syrup pan. I did have bubbles in the last channel when the density got close to syrup. I think this is normal. But perhaps I underestimate the depth of the sap at that point.

How do others gauge the level of the sap in their syrup pan during a boil when the density gets close to 67 brix? It's hard to see the bottom of the pan due to the color of the sap and the amount of steam that obscures the view.:confused:

I know the thermometer probe in my last syrup pan channel is about 3/4" off the bottom of the pan. So when I can see the top of the probe, I know I'm running too low.

thanks again.

mark

[Bruce L]

You should have your syrup level or close to the top of the hole beside your thermometer into your draw off box. You can then monitor the depth of your pan in your draw off box,if it is just slightly boiling through the hole you are fine,any lower and you are pushing your luck. Also,what about your foam level? If your pan is foaming up quite high you are using a lot of liquid that is no longer covering the bottom of your pan.

[mspina14]

You should have your syrup level or close to the top of the hole beside your thermometer into your draw off box. You can then monitor the depth of your pan in your draw off box,if it is just slightly boiling through the hole you are fine,any lower and you are pushing your luck. Also,what about your foam level? If your pan is foaming up quite high you are using a lot of liquid that is no longer covering the bottom of your pan.

Thank you.

I don't really have an issue with a lot of foam. I'm just trying to figure out a clear landmark on my syrup pan that I can use as a reference point to determine sap depth in the pan.

Your point about using the draw-off hole as a reference for sap depth is a great idea. I can see this hole clearly, even in the thickest steam. I was boiling at a sap depth that was at about the middle of the hole. Clearly, too low :rolleyes:

Just so I'm clear, you're talking about this draw-off hole in the corner of the syrup pan, right?:

16228

The top of the hole is about 1 7/8 inches above the floor of the syrup pan.

I should keep the sap in the syrup pan at about this level?

thanks

Mark

[BAP]

Are you closing the manual shut off valve between the two pans while boiling? If so you should have it wide open when boiling and let the float control the flow. Also if you haven't already, I would disassemble the pipe and valve between the pans to make sure there isn't anything causing the flow between pans to be slowed down. I have seen chunks of niter break off and cause restrictions in the plumbing between pans.

[Bricklayer]

I have a similar pan setup and I moved up to 1 1/2" this year. Way less stressful. Last year I had a similar issue and I increased the size of my feed line to my float box to 1". Seems to react quicker.
I have an auto draw this year but when I was just cracking the valve drawing off last year I would open it real fast to get a quick blast of syrup through the valve and it would clear the nitre out and get the float moving. Then real small stream after that. Gotta be real quick though. Too big of blast will empty the channel pretty quick.
Were you able to get the pan clean after burning it?

[mspina14]

Are you closing the manual shut off valve between the two pans while boiling? If so you should have it wide open when boiling and let the float control the flow. Also if you haven't already, I would disassemble the pipe and valve between the pans to make sure there isn't anything causing the flow between pans to be slowed down. I have seen chunks of niter break off and cause restrictions in the plumbing between pans.

Thanks.

I used to run the manual shut off valve between the flue and syrup pan 1/2 open. My gaskets on the float valve were not able to hold back the flow of sap from the flue to the syrup pan.

I recently got new gaskets that are thicker and seal better. So this weekend, I was running the boil with the manual valve wide open. I controlled the sap level in the syrup pan strictly by adjusting the flue pan-to-syrup pan float valve.

I will check the pipe and valve to make sure nothing is clogging it. But I really think my problem was running the sap depth too low. It didn't leave me any margin for error.

And as we well know, errors can happen in sugar making!

Mark

[Bruce L]

Thank you.

I don't really have an issue with a lot of foam. I'm just trying to figure out a clear landmark on my syrup pan that I can use as a reference point to determine sap depth in the pan.

Your point about using the draw-off hole as a reference for sap depth is a great idea. I can see this hole clearly, even in the thickest steam. I was boiling at a sap depth that was at about the middle of the hole. Clearly, too low :rolleyes:

Just so I'm clear, you're talking about this draw-off hole in the corner of the syrup pan, right?:

16228

The top of the hole is about 1 7/8 inches above the floor of the syrup pan.

I should keep the sap in the syrup pan at about this level?

thanks

Mark

Yes Mark,that is the hole that I was referring to. If you run your depth of pan right at the top of that hole or just slightly lower,it will give you a great level indicator,if the foam rises in your draw off box you are too shallow. When you are drawing off you can see the depth of your pan relative to that hole. Should you find it getting too shallow you can always shut your draw off off,throw in your emergency pail of sap,or with practice you will see the sap coming from your flue pan mixing,bringing your level up and temperature down. Did you get your pan cleaned up okay?

