Preheater

[WESTVIRGINIAMAPLER]

When I make my preheater, I have read different places that they need a pressure release valve or something to that sort on them. Is this correct and where does it need to be??

Also, when it gets extremely cold, how do you keep the sap that is inside them from freezing and busting since it doesn't appear that they are designed to be drained all the time??

[mapleman3]

I have the instructions on building them I just have to remember to send them to you, it tells sizing, constructing them and using them and the different types.

[WESTVIRGINIAMAPLER]

Jeremy,

Wish I could put in some heat but the build I have it is is 30 x 60 and the front is partially open with no ceiling, so it would take something from nasa to heat that thing. The heat lamp idea sounds good, so I may try that.

[WESTVIRGINIAMAPLER]

Jim,

I really appreciate you sending me down instructions. Joe(mapleking) has given me some ideas and helped me some, but something is writing is much better!

Again, thanks a bunch! :D

[Fred Henderson]

I put a 1/4" bleeder valve at the low end of mine and as the same at the high end. If I think its going to freeze hard that night or go for 3or 4 days without running I close the main feed valve and open both bleeder, The lower one drains into the pan.

[WESTVIRGINIAMAPLER]

Are all the preheater pipes connected together at each end to where the sap intermixes are does each pipe connect to the other pipes one at a time if you know what I mean??

Jim I would also be nterested in the plans for the preheater or info on where to find them. I have the material for my hood but dont want to start it untill I figure out how big the preheater needs. Thanks

[wanabe]

Sorry Jim I didnt realize I wasnt logged in that reply was mine. Thanks Jeff

[michaelh05478]

My preheater has a 1.5" copper pipe going in and 1.5' comming out. It must have a couple of rows or so. My feed end has a 'T" on it sos i can take the plug out to drain it into the float...I dont think mine has a pressure relief valve, I havent seen one!!!!

[WESTVIRGINIAMAPLER]

I can't see what benefit a pressure relief valve would be unless you were running the evaporator without allowing any sap to come out of the preheater. The way my float system is designed, any steam should come out and the float box.

As far as it possibly freezing, I am thinking of using some time of forced air such as a compressor or blower to blow out the sap out of the preheater any time there is a chance it could freeze. Don't know if it will work, but seems to me like it would especially if the preheater was level. :?

[powerdub]

WMV

The sap should flow in one continuous run back and forth to achieve top optimum efficiency. If you run it into a manifold and down, say ten pipes to a manifold on the other end and out to your float box the sap is going to take the path of least resistance and not heat up that much. As for a vent, you should have one at the outlet of the preheater pipe. When you are preheating to 210 or better it will vapor lock on you and could take a couple of minutes to get it going again. I used a piercing valve for an ice maker with a small piece of eighth inch soft copper and leave a little stream coming out into the float box so there is always a little flow.

[WESTVIRGINIAMAPLER]

Scott,

Sounds like just the info I needed to now. I appreciate all of you that are more knowledgeable at things than I am helping me out.

I live the valve idea also and thanks a lot!

[WESTVIRGINIAMAPLER]

Does one end of the preheater need to be elevated or can it be level and if one end needs to be elevated, which end is it??

[guest]

I was wondering what kind of piping configuration should be used. It seems to me that a continuous flow setup would really cause havoc if it vapor locked. To me a manifold system seems better as I cant believe all the loops would vapor lock and you would still have a flow into your float box.Thanks for any input, as I am going to build a hood/preheater for next year too!!
John

[WESTVIRGINIAMAPLER]

As far as vapor lock, I guess I will know a lot more about it next year. I will run a slightly higher level in the evaporator next year and I am going to install sight glasses on my flue pan since I will have a hood. Since it is a drop flue, it keeps the close to the same level in the entire evaporator and I can monitor the level by the sight glasses.

If it vapor locks, I will push the float down and that should take care of the vapor lock.

I know on Bobs the pipes are 2" and it is one long run, No manifold, and no pressure reliefs or drains, if it will be getting really cold he will drain it but hasent heated or drained any thing this year,,Havent had any vaporlocking issuesyet that I am aware of but when we were burning the standing dead 4' red oak {the NITROMETHANE of sugarwood} the preheater would start to chirp and spit (mabey vaporlocking?) the feed into the float box was very,very hot...when were burning the wet pine it is not so hot {can hold your hand on it} Of course there is a 6 foot drop with 2" pipe from the holding tank into the preheater Parker

[WESTVIRGINIAMAPLER]

Last year I used a 3x7 flat pan and I had a good preheater on it. I had a 1/2" piece of copper tubing ran from the feed tank right through the middle of the arch almost all the way to the front. The sap was coming out it boiling hot and it made like a chirping sound. I think that sound has to do with the high temp of the sap when it gets close to boiling or to boiling.

