Drop or raised flue

[ebourassa]

I am looking in to buying a 2x6 for next year I was just wondering which one was better and why, Drop or raised flue. any suggestion would be greatly appreciated. Thank You

[powerdub]

This question reminds me of the great Ford or Chevy question. It all kinda boils down (no pun intended) to your personal preferance. I have used both and prefer a raised flue. Some say a drop is more efficient but I did not find that to be true, they seemed to be the same. The reason I like the raised is if you get into trouble and need to flood the front pan in a hurry you can knock the floats out and you have enough sap to fill the front pan. That is not the only reason but it's the one that comes to mind right off. :roll:

[WESTVIRGINIAMAPLER]

I have never boiled on a raised flue, but I really like my new drop flue 2x8. All the pipes and connections inside it are all 1.5" inside diamater stainless pipes, so I don't worry too much about liquid moving to troubled spots too much because if I would get in too much trouble, I would hold down the intake lever and the liquid would get to any place in the evaporator in a hurry. My evaporator is a Leader, so I don't know if the other manufactures use as big of pipe connections. They sure comes in handy if I need them!

[WF MASON]

Look North, young man, Look North, them Canucks make and USE raise flue evaporators for a reason !!!

[Salmoneye]

I just hate the 'look' of a raised flue...

Salmoneye, The Traditionalist

[Breezy Lane Sugarworks]

I have a raised flue and love it. People have told me that the raised flue is better because heat rises and gets trapped up in the flue channels. Where a drop flue the heat just slides along the bottom of the pan and up the smoke stack.

[ebourassa]

I think next year I will buy the raised flue, my uncle in canada who used to run a 5000 tap sugar house told me that the raised flue is suppose to be better because the heat rises. He had 6x16 evaporator raised flue. Well keep your opinion coming, I love to read them.

[sugaring42long]

One advantage of a drop flue is that it holds less sap than an equal size raised flue. This reduces the amount of sap being boiled at any given time and increases the turnover through the pan. Some say this helps make lighter syrup with marginal sap, Same theory as running as shallow as you dare.
I have used both styles and find the drop flue to be less forgiving with boiling depth ( easier to burn ) but also easier to make light syrup on.

[RUSTYBUCKET]

My plan for this year is to sell my current evaporator and move up to a 2x6 for next season. I've read the posts here about drop vs raised flue but I would like to hear from you folks as to what your current evaporator is (drop or raised) and why you chose it, i.e. price, looks, neighbor has the same unit, parts replacment costs etc..

At present, I have the D&G Sportsman. Our usual procedure is to drain the sap pan after every boil. Due to the size of the unit, its managable with one person but two is better. I'm interested in the D&G model 500 2x6 one reason being, going by the picture in the catalog, the sap pan has handles and what looks like a sap pan drain. I can't verify this because I've never seen one in person. This would be one feature that could factor into my decision to go with this unit. Just looking for some brain fodder to help make my decision.


Russ

[WF MASON]

I've seen alot of frozen and leaking drop flue drains over the years ,so I perfer raised flue, But D+G
makes their drop flues with a 45'angle on the fire box end , so the wood is deflected if it hits the flues. Also D+G makes their drop flue drain out of hevier gauge stainless then the flues are made of, so the chance of splitting from ice or damage is less. Also the bottom of the flue is slotted the width of the drain box , about 2'', not just a drilled hole , this allows NO chance for the sap to burn in the drain box, darking and flavoring the sap. The end caps on the flues are not just welded on, but are inset about 3/16'' of an inch , making the ends much stronger.
From a sheetmetal standpoint , D+G has done their homework and then some. Its been about four years since I've had the chance to look at one of their drop flue pans and I would think the quality would only get better. If money is no restrant , they make the best.

[WESTVIRGINIAMAPLER]

I have a drop flue and like it a lot. It is simpler to use than a raised flue, but I think a raised flue would boil faster simply because heat wants to rise and it goes up into the flues and traps there to a certain extent.

