Pre heater modification

[Parker]

Hey everyone-
I have a 4x12 evap that I will be setting up this summer and I want it to as fast as possible...When I bought the evap. it came with a 2x4 Small Bros. pre heater. this preheater has one continuos run of copper pipes in it with no manifolds and a hood that is about 4 inches over the top of the pan,,When I ran this evap in the past the preheater helped a whole lot and made a small ammount of hot water..Yesterday I was given a home made preheater that was used on a 4x8 flue pan and when I saw it in opperation 2 years ago it made more hot water and heated the sap up more than the small bros,,the home made one is 4 feet wide, 6 feet long, and 3 feet tall,,the sap runs into a manifold then tru 8 pipes into a manifold on the other side, with a little modifacation I think I can fit both of them on my sap pan..my question is #1do you think there will be problems getting the sap thru 2 diffrent sets of copper pipes (Vaporlocking)#2 how much head pressure do you think Ill need to do this,,#3 My flue pan is not set up for sight tubes and with a full hood how do you tell where the sap is in the pan,,sepratley neither pre heater coverd the whole pan...thanks in advance ,, Parker

[Brian]

Parker, if you have a float box on the side of your flue pan you can check the sap level by the depth in the float box. :lol:

[WF MASON]

I think going through both preheaters with different size pipes will give you a problem , there is such a thing as to much preheating and it boils and steams in side the pipes.I'd use the larger of the two and also put a site glass on both sides of the flue pan.

[WESTVIRGINIAMAPLER]

Parker,

You could have someone to put stainless sleeves on both sides of the flue pan and buy a set of sight tubes and it should work good.

As far as the preheater, the larger preheater should be plenty for what you need and should work good.

[strange syrup]

Parker, I run a 40x14 ss drop king with about 50' of 3/4" copper tubing in a coil, in the steam stack. Under the stream stack there is a ss pan hanging by wire with a 3/8 copper line running out to the side of the hood(which is a home built plastic hood) and it has a steady stream coming out of it. I keep 5gal buckets near and fill them with the very hot distilled water that is used for every thing from washing filters(in an old ringer washer) to sap tanks, or even the floor, (keep a cold bucket of water close if you should burn your hand).

The supply tank is about 10' above the floor, and has very good pressure at the float box, with a sap temp of (very) hot..

Don't know if that helps but it works here.

keep tring, thats were the FUN is..

[saphead]

I like the idea of a coil in the steam stack with a small drip pan, less interference with steam movement in the hood! Do you use a damper in the stack? What is the outlet temp. of the sap?

Saphead; No I don't us a damper in the steam stack, with the hood system that I us a damper will not work be cause the hood is a soft sided hood made with two layers of plastic (works very well for my operation.

As far as the sap temp going in, I cannot answer that, never put a temp gage on it, I tryed to keep the sap as cold as I can in the in ground tanks that I have be for I boil it. The sap going into the float box is hot enough that you can not hold your hand on the copper line feeding the sap float.
The feed rate is about 100-120 gph, so its getting through.

Please note that I have two 3/4" unions, one on the cold in feed just out side the steam stack, and the other is above the drip pan so the any water running down the pipe will drip in to the drip pan, also this allows easy removel of the steam stack,cleaning and any service work that could be needed.

keep reading and learning , its fun.........

Saphead; No I don't us a damper in the steam stack, with the hood system that I us a damper will not work be cause the hood is a soft sided hood made with two layers of plastic (works very well for my operation.

As far as the sap temp going in, I cannot answer that, never put a temp gage on it, I tryed to keep the sap as cold as I can in the in ground tanks that I have be for I boil it. The sap going into the float box is hot enough that you can not hold your hand on the copper line feeding the sap float.
The feed rate is about 100-120 gph, so its getting through.

Please note that I have two 3/4" unions, one on the cold in feed just out side the steam stack, and the other is above the drip pan so the any water running down the pipe will drip in to the drip pan, also this allows easy removel of the steam stack,cleaning and any service work that could be needed.

keep reading and learning , its fun.........

[strange syrup"]Saphead; No I don't us a damper in the steam stack, with the hood system that I us a damper will not work be cause the hood is a soft sided hood made with two layers of plastic (works very well for my operation.

As far as the sap temp going in, I cannot answer that, never put a temp gage on it, I tryed to keep the sap as cold as I can in the in ground tanks that I have be for I boil it. The sap going into the float box is hot enough that you can not hold your hand on the copper line feeding the sap float.
The feed rate is about 100-120 gph, so its getting through.

