Copper Coil Preheater ,,,,Issue ????

[TerryEspo]

Good Morning All:

I did a small boil last eve.

My copper coil preheater works fine, but I am still getting used to adjusting the flow, learning.

Last night, I shut off the flow completely for about 10 mins to get my pan sap level lower.

When I opened the valve to let new sap enter from the head tank, it spit a bit,,,, then a bit of steam,,,, then........DISCOLORED sap,,,,rusty, or copper color, not exactly sure what hat was. Came out for 1 or 2 seconds then clear sap agin.

It went into my sap pan and I boiled it anyway.

End result, syrup is fine.

But what was that funny fluid that came out ?? Soot from sitting dry ??

I may reconcider a new type of preheater for my unit.

Terry

[jake22si]

probably burnt sap, the preheater doesn't just stop heating when you turn the valve off, you would need a constant flow to prevent it, maybe have it feed back to the sap bucket

[325abn]

I never leave sap in the preheat tube. If I need to turn off the feed flow I turn it off at the feed tank and this allows the feed line to drain. Dry copper is no problem.

[TerryEspo]

I do shut off at the feed tank.



But maybe there is a bit of sap that does not drain out of the copper tube entirely. This is the first time seeing that funny color. Maybe next boil I will keep a cup and after I shut it off I will catch the first sap coming out.

My copper tube is brand new this year and only has approx. 50 gallons run through it.

Burnt sap sounds probably right though.


Terry

[jrgagne99]

The sap will not drain if you only shut it off at the feed tank. You need to vent the top of the coil too, otherwise vapor lock prevents draining. Think of a drinking straw with trapped soda in it when you hold your finger on the top of the straw. I learned this the hard way one night, when the left-over sap in my coil froze solid, expanded, and deformed the coil so much that it didn't touch the stovepipe anymore. Needed to make a new coil, this time I put a vent valve on top.

[Ren]

Terry,I think you will want to have sap or water in the coil and flowing at all times when there is heat going up the stack. I am not sure why you would want to super heat the copper and then allow sap to enter it. There is always going to be a little moisture in there, even when drained. I am glad it didn't ruin your batch of syrup but I would not want to take the chance of adding burnt sap into the pan. I just let mine drip into a bucket till the float valve starts working.

[lpakiz]

I would suggest that the coil never stop flowing,at least a little. I used a diverter hose slipped onto the discharge end and directed over the side into a pail.

[Greg Freeze]

Like the rest have said, never stop the flow. Diverting into a bucket is a good idea if you need to stop flow into the pan. The more you use it, the better you'll be at contolling the flow. If I want to lower the pan level, I will shut the feed line down to the point that the sap coming out is almost boiling, but never shut it off. A couple things to remember are
-the faster you run the feed line has a direct relationship with how hot the sap coming out of it is
-this intern has to do with how fast your boil rate in your pan is
-if you need more flow but the sap is cooling down too much, you need to add on to the feed line coils around the stack or
-another thing you can do, is wrap aluminum foil around the feed line (5-7 layers), that will make your coils more efficient
After some experimenting, you'll get it set up. My philosophy is, I want the sap coming out of the feed line nearly boiling and I also want the flow when it's nearly boiling to nearly match my evaporation rate. Good Luck!

Greg

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[TerryEspo]

All really good ideas here.

I like the idea of a bucket off to the side to keep the drip/flow going.

Looks like the copper can stay with me a bit longer.


Terry

[PerryW]

I've had copper pipe turn my sap green before. I had a stainless 100 gallon oval tank with a 2" copper drain pipe coming off the bottom. The first gallon of sap would often come out green! Ugh! I replaced it with a plastic pipe.

[jrgagne99]

Like the rest have said, never stop the flow. Diverting into a bucket is a good idea if you need to stop flow into the pan. The more you use it, the better you'll be at contolling the flow. If I want to lower the pan level, I will shut the feed line down to the point that the sap coming out is almost boiling, but never shut it off. A couple things to remember are
-the faster you run the feed line has a direct relationship with how hot the sap coming out of it is
-this intern has to do with how fast your boil rate in your pan is
-if you need more flow but the sap is cooling down too much, you need to add on to the feed line coils around the stack or
-another thing you can do, is wrap aluminum foil around the feed line (5-7 layers), that will make your coils more efficient
After some experimenting, you'll get it set up. My philosophy is, I want the sap coming out of the feed line nearly boiling and I also want the flow when it's nearly boiling to nearly match my evaporation rate. Good Luck!

Greg

-

I second all of Greg's recommendations.