[mellondome]

No reason to run that deep. I run mine @3/4" with no issues and feed the flue pan with 20%. If you have a rise in the bubbles , sap will not flow into the area because the level is higher than where it is comming from... leaving you with smoke and black syrup. I would suspect that you are making syrup in the channel before and as it gets to the end of the final channel, it is already beyond syrup and due to surface tension of the bubbles, it looks like your levels are ok... but if the heat went out you would find only a small fraction of the amount of syrup is really in the pan there. You may want to draw off early on the first draws to get the syrup out of the next to last channel before you have a run away boil.
When you get past syrup... the only way to fix the issue is to put fluid in the location with the problem. Holding a float down that is 8ft away ( 2x2 pan with 4 channels) will not help. Its like putting water on the neighbors house to put out the fire on your own house.

Also, use a hydrometer. If you are using the electronic brix meter to test to know then to draw, your pans will burn before you get a reading... and with hot syrup that reading isnt as accurate due to evaporation of your sample while you are waiting for the temp to adjust and the unit to read the sample.

[maple flats]

Actually you should have bubbles but not foam in the syrup pan. The weight of the foam can affect the depth. If that is the issue, use more defoamer in the flue pan at that pan's inlet. I went with an automatic defoamer dripper this year and it helped me use less while still controlling foam.
If your float valve will not control the level, get a new packing for it, you do not want to have the valve between the pans closed during operation.

[Sugarmaker]

One other point I may have missed? When are you closing the valve on the draw off? Maybe a different way to ask is when do you know your not drawing syrup any more?
Based on what you have said and shown. I would run 1.5 inches deep for a while till you get things dialed in.
Regards,
Chris

[Spanielslovesappin]

Float sealing issues will drive this whole problem.

If the syrup pan float does not seal off the flow from the back pan then the level increases so you adjust the float to put more pressure on the gasket to stop the level from increasing BUT as the pan level reduces the level will now have to drop farther to get the float to re-open. So you adjust the float again to allow more flow and the cycle repeats.

I think i would play with the levels on a cold evaporator with water.

Fill the back pan and then syrup pan via the floats; at what level does the flow stop? or does the flow ever stop? if the flow is not stopped than adjust the arm/gasket/spout to get a positive seal.

then slowly draw water, How far does the front pan drop before the float allows flow into it? does the level in the back pan also respond or is it dropping to low?

What effect does the draw have on the level across your syrup pan? An out of level evaporator can cause burn pans when running at 3/4".

This will give you a better feel for how your evaporator reacts.

You should not have to throttle in on valves prior to the floats ever!

[mspina14]

Thanks to all for the great advice.

To clarify, I was running the syrup pan at about 3/4" depth. The manual valve before the syrup pan float box was wide open. Sap was flowing continuously (slowly) from the flue pan into the float box and into the syrup pan. I had adjusted the float box so the flow was roughly equal to the evaporation of sap in the syrup pan. So the sap in the syrup pan was staying at 3/4" and the density was increasing.

I will be running it now at 1 1/2" to 2" until I get a better feel for the evaporator.

Pan will be soaking this week in white vinegar. I will try and clean it up next weekend.

Mark

[Sugarmaker]

And from what your saying you should not have burned the pan? The sap entering should have been more than you were drawing off? When did you stop drawing off? Syrup temps falling off or syrup density decreasing?
Point is that either you had less syrup than you thought or you were drawing faster than the sap coming in? How much syrup did you draw off at one time? Just trying to help. Burning the pan is no fun!
Regards,
Chris

[mellondome]

How well did you get the pan cleaned from the first scorch?

[mspina14]

And from what your saying you should not have burned the pan? The sap entering should have been more than you were drawing off? When did you stop drawing off? Syrup temps falling off or syrup density decreasing?
Point is that either you had less syrup than you thought or you were drawing faster than the sap coming in? How much syrup did you draw off at one time? Just trying to help. Burning the pan is no fun!
Regards,
Chris

Thanks Chris.

I was drawing off very slowly, maybe a stream of syrup equal to a pencil lead thickness out of the draw-off valve. I started the draw when the temperature was about 220 degrees (the boiling point of syrup that day) and the density was 67 brix (based on my refractometer reading).

I was monitoring the temperature of the syrup and was going to close the draw off valve when the temperature got below 218 degrees. I drew-off maybe a pint of syrup before the temperature hit 218. At that point, the pan started to smoke. I grabbed a nearby bucket of water and poured some into the syrup channel. From what I could see between the smoke and steam, there wasn't much sap in the front syrup channel, and whatever was in there was burning. It smelled bad.

I had read on this forum that some sugar makers are able to draw-off syrup slow enough once the pan is sweetened, that the amount of sap entering the syrup pan is equal to the amount of sap being evaporated and syrup being drawn-off. I have read where some are able to draw-off syrup for 30 minutes or longer until the temperature/density of the sap drops below syrup.