It does sound like D&G make the best drop flue pans, because Leader does not do that much work on their flue pans. My drop flue pan is of extremely high quality and I am very happy with the quality and the workmanship is great. As far as looks goes, I believe Leader makes the prettiest pans not that it really matters and they put some nice design features.

My flue pan drain is extremely heavy walled stainless, probably 2 or 3 times thicker than the flues. My pans are welded and are 20 gauge, so they are heavier than most others which may even affect the boil rate a touch over a 22 gauge pan.

[WESTVIRGINIAMAPLER]

The statement was made earlier that raised flue evaporators are the best because that is basically what every Canadian company makes and we should look north.

One of the main reasons that most companies make the raised flue evaporators is that it is a lot easier and a lot less time consuming to make a raised flue pan versus a drop flue pan. This means the prices are quite a bit cheaper and most people want the best price and companies want to be able to make things as fast as possible.

If I ever buy another evaporator, it will be a raised flue simply for the fact that I think it will have a slightly higher evaporation rates. Most of the experts that I have talked to over the past year or so that have used both and are very familiar with both say a drop flue will boil faster. I am not the expert, but I would have to disagree with that statement.

In general, a raised flue pan will last longer than a drop flue.

[brookledge]

in repsonse to Brandon's last comment I was told by a leader rep along time ago that in the narrower rigs you have the same amount of flues but in the wider rigs they can put more drop flues in then they can with a raised flue. Therefore giving the drop flues more surface area for heat transfer causing a higher boiling rate. I boiled on a drop flue for over 20 years. I bought a wood fired 3X12 revolution raised flue 2 years ago with an inferno air tight arch and i get 140 gpm on it I know for a fact that the drop flue would have cost me alot more money I think the leader rep told me that 5' and up have more flues in the drop style. Another big factor is the depth of the flues Some manufactuers use 5" some 7" and some 7.5" remember that the total amount of surface area exposed to the heat is the bigest factor in evaporation rate. On smaller rigs I would recommend a raised flue. I have boiled with both types and feel that since the price on raised are so much cheaper thats the way to go

[RUSTYBUCKET]

Thanks for all the replies. The last post touched on the subject of longevity. As a hobby, we've been cooking tree juice for about 15 years, the first 10 on a flat pan making about 1 gallon of syrup/10 hours and the last 5 years using the Sportsman.

After this year, I'm going to replace the grates (they are usable but beginning to warp) and the smokestack, which is galvanized. Other than that, my unit has been trouble-free.

For all you long-timers, how many years can one expect out of an evaporator? Other than the grates and smokestacks, what other parts need to be replaced over time? If an all stainless 2x6 with steam hood ends up costing me $3-4K and last 10-15 years, thats a reasonable $$$$/year hobby cost to me.

Russ

[RUSTYBUCKET]

Whoops, brookledge got in a post on me. My comment about the topic of longevity refers to the "guest" post.

Russ

[brookledge]

if you are buying a new one well worth the money to get stainless sheet metal in the arch and stainless base stack and smoke stack. if you can aford also get welded pans. I had my last one for 15 years 3X8 dropflue when I sold it it still had many years left in it. Seems like you alway want to get a bigger rig before the one you have wears out. Another factor in longevity is maintainence. just like anything else

If you put arch board or ceramic blanket under the bricks especially on the sides and bottom ramp, the arch will last a lot longer. A dry building to keep it in too helps. If you don't burn a pan, I would think 10-15 years easy. There are older ones than that being used.

[WESTVIRGINIAMAPLER]

I would definitely agree with it being all stainless. People often buy the arch and stack in galvanized to save a few bucks and have to replace it a few years later. I am not sure how long a stainless stack and arch will last as they have not been out there long enough to know, but I have been told by the manufactures 30 years. If you get it all stainless and get a good quality set of welded pans, with proper care, I would think any evaporator would last at least 30 years.

The advantage to soldered pans is that they will boil a little faster because they are lighter gauge stainless, but I think the advantages end there. :?

