pre heat idea

[dave gagne]

hi, i am new at this but i came up with an idea to pre heat. let me know what you think. i have my top bucket of about 15 gallons , after 3 hrs at approx. 158* , is this worth doing or not i am using a half pint evaporator. ****sorry attempting to add picture so quetion will be understood.

[KenWP]

Anything that heats sap warmer then it was is a good idea. Some just work better then others. If sap is 40 degrees and you get it to 50 degrees thats 10 degrees your not taking out of the evaporator.

[Woodland Acres]

I was wondering if anyone ever tried to use a tankless water heater to preheat with.I dont know if they would work on gravity flow coming out of your feed tank to your evaporator.

[Haynes Forest Products]

You could but its all about saving money to recoup the wasted heat from the arch. Now you could set up another evap at your buddies house and then when the sap is almost syrup bring it over to your house and that would be a preheater:lol: But seriously just chuck the wood in and try and heat the sap with the throw away heat that is the Idea.

[Peepers]

Saving wood is one factor for me but the other reason I am looking at building a preheater this year is saving time. Every time I put almost freezing sap into my pan it really knocks down the evaporation until it gets back to boiling. I suppose a simple slow feed of cold sap would help instead of me dumping a bunch of cold sap in but a slow feed of hot sap would be even better in order to keep the boil going and keep the evaporation rate as high as I can get it.

I think for the money of a tankless hot water heater you could probably invest in an RO system that would shortcut your boiling even more. unless you can get a tankless H20 heater for free in which case give it a shot and let us know how it goes! :)

[KenWP]

How are you going to heat the tankless water heater. If you could find the coil out of one and use it for part of the stack it would work most likely. It would use up all the heat from the stack and would give you some pretty hot sap.

[Woodland Acres]

Tankless water heaters run on either electric or propane.

[BarrelBoiler]

aren't we building "tankless" sap heaters with our preheat coils,etc;)

[Haynes Forest Products]

You can get a cheap tankless heater at Grainger but there elec and have a heating element so conversion is hard.

[sponge]

the small tankless water heaters are not the best. I installed 2 of them at work and they only raise the temp 35 to 45 degrees above incoming temp witch sounds pretty good for sap but that was 240v and 30 amps witch isn't going to look so pretty on your electric bill. needless to say we removed them less than a month later and installed a tank heater. good luck

[trackerguy]

Dave,

Whatever you do to use steam to heat incoming sap will work, just remember not to let the condensate drip back into your boil or it will actually decrease your efficiency.

[jayburd73]

That is an idea i was thinking of also. My crown oil boiler in my house has a tankless coil in it that comes out with 8 bolts. when i bought it the coil was a $100 option you could install it in your stack easy. I have a 40 gallon stainless tank that is jacketed that I'm going to use as a feed tank. I thought of using a circulater pump and a coil like that one to pump hot water through the tank to preheat sap. I will try it if I come across a free pump and just use tubing on the stack for heat. My goal is to get some evaporation out of the tank.I will use a expantion pipe and vent it through the roof like my open system wood master outdoor boiler.

[hymer02]

I have an outside wood stove that I heat my shop and home with.I tried something similar to your setup.I took a barrel and mounted a 25' coil inside with a bulkhead fitting on the bottom.I then built an elevated shelf for the 35 gallon barrel to sit on.That way I can regulate the sap flow into the preheat pan.I split my shop circulator pump in/out leads with shutoff valves and plumbed to the barrel.I checked for leaks,then filled the barrel with water.After four hours it was 150 degrees.My boiler will heat to 175 so this should keep up with my boiling rate.I'm going to try to maintain the 35 gallons.Will try it out probably this weekend.Hope she works!

[maple sapper]

I have a preheater pan that sits over the stove pipe that exits my barrel stove. The more I am working on my syrup rig making syrup, the more efficient ideas I come up with. I have been pondering the idea of getting a 25 or 50 ft coil of 1/2" copper tubing and wrap it around my stack pipe around and around to warm sap before even entering the preheater. I bet that a 1000 deg stack temp may even create a boil in the piping.

[KenWP]

Thats a lot of 1/2 inch tubeing. If that dosn't get it hot nothing will. I found that a half dozen twists of 3/8 seemed to be almost enough. This year I have to go a bit more becasue of three times the boil rate hopefull. I did get a hold of a bunch of 7/16 copper but then found out the nobody carrys parts for it. I searched for months and finally found 3 7/16 to half inch couplers. Hopefully thats enough to plumb it in and out. I really could use a couple of Ts also but they don't exist.

[Lukie]

i have a barrel stove and did what you are talking about rapping the copper pipe around the stack and on one end i have a five gallon bucket of cold sap hanging and a vavle on the other end and it works great just dont rap to many coils around because it will get to hot and buy the time the sap gets to the pan it is burnt and if you turn the valve off it will boil sending steam back through the line when i am not useing the feed line i move the tubeing to the side and run five gallons of water through it and it cleans it out and then it can just set with notheing going threw it and dont rap the tubing close to the outlet of the stove its to hot

[adk1]

yeah, I ahve heard that too, you can acutally burn the sap in those stack coils. For these smaller evaporators that typically have the tank above the flue pan area (flat pan setup) that drips int othe pan, has anyone thought about usign a turkey fryer with propane to heat the sap, then add that into the sap preheater tank to allow to continuously drip? This should be pretty simple and those large turkey fryers can heat anythign up pretty darn quick.

[Toblerone]

After abandoning the idea of a coil wrapped around the stack a while ago due to boiling and scorching in the pipe, I am going to try splitting 20' of 1/4" into 15, 16" strips and making a radiator-type looking thing that I can press up against the flat part of the stack base. That way I can move it away from the stack easily if it starts to boil.

Anyway I was trying to calculate if it would be worth it at all and I came up with this formula. Since it takes 1 BTU to raise 1 pound of water 1°F and 970 BTU to change one pound of water to steam, the additional gallons per hour for a given temperature difference:

Current gal/hr * ΔT °F * 1 BTU/(lb °F) / 970 BTU/lb = extra gal/hr gained

I included all the units so you can see they all cancel properly. I am doing 16gal/hr right now, and if I can raise the sap 150°F then I'll boil an extra 16 *150 / 970 = 2.47 gal/hr. That feels worth it to me.. now I hope I can get 150 °F out of it!

[Harken]

Trackerguy...so are you saying that a pre-heater pan that sits on top of a half pint is a waste of energy ?? Is there a way to mount it so that the condensate doesn't run back into the pan ??

[adk1]

Harken, when I order my WF Mason 2x4 I am having Bill modify the preheater pan to be located up near the flue pipe, btu I also plan on adding sap to the preheater that is already warm using a turkey fryer pot etc.

[Toblerone]

The only way to extract meaningful heat from steam (not under pressure) is to condense it (970 BTU/lb). If that condensed water were allowed to go back into the sap pan, it will just need to be boiled off again (at 970 BTU/lb). So you would have been better off with putting the sap directly into the pan. In order to gain any heating, condensate must be prevented from re-entering the pans.

In any case, I doubt you will get any significant heating simply by having that preheater pan on top of the evaporator at all. There just isn't enough surface area to condense that much steam. That's why people build elaborate copper preheaters.