To insulate my coil, I use 6" water pipe insulation, then wrap the whole thing in aluminum to prevent the fibers from blowing off into the syrup.

Plus at the top of the coil, I use a shutoff valve vented to air which, after shutdown, allows me to fully drain the coil to avoid freezing.

Do you other copper-coil folks do this?

[sg5054]

I just removed my copper coil. I had taken single wall stove pipe and and covered the coil with it to insulate. It worked okay but not a good enough result plus the issue of the coil being heated continuously. I made a quick and dirty preheater out of 3/4 copper pipe. It goes across the width of my pan 3X at the front and then drains to the back of the pain. Immediate improvement and vigorous boiling in the the first section now! It just sits on top of the dividers. Took me about 30 minutes to build. I'm not catching the condensate at this time as I should but this was an experiment. I'll build a full size one this summer with drip trays.

[valleyman]

Hi Terry
Definitely burnt sap. My work around is as follows: I lift my sap feed line away from the rear pan until needed. I fill my pans with sap get a boil going. When enough evaporation has happened and it's time to add more sap via the coil, still keeping it away from the rear pan I open the valve. I open & close a few times to release steam and get a flow going and sure as shootin the sap gets cooked and comes out brown. Once clear I more the line to the rear pan and adjust flow. I also rigged up a strainer which adds a layer of filtering to the sap entering. See the attached photos.

7360
7361

[jrgagne99]

Valleyman, that seems like a bad idea to flow fresh sap through a copper coil that is interally scorched or burnt. Doesn't that impart an off-flavor to the syrup?

[valleyman]

jr,

I dont move the coil feed to the pans until its running crystal clear and no off taste in the finished syrup whatsoever. Generally the pans are boiling within an hour and I run additional fresh sap in for a couple hours more. No problems. I do like your idea of the vent valve. My coil is loose as well and doesn't heat the sap too much but I have it down where I can keep all 4 pans boiling with fresh sap streaming in at a good rate for my set up.

Maybe for next season I'll tweak it.

Thanks

[bowtie]

just spent $130 for new coil pre-heater, 50 ft flex copper,shark bite fittings, 2ft pc 8" pipe, rain collar, my wife was less than thrilled! anyhow i have made 15 tight wraps around a 6" pipe and plan to shroud it with the 8" pipe and put rain collar on outside to trap heat. my question is my head tank is 7'2" high, will i have enough head to push through consistently that many coils or am i going to have problems trapping some sap in there and then vapor locking? boy ,i hope this helps or my wife will , well it won't be good!!
i have a small 3 wrap coil that is leaking and i feel doesn't really do anything that is why i went with so many coils.

[Greg Freeze]

You'll be fine at that height. The only thing I would be careful of is those shark bites. If you get them too close to serious heat, I imagine you'll have problems with them. They seal with an o ring internally.

[325abn]

I have 40ft of 3/8 my feed tank is at 8ft and I have no issues with it pushing though. Make certain you have a vent between you feed tank and the stack.

I have not had any issues with burnt sap in mine. Yet! The only time I do not have sap moving in it is at start up and prior to the boil starting in the flue pan. It only taks about 5 - 8 minutes for me to get a rolling boil so maybe thats the key.

[valleyman]

Any photos out there on the copper tubing vent valves on your set ups?

Sounds like I should be adding one on my setup.

Thanks
-Greg

[sg5054]

I just removed my copper coil. I had taken single wall stove pipe and and covered the coil with it to insulate. It worked okay but not a good enough result plus the issue of the coil being heated continuously. I made a quick and dirty preheater out of 3/4 copper pipe. It goes across the width of my pan 3X at the front and then drains to the back of the pain. Immediate improvement and vigorous boiling in the the first section now! It just sits on top of the dividers. Took me about 30 minutes to build. I'm not catching the condensate at this time as I should but this was an experiment. I'll build a full size one this summer with drip trays.

Boiled for 4 1/2 hours last night. Definitely a better arrangement and no worries about over heating the tube. I have a 5 gallon float tank set at about 6' with a float valve installed. A 12v pump with a pressure switch keeps the tank filled, drawing from a 200 gallon tank outside behind the shack. I keep that buried in snow. Gravity drains the float tank and it is a steady down hill run to the evaporator. I don't have a vent installed because I don't have a valve at the float tank outlet. If any pressure builds it will push back into the tank and the 5 gallons is standing on the water column so it is self purging. When I had the coil it was set up the same way.
I have a cement board behind the stove and the supply line lays against that for a foot or so (it gets pretty warm) and then passes close by the stove pipe and on down to the preheater.