[rob]

Hey Rustybucket,

-If you do decide to sell your sportsmen drop me an e-mail please, I think that is what my wife and I want to start using instead of cinder blocks and canning pans
rrm_thomp@hotmail.com

[WESTVIRGINIAMAPLER]

I do believe on a large drop flue that they may outboil a raised flue, but on smaller sizes that about all of us use, a raised flue is better.

That is what I was interested in, not a large model and didn't get what I wanted in info. I do find that interesting about the info that a raised flue will last longer. I guess I never thought about that.

You learn something new every day and a lot of things on this website.

[RUSTYBUCKET]

Brandon,

WOW, 30 years use from an evaporator!! Now I finally have something of real value I can put in my will :wink: !


Russ

[Fred Henderson]

I can assure anyone that stainless steel can be solder. When I made my evaporator I used the small left over pieces to make the scoops & skimer. So just for the fun of it I tryed soldering one. Mind you now it is special solder made for stainless but will also wok on steel.

[WESTVIRGINIAMAPLER]

On Leader evaporators, the welded pans are 20 gauge and the soldered are 24 gauge. I don't know if anyone else still makes soldered pans or not :?:

[WESTVIRGINIAMAPLER]

On Leader evaporators, the welded pans are 20 gauge and the soldered are 24 gauge. I don't know if anyone else still makes soldered pans or not :?:

As far as I know, the soldered pans Leader makes are all stainless steel with lead free solder.

[WF MASON]

There is a big difference between 20ga. and 24ga., the thickness is like holding a dime in one hand and an nickle in the other. The thicker the steel , the easier to weld.The less heat transfer , I'm not sure if thats in the customers best interest in this particular application. Perhaps lack of skilled labor and ease of manufacturing would be just two reasons for companys still to be welding 20ga. stainless.

[WESTVIRGINIAMAPLER]

Bill,

Would the 20 gauge stainless be more durable than 22 gauge since that is what most companies are using??

[WF MASON]

Durable , um, well the argument could be made a number of ways. 24ga.english tin pans we've all seen in use, and some are still using today ,were made back in the 40's- 50's and before. I'd have to say they'd be concidered durable, and I've see sugaring pans made of 18ga. stainless that will be here long after were gone. I'd concider thoese durable also. The question is , 20ga stainless is more durable then 22ga. , in the application for which it is used , setting on an arch with sap in the pan boiling. I'd say no. If you were going to build an arch , you'd want the heaver gauge for strength.
As for all companies using 20ga. stainless in there pans, I believe most would disagree.

[WF MASON]

I'm thanks for the kind words , but generally what I express here is 'opinion' , I'm an expert at nothing.

[WESTVIRGINIAMAPLER]

Bill,

I know Algier and maybe others offer their pans in either 20 gauge or 22 gauge stainless. I would like to know for sure why that is?? I have always wondered for sure and I wish someone would experiement and measure in percentages the difference in evaporation rates with say and oil fired setup so it would be accurate. Leader says there is no difference at all between the 24 gauge soldered pans and the 20 gauge welded pans, but I think they are STUPID! :roll:

[ontario guy]

as far the soldering 304 stainless pans go, yes you can. All you need is special flux and you can solder with a propane torch and soft solder (the kind you use for household copper pipes) I have made a small test pan and it works beautifully. ( the asthetics of my soldering leaves something to be desired though) As for durability, i think all pans will last the same time as long as they are not run dry. Afterall the temperature of the pan never gets above 217 derees (boiling point of syrup) so at that temperature there is no danger of the solder melting (melting point 475 degees)
Stainless is a very bad conductor of heat so i would say that the thinner stainless would boil faster, but maybe the difference is negligible. Copper is 10 times better at conducting heat, tin in about 8 times.

just my 2 cents.

Mark

[WESTVIRGINIAMAPLER]

It is a shame that we can't make pans out of aluminum because the evaporation rates would probably double.

Some of the companies were making pans out of 430 stainless for a while, but I guess that didn't last because 430 has even more Chromium and is even worse conductor of heat.

[Fred Henderson]

I went to a local maple conference this past Jan. And an Algier company rep told me that they used to use that 430 but that I would not stand up under all the heat.