Good preheater setup for backyarders and it worked great. Each day at the end of the day, I would unhook the tubing coming out of the feed tank and pour a quart of water through the tubing to flush out any sap to make sure it didn't scorch any sap anyside. If the water fully evaporated, it would hurt anything.

I used it all season and it worked great. I was having a steady stream of partially evaporatored sap running into the pan all the time! :) :D :D :D

[WESTVIRGINIAMAPLER]

I would think that for some of you that don't have a preheater and have a hood with a 1" drip channel around around the outside that you could run one run of 1" copper pipe all around the outside of the hood just above the drip channel and it would preheat the sap pretty good. It would be simple to make and the drip pan/channel is already in place. Besides the steam that would help heat it, you would have some hot condensation running on it also.

Don't know for certain it would work, but I can't see why it wouldn't. Even if you only gained 3 to 5 gallons an hour, that is a lot better than nothing.

[WESTVIRGINIAMAPLER]

I am going to make my preheater soon and I would like input from some of you that know more than I do. I am planning to make a continuous flow instead of a parallel flow and I would appreciate input on whether this is the best design or not.

What I mean by the parallel flow is that it has a manifold on both ends and the sap comes in one end of the manifold and flows uphill to the other manifold where the outlet is.

The continuous flow is one uninterrupted series of pipes where the sap comes in at the beginning of the pipe and goes out at the end!

Thanks for all the input in advance.

[WESTVIRGINIAMAPLER]

My the body of my preheater is finished if you would like to take a look at it on my website. It is just over 25' in length and this doesn't include the manifolds on each end. The raised pipe is for the incoming sap and it will flow down into the manifold with the valve on it. This will be the lowest end and allow me to drain the preheater after each boil. On the upper end, I have to soldered in pipes that run thru the hood and I have developed a quick connect/disconnect system that I think will work great and cost just a few bucks.

I bought 2 of the 2"long x 1.5" diameter connection hoses that Leader sells and I am going to solder 3/4" to 1.25" connections on the outgoing and incoming sap pipes. There will be 2 connections on each pipe with the 1.25" ends turned towards each other and the 1.5" leader connection hoses fit perfectly over the outside of the copper fittings. Two hose clamps on each pipe just outside the hood on both pipes and I think it will work great.

All the pipe and fittings in the preheater are 3/4" thin wall copper(I think it is called type L). The preheater is aprox 52" long x 12.5" wide.

Hope it works great, I think it will. You are welcome to give negative or positive feedback as you would like! :D :D

[Brian]

Brandon, it looks great. Are you going to have your pre-heater tilt back toward the stack with some kind of drain with a shield on the bottom? This would keep the moisture from dripping back in to the flue pan. The pre-heater I have has a piece of stainless with a V folded in it that lays on the bottom of the pre-heater with a copper pipe souldered on it to run out the back of the hood. It has 2 ss straps that go cross ways, 1 in the front and one in the back.They have holes drilled in them on each end also through the hood with ss bolts holding the shield in place. I hope this makes some sense.

[WESTVIRGINIAMAPLER]

Brian,

I have a stainless drip tray that integrates into the drip channel in the hood. It has brackets on it and are adjustable to adjust the grade of the preheater. The end with the valve on it will be the low end and the other end will be a couple of inches higher.

I will post pics of it in the drip pan sometime this weekend! :D

[Brian]

Great, sounds like you are all set!! :D

[mapleman3]

Brandon. it looks great, did any of the info I sent you help with the building of it? it seemed like good starting info. you'll be all set for hot water this year.. what a plus that will be, and think of how that boiling rate will go up!!!

[WESTVIRGINIAMAPLER]

Jim,

The plans you sent helped a lot, especially the more modern set of plans. It was a lot more simple and to the point. The second set was a little vague and seemed a lot older.