Clearly, I'm not at that point yet in my syrup making abilities. But I will keep trying.

Also, I suspected a continuous draw-off is easier on a larger rig than on my 2x4 hobby rig.

Mark

[wnybassman]

Thanks Chris.

I was drawing off very slowly, maybe a stream of syrup equal to a pencil lead thickness out of the draw-off valve. I started the draw when the temperature was about 220 degrees (the boiling point of syrup that day) and the density was 67 brix (based on my refractometer reading).

I was monitoring the temperature of the syrup and was going to close the draw off valve when the temperature got below 218 degrees. I drew-off maybe a pint of syrup before the temperature hit 218. At that point, the pan started to smoke. I grabbed a nearby bucket of water and poured some into the syrup channel. From what I could see between the smoke and steam, there wasn't much sap in the front syrup channel, and whatever was in there was burning. It smelled bad.

I had read on this forum that some sugar makers are able to draw-off syrup slow enough once the pan is sweetened, that the amount of sap entering the syrup pan is equal to the amount of sap being evaporated and syrup being drawn-off. I have read where some are able to draw-off syrup for 30 minutes or longer until the temperature/density of the sap drops below syrup.

Clearly, I'm not at that point yet in my syrup making abilities. But I will keep trying.

Also, I suspected a continuous draw-off is easier on a larger rig than on my 2x4 hobby rig.

Mark

I am able to get nice long draws on my 18x60, many times 20-30 minutes and up to about a gallon. On the contrary, I could also open my draw-off valve wide open without worry of the syrup pan float box keeping up.

I am trying to figure out how/why you are burning things only by drawing off extremely slow.

I usually start a draw when temp hits 8 degrees over, temp rises to 9 or 9.5 over, then settles back to about 6.5 when I stop the draw. While finishing and bottling today, I had two different stock pots with three gallons each that I brought back to a boil and they were right at syrup without any adjustments. My procedure seems to be working for me.

[Sugarmaker]

Mark,
You did good saving the pan! Even experienced sugarmakers can scorch a pan. Let me ask this, was there sap coming in the front pan through the valve at all times during the boil? It should have some sap coming in all the time, at least at the rate your boiling off. If not then you have a float setting issue. I kind of agree with setting the float cold (flow testing) but have never tried that.
A pint of drawn off syrup should not have burned the pan. But it did, so something did not go as planned. I think it went over temp faster than you think? 220 F is a little high? unless your thermometer is out a couple degrees. I usually make syrup around 217 F. (water boils about 210 F here)
May have reduced the volume faster than to thought and scorched a high spot on the pan???? Check again for rig being level (with sap).
You may have actually been drawing off too slow? You might have a pint that needs to be drawn off in maybe 30 seconds and then stop drawing, till the next (batch) is ready.
Medium rigs still do controlled batches of syrup. Big rigs with high concentrate sap can do continuous draws for quite a while.
Regards,
Chris

[mellondome]

Some info is missing in this whole thing. What is going with the channel before the last one when the burns take place? Also, thich way on the evaporator do your channels run?

On my 2x6, I draw constantly all boil. There maybe one or two times a boil that it stops. Pans @3/4 in. Drawing 10+gallons of syrup an hour.

[mspina14]

Mark,
You did good saving the pan! Even experienced sugarmakers can scorch a pan. Let me ask this, was there sap coming in the front pan through the valve at all times during the boil? It should have some sap coming in all the time, at least at the rate your boiling off. If not then you have a float setting issue. I kind of agree with setting the float cold (flow testing) but have never tried that.
A pint of drawn off syrup should not have burned the pan. But it did, so something did not go as planned. I think it went over temp faster than you think? 220 F is a little high? unless your thermometer is out a couple degrees. I usually make syrup around 217 F. (water boils about 210 F here)
May have reduced the volume faster than to thought and scorched a high spot on the pan???? Check again for rig being level (with sap).
You may have actually been drawing off too slow? You might have a pint that needs to be drawn off in maybe 30 seconds and then stop drawing, till the next (batch) is ready.
Medium rigs still do controlled batches of syrup. Big rigs with high concentrate sap can do continuous draws for quite a while.
Regards,
Chris

Thanks Chris.

I use the Saptapapp to find our what the boiling point of syrup is the day I do a boil. On the day I burned the pan, it said the boiling point of syrup in my area was 219.98 degrees.

I had sap continuously flowing from my flue pan into the syrup pan at all times. It was not a high flow rate, but enough to keep the sap depth at 3/4" at a boiling rate of about 20 GPH. I started the boil that day with a clean evaporator. I hadn't had enough sap for about 10 days to boil because of the cold snap. But yesterday, I started with about 100 gallons of sap. I boiled for about 4 1/2 hours and continuously had sap following from the head tank into the flue pan, and from the flue pan into the syrup pan.