Please note that I have two 3/4" unions, one on the cold in feed just out side the steam stack, and the other is above the drip pan so the any water running down the pipe will drip in to the drip pan, also this allows easy removel of the steam stack,cleaning and any service work that could be needed.

keep reading and learning , its fun.........[/quote]

[q]

[WF MASON]

I've never heard of putting the preheater pipe inside the steam stack , but I guess it would work , how do you hold the tubing inside the stack ?? and is it uncoiled alot or left in the tight coil.??

[mapleman3]

Thats all well and good as long as you have the feed tank that much higher than the evap float box., I'll only have about 1.5 ft above, just enough for a regular preheater. I like the idea though.

[WESTVIRGINIAMAPLER]

Jim,

Are you going to build a parallel flow or a continuous sequence preheater??

[mapleman3]

I may do the parallell not sure. going to read up on it more.

[strange syrup]

WF Mason, Mapleman 3;
The steam stack is 18"ss, 3' sections with the first section holding the coil, the coil is held in place by two bolts that go through the horizonal center of the stack. The coil is kept close together and finished about 31/2' so it is a little longer then the section of pipe, this was not a big deal because it gives me room to hook up the line to the float box. and I also get 100%drain from the coil.

The top of the coil is only about 51/2' above the float box with the holding tank about 10' up from the floor, so the top of the coil to the bottom of the supply tank is about 18".

With the supply tank up in the rafters (that I built to hold the load) and I have a post to help hold the load too, the system would work even with a side wall of 8'.

With the coil in the stack, all the steam leaving the evaperator must pass the coil so that the in coming sap is at steam temp at the float box.....


We keep reading and learning and having FUN........

[WESTVIRGINIAMAPLER]

I have to say I am really impressed with the idea. I think more people might adapt it if they could get there sap supply as high as you, but most don't have that luxury. :D :D

Brandon; I don't see why if you have a 8' side wall in your sap house, why this system would not work. The problem is, the size of the steam stack, it needs to be large enough for the coil. Maybe with the right coiler you could make the coil small enough to fit a smaller steam stack.

waiting for spring and more idea's......

[strange syrup]

above post

[Parker]

That coil Idea sounds good,,I know on Bobs Pre heater (old style) the sap pan has a low, flat aluminum cover and all the steam goes out thru the rear ditch side just above the sap pan and there is a coil with a collection box under it, the coil is not over the pan with this type of set up,,,,,just off to the side a bit ,,I would think it would not be a efficent as a roof type hood where the condensate can run down the side and into a drip tray around the base of the hood,,I bet with the flat hood a lot of the condensate drips right back into the pan??? Ideas??? Parker

[Parker]

I was just thinking,,I know a fellow a couple of towns over that has an oil fired 4x12 and he has a sap coil in his smoke stack,,,,He Marty,,on you preheater does the vent pipe extend above the level of your sap in your holdind tanks??Seems like it must??? Parker

[strange syrup]

Parker;
I do remember that stile of hood configuration and I do remember somthing that they did return a far amount of water back into the evaperator, (I don't thing that they even offer that hood any more) but even with that hood, all steam that is leaving the pans would still pass the coils thus heating the in coming sap.
If Bob could eather of two things,first would be to insulate the hood so that the cool air from the sap house does not touch the hood cooling it, (keeping the hood hotter alows more steam vapor to leave).
The second idea would be REPLACE the hood system (if possable)
with the more standard hood system, this allows water a chance to flow down to the side of the hood and out of the pans.
With my plastic hood system, when the lights are on inside and the openings are closed I can still see water drops running down the sides and out, more so when a side currtin was open.
As far as having a coil in the smoke stack, it may work with an oil fired system (I don't know just my thoughts) that a shorter coil should be used because of the heet levels being higher. I did try it a couple of times in a 3x9 flat pan (that is still used at times) I ran a 1/2" line though the stack, but the flow rate was to low and it would vapor lock(THIS IS BAD) I think do to too much FIRE going up the stack,not heat.
I tried a short coil around the stack and then put some high temp insulation over it, this to would vapor lock but less often, the current system is a heet box, the stack is 10" going out, 14"section around that with the coil between them, this works with out vapor locking, this is an out side pan with out a hood...
As far as a vent pipe,,,don't have one on it, works very well with out one. I have about 6-7' head pressure (bottom of feed tank to float box) in the 20+yrs its worked fine.