Thanks a ton for the help and I will be glad to make copies of these plans and send them to anyone else to help them. Sure is great info. :D :D

Brandon

[Maple Hill Sugarhouse]

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[WESTVIRGINIAMAPLER]

Kevin,

Thanks for the kind words. I am anxious to see if it works myself and it is only about 4 months for me, so the wait won't be long. I hope the temp will hit 150 degrees or better. With the inlet and outlet pipe lengths, I have about 27' of pipe not including 2' of mainifolds. This is well more than the amount of pipe specified for an evaporator my size. I went with the thin walled copper pipe, so this should help even more.

I bought a 1/4" inch needle needle valve that I am going to install outside of the hood and a 1 foot section of 1/4" copper tubing that I am going to run 7 or 8 inches high and bend it over into a "U" shape for a hot air/gas vent. If I am not having any problem, I can shut the valve off and if I need to vent it, I can vent the steam/water into the float box.

I would appreciate input on whether this idea will work before I install it onto my preheater?? :?

[Maple Hill Sugarhouse]

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[WESTVIRGINIAMAPLER]

Kevin,

I am glad to know that. I won't install it and if I need to, I can have it completelyinstalled in 5 to 10 minutes without any soldering involved. :D

[Maple Hill Sugarhouse]

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[WESTVIRGINIAMAPLER]

I don't plan on soldering in a place for one. I may stick a thermometer in the float box from time to time to get an idea, but that's good enough for me. Enough expense is enough. :lol:

[Maple Hill Sugarhouse]

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[SUGARSMITH]

Would a smaller diameter pipe, say 1/2 or 3/4 in a continuos circuit get greater temperatures or is the 1-1/2 inch necessary. I dont think there would be a issues feeding the back pan with the smaller diameter

[WESTVIRGINIAMAPLER]

I think the larger the pipe, the higher the temps of the sap if you were running the same footage because the larger pipe has more surface area. That may not be the case however as a smaller diameter pipe may make more contact with the sap as it is in a smaller enviroment. In my evaporator, 3/4" is what it calls for and it is a lot cheaper than larger sizes. It is much easier to find 3/4" fittings also, but in an evaporator your size, you may want larger.

More smaller pipe would probably heat better if ran in a continuous flow, but I wouldn't know the answer to it. I would think it would be wise to stay away from 1/2" pipe on any evaporator larger than 2' and probably a good idea to stay away from it period. This would be due to the fact that there is a ton more liquid in a 3/4" pipe if you needed it in a hurry. :(

[WF MASON]

I've always used 2''copper pipe in preheaters, a 1''feed in and 1''flow out, the idea being ,a large volume of sap is heated and moves slower through the 2''giving the sap time to preheat, I will be trying one out of 1 1/2'' copper soon with the same idea , slow the sap. I know the 3/4'' does work through.

[brookledge]

You should stay away from the real small sizes because if you need sap in a hurry to save from burning or low level the small diameter pipes will not flow very fast. When you add more length from the supply tank to the evaporator by adding a pre-heater you increase the friction loss resulting in less gal per min. As with most of us our supply tank is not much higher than the evaporator so you don't have a lot of pressure. Pre-heaters should try to be sized according to the evaporator. Most manufactuers have done this and will sell you the size you need. If you want to make your own see if you can look at one or ask what size is recomended.
The key thing is: Too big of a pre-heater will cause either vapor lock or vent out the top and sometimes not allow the float to work properly.
Too small and sap will be still cold.
Keith

[WESTVIRGINIAMAPLER]

If anyone is interested in a hood like mine or a different design, the amish who made my hood is good friends with my dealer who is also amish. My dealer goes up to Leader and the other evaporator companies at least a couple times each year and normally rents a tractor trailer and hires a driver to drive him up.

On the way up, he usually has room to haul items and I am sure he would be glad to haul up a hood to VT or NH for a nomimal fee if anyone is interested. They are both really great to work with! :D

Aprox price of a hood system for a 2x6 = $ 350

Aprox price of a hood system for a 2x8 = $ 440(what I paid for mine)

4' section of 10" stainless steam stack was $ 30 per section with a built in damper.

stainless roof jack with large base for $ 40.

I think he is coming back up in Nov or Dec if anyone is interested, let me know.

test run your hood yet? Jacob

[WESTVIRGINIAMAPLER]

Jacob,

I haven't had time yet to do a test boil. I still have a few hours work finalizing everything and then I will do a test boil. I plan on sometime next month, probably around Christmas, maybe Christmas eve. :D :D

I will be sure to let you know when I do! :D :D