Preheater Design (revisisted)

[elmcreekmaple]

Here are a few pics of our preheater.

60 feet of 3/8" copper tubing wrapped around our 6" stack, then wrapped with a piece of 7" stack. I will stuff insulation around the top and bottom and maybe thermal wrap the copper coming out to drip into our pan. I will put a valve at the end.http://www.mapletrader.com/community/album.php?albumid=28&pictureid=176http://www.mapletrader.com/community/album.php?albumid=28&pictureid=177

If it don't get hot now, it never will!!

[70 Buick]

very cool
nice job

[Haynes Forest Products]

Good job NOW dont let sap cook and burn in the coil or you will be selling it as scrap. When the sap burns it will taint all new sap and you will be selling BBQ flavord syrup:mad: When the sap runs out you need to chase it with water to clean it. Now if it gets to hot it can boil and vapor lock so keep a close eye on it. Things can get ugly with a steam boiler so be careful with the valves:o

[crackher]

Nice.
I was going to do exactly the same thing. but I am a little worried about the whole vapor lock issue. I was wondering in an automatic valve at the inlet to the coil/exchanger would make a difference to release steam but not too sure. I ahve seen around here people putting a 'T' facing on a 45 upwards to releave the steam. The only diffence I was thinking about is making the shroud removeable along with te sulation so that when i need to start shutting it down I can remove the insulating shroud and cool it more quickly

[NH Maplemaker]

Best safe guard for vapor lock is a bypass valve above your coil from sap tank! A good size bucket of fresh sap be side your evaporator for the oh Sh** factor works good also!! JimL.

[crackher]

makes sense but how do you know when to open the bypass valve? without constantly looking at it

[NH Maplemaker]

Well when your boiling I'm sure you are watching your sap level in your pan. At least you should be! So you can monitor the sap coming out of the preheater pipe. If it stops flowing or start spitting steam and sap you are at or very close to vapor lock! at that point your first concern is to maintain sap to the pan so it doesn't burn. That's what the valve is for. It lets you Bypass the preheater by opening it!
As Haynes said if it stay vapor locked for to lone,sap will burn and give a burnt taste if allowed to go into the pan with good syrup! Hope this helps !Jim L.

[elmcreekmaple]

where could you get vapor lock? Maybe I am missing something but ours will be setup like this:

60 gal tank (lid off) to a tube gravity feed into our pre-heater with a valve at the spout to regulate flow. we are using 3/8" tubing and last year we were using a similar setup that would only get to about 150 deg with a trickle. I figured this new setup that I pictured above would be more efficient but no where near hot enough to get steam going. And even if it does, can't it travel up gradient thru the tubing and out into the tank? If need be we can bend the spout off into a bucket with water or run wide open.

Hope it works!

[Steam]

Elmcreek, no dought you will get some heat out of your set-up, but you'll have issues too. I had a similar set-up and it drove me nuts. Here is what I learned:
When starting to fire the evap, it takes a while for the pans to boil, so all that sap going through the coil is filling pans that are not boiling, and trust me, you need flow ALL THE TIME coming out the end of that coil. As far a vapor lock, it's not an issue as long as your sap feed to the coil is higher than the inlet of the coil. (with one end of your copper coil open it just can't vapor lock)
Just so you know...I ran it dry several times and then put sap back throught it. It shot out steam and then brown sap and then it was back to normal. Don't sweat it if it happens, you could divert it on the ground until it ran clear if it bothered you, by the way don't put your hand near the outlet of your coil after it went dry and you are putting sap to it......it's like a steam pressure washer!!! Watch out.
The pre-heater design I wish I did was to use the steam coming off the pans to pre-heat the sap...no burning issues and a good supply of hot water. There is a vast amount of energy that is there for the taking if you can get the steam to condense on a pipe/coil filled with sap. One important point here, once that steam condenses on that pipe/coil and starts dripping you need to keep it from going back into your pans. Sorry for rambling, have fun and hope I may have provided some insight.
Gregg

[ca2devri]

How did you wrap the copper so tightly? I'm having a heck of a time!

Chris