My evaporator is perfectly level from front to back and side to side.

I probably should have started drawing off before the sap got to 220, but that is when my refractometer said the sap was at 67 brix. But i probably should have started drawing off at 218 or 219 when the sap was at about 63-64 brix.

Mark

[mspina14]

I am able to get nice long draws on my 18x60, many times 20-30 minutes and up to about a gallon. On the contrary, I could also open my draw-off valve wide open without worry of the syrup pan float box keeping up.

I am trying to figure out how/why you are burning things only by drawing off extremely slow.

I usually start a draw when temp hits 8 degrees over, temp rises to 9 or 9.5 over, then settles back to about 6.5 when I stop the draw. While finishing and bottling today, I had two different stock pots with three gallons each that I brought back to a boil and they were right at syrup without any adjustments. My procedure seems to be working for me.

That's exactly what I was trying to do on my rig. Sweeten the pan and then have a long, slow draw-off of syrup.

But I don't think I could ever fully open my draw off valve when the sap is at syrup density. All the sap in the front syrup channel would exit the evaporator in a few seconds and I don't think the fresh sap coming in could keep up with the flow to replace it.

Mark

[mspina14]

Some info is missing in this whole thing. What is going with the channel before the last one when the burns take place? Also, thich way on the evaporator do your channels run?

On my 2x6, I draw constantly all boil. There maybe one or two times a boil that it stops. Pans @3/4 in. Drawing 10+gallons of syrup an hour.

Here's a photo of my rig:

16231

The syrup pan has 3 channels that run side to side.

Here's a photo of the gradient I had developed as I tried to sweeten the pan:

16232

I check the density in the middle channel every so often, just to make sure I'm not making syrup in that channel. Yesterday when I burned the pan, the density of the sap in the middle channel was 10-15 brix below the density of the sap in the last channel.

I'm pretty certain I was only making syrup in the last channel. You can see in the last channel I was only running the sap depth about half way up the draw-off hole in the corner of the syrup pan.

Just was running it too shallow.

Mark

[wnybassman]

That's exactly what I was trying to do on my rig. Sweeten the pan and then have a long, slow draw-off of syrup.

But I don't think I could ever fully open my draw off valve when the sap is at syrup density. All the sap in the front syrup channel would exit the evaporator in a few seconds and I don't think the fresh sap coming in could keep up with the flow to replace it.

Mark

With a tiny pencil lead draw off, you shouldn't notice a depth change at all though. I monitor my depth by where the syrup intersects the angling temp probe in the draw off box. I run probably around a 1 1/2" depth, and only that deep because my temp probe seems to be more accurate submersed that far. Less depth and my temp gets flaky. But even a depth change of a 1/4" changes that intersection point I keep an eye on drastically. The only time my depth changes is when it gets a little deeper because my float sticks. I've got in a habit of wiggling it every 5 to 10 minutes so that doesn't happen though.

[Spanielslovesappin]

For sure you are running to shallow with your set up untill you figgure out whats is going on.

Assuming the bottom of the front pan float box is level with the front pan from your photos?

Possible that at 3/4" depth your float is not able to open much at all i.e. the clearance between the bottom of the float and the bottom of the float box at 3/4" is not very much. To test this with the float set to maintain 3/4" push the float down till it contacts the bottom of the float box, this is the available travel of the float, if sap is not gushing in at a high rate then your float just cant keep up.

Perhaps this float set up just cant run your pans at 3/4" or perhaps you have an issue with the z-arm and gasket that is causing you to have to over tighten the float to keep the level from getting to high which will then limit the amount and at what level it can truly re-open.

Again playing with this with water and a cold evaporator will really let you see what your floats can do without destroying your pans.

You should not have to tamper with the floats during a draw.

[mellondome]

Do you check for density anywhere else in your pan? Being you were starting with clean pans and no sweet, if you are only checking for density @ your draw point, you ciuld habe syrup elsewhere in the front pan and not know it. This would explain why no sap pushed forward when you drew off. Until you have drawn off a couple times to establish a true gradient , dont rule out syrup in the middle of the pan.


Sorry. Didnt see your previous post.

[BAP]

When you draw off, are you drawing off a hydrometer cup full of syrup and testing it to see if it is done before opening the valve into your draw off pail? If so draw off a cup, dump back into the pan then test the second one. A lot of times the syrup in the draw off box will have cooled a little and not be quite syrup but there will be a lot of syrup right behind it. Also, don't trust some phone app to tell you when your syrup done. Trust your hydrometer to check when your syrup is done.

[Homestead Maple]

I can remember going to a boiling seminar that was held at one of the well known maple equipment suppliers and he told the audience that "you become a real sugar maker when you can run your pans at a 1/4" depth". If he got many people to believe that I'm sure he sold a lot of evaporator pans!