THINGS I'VE TRYED AND MY THOUGHTS

STILL HAVING FUN AND LEARNING!!!!!!!!!!!!!!!!!!

[WF MASON]

I have seen quite a few flat type hoods with the preheater on the side , they don't drip condensate back in the pan becouse the hood gets heated , really hot and the condensate does'nt stick , the steam goes up the side stack, the steam does'nt care which direction it goes, up or to the side and up. The ones I've seen work well. The counter argument would be , I'm not sure they make the flat hoods any more. Or atleast the newest one I've seen was ten years old. So why would they stop making them?

[WESTVIRGINIAMAPLER]

If I make a continous sequence preheater, do I need a vent pipe on it to prevent vapor lock???

[WF MASON]

It does'nt matter what type of preheater you have , you need to put a 'tee' before the floatbox and vent the hot air out , I've used both , parallel and continous flow , the advantage I see with the parallel is becouse there is a box manafold on each end , a nipple or couplin can be added, then a valve pointing down into the flue pan to drain the system completely. With the continous , elbows are used and it can't be drained completely.

[WESTVIRGINIAMAPLER]

Bill,

Thanks for the tip, I never thought of that and I might take that into consideration. Do you have a preference or which one do you think works the best??

At the "tee" before the float box what do you put on the tee? My mind is not working right. If it is just a tee won't the sap run out !!!!! Do you run a vent pipe up somewhere?

[WF MASON]

The Tee is a 1'' feeding the float , you reduce off it to 1/2'' ridge copper going straight up as high as your feed tank, the 1/2'' will burp as the hot air escapes.

[Breezy Lane Sugarworks]

To be even fancy with the burp line, you gould run it right back into your feed tank. I was talking to a guy that has one and he said that the line not only lets the air out, but it also burps out a little liguid. So if it is right back into your tank then it won't make a mess all over.

[WF MASON]

A very good idea , I always told people , 'don't stand under the pipe'.

[WESTVIRGINIAMAPLER]

How high does the vent pipe need to be?? If my tank is full, the top of liquid is close to 70" above the float box.

Does it need to be that high or could you run like a small 1/4" piece of tubing and bend it over where it would drain out in the float box??

[brookledge]

I use a piece of 1/2 " black plastic to run up for the vent. a scrap piece doesn't cost anthing if you dont't go back to the feed tank just make sure that you are higher than the feed tank. the idea of running back to the feed tank sounds the best because it will almost always burp sap out. If you run the vent pipe to your float box you could create a syphone through your vent pipe that would by-pass your float causing a mess.

There is a lot of talk about "vent pipes" my question is how high are the feed tanks suppling the float box? My feed box is about 7-8' above the float box and "NO VENT PIPE". I have a 3/4 copper line fr the feed going into steam stack, coiled, then droping to the float box value. The system has ran 24-7 and no vapor lock????

With a vent pipe system are the Feed tanks lower? Flow rate lower? Just some question that I have.

JUST THINKING ABOUT WHAT I'M READING.............

[strange syrup]

above reply

[brookledge]

the theory behind the vent pipe is to allow any vapors to escape. If your float was not calling for any sap, the flow is then not moving which can lead to boiling inside the pre-heater. think of it like a tea pot when it boils it vents out the top. As far as the height of the feed tank it has no bearing. what ever ht. you want. and it has no effect on the flow rate. Some times if it is to high it will put to much pressure on the float and leak by.Mine is 1 1/2" supply line 140 gpm. If you buy a pre-heater the manufacturers will size the pre-heater to the size of your arch. If you make your own you need to try and size accordingly to get the sap as hot as possible with out boiling. If the pre-heater is not big enough you can't get the sap to around 200 ish and it will slow down the boiling in the flue pan where it enters. Idealy 210 degrees coming out the pre-heater is good

[WF MASON]

A friend of mine is going to make a paralle flow preheater and is going to try making the manifold on each end out of copper tee fittings , and cutting back the shoulder on each side of each tee so you have the minimum width and shoulder to solder to.The reason for doing the cutting is to keep the preheater to a smaller compact size , using the same amount of heating pipe in less space. On the ends of the low side manifold you can pipe the inlet and on the other end put your elbow with drain valve. If the tees work , it would make building a paralle flow preheater something about anyone could do.
I have seen this done on continous flow preheaters where the elbows are made of street 90' fittings , the st's are cut down so your soldering 1/8'' or so instead of 1 1/2''. Same reason , compact.