Adding fins to bottom of flat pan (?)

My 2x4 homemade rig has one large flat pan, and I'm getting about 7 to 8 gph evaporation. I really want to increase my evaporation, but I'm struggling to afford a real flue pan or a commercial evaporator.

In place of getting or making a flue pan, it would be relatively easy/cheap for me to add heat fins to the bottom of the flat pan. For example, my pan right now is 19" deep. I can cut it down to 9" height, and use the cutoff material to make 1" wide by 48" long fins. I'd then weld the fins vertically to the bottom of the pan. The bottom of the pan would then have several (dozen?) of these strips that ran along the length of the pan.

Kind of like electrical transformers use heat fins to remove heat, I'm hoping the added surface area in contact with the flames will increase the heat transfer to the sap - and hopefully improving my efficiency.

Anyone try something like this?

Problem is you would have all the hot spots running across the bottom of your pan. Would be okay when boiling sap but when you get to the syrup stage you would be in trouble.

Stewie,

Adding the fins would have a very small effect on the evaporation rate. Especially if your pan is stainless steel. Stainless has relatively poor thermal conductivity, which is why it's important to use very thin sheet in pan construction.

You would be way ahead putting your effort into increasing the area exposed to heat on both the wet and dry sides. That means adding flues. The easiest way to do that is the copper drop tube flues discussed before. Each tube adds about 18 square inches of area!

If I can find another SS pan this summer I want to try the drop tubes. I can.t find the hammer arrestors here so will have to try tubeing and either close the end off or caps. That for me will be the easiest way to increase the surface area.

Neat idea; never seen/heard of that before.

I see the hammer arrestors at the local hardware store before, but they're a bit pricey. Any concerns with taking standard coppper pipe and soldering on a cap?

Anyone have data on "before" and "after" drop tubes with respect to evaporation rate?

Also, how do you clean those buggers out?

My first drop tubes used caps. They work fine but are difficult to solder because you have to put the caps on after the tubes are dropped in if you flange the tubes.

Adding the tubes easily tripled the evaporation rate of my steam table pan.

Cleaning is easy: Coat hanger wire, tuft of scotchbrite, cordless drill. Rinse well.


When soldering copper to stainless, use good liquid flux and a very low flame. Tin each side first.

Have fun!

I have often thought that 1" copper pipes w/end caps would be an easy way to add some poor-man's flues to a pan. It even seemed like you could cut some slots in the top end of the pipes and bend them out flat (horizontal) to create tabs that you could solder to the pan.

It would only work on pans small enough to flip over to drain

If you use copper tubeing would you use the soft stuff or the hard pipe. I was thinking of useing soft tubeing and then just bend the ends over and hammer flat. Would be quick and sure fire not to leak. Will have to price this out this summer. Now to find the liquid flux. I can find non lead solder paste pretty easy.

Quote:

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Originally Posted by RileySugarbush

My first drop tubes used caps. They work fine but are difficult to solder because you have to put the caps on after the tubes are dropped in if you flange the tubes.

Adding the tubes easily tripled the evaporation rate of my steam table pan.

Cleaning is easy: Coat hanger wire, tuft of scotchbrite, cordless drill. Rinse well.


When soldering copper to stainless, use good liquid flux and a very low flame. Tin each side first.

Have fun!

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DO THESE TUBES DROP DOWN ON THE UNDERSIDE OF THE PAN TOWARDS THE FIRE/SMOKE CHAMBER? IF SO IS THERE ANY SPECIAL SOLDER THAT YOU NEED TO ACCOMEDATE THE HEAT?? THANKS I TOO HAVE A FLAT PAN AND WAS THINKING OF INCREASING MY EVAP RATE, THIS SEAMS ALOT EASIER THEN ALLTERNATIVE, CUTTING SLOTS FOR FLUES AND DROPPING THEM IN..

Ken

I have used water hammer arrestors and copper pipe for water service/caps. Even the hard copper can be squeezed flat and soldered if you want to do that.

Rookie, I used silver solder, but any lead free solder would work. I think the key is to clean the metal well and use good flux and the right flame. Practice!

Yes the tubes drop down into the flue, but the solder doesn't melt because the tubes are full of sap which limits the temp to the boiling point, just like in other soldered pans. Don't run them dry!

ok so if i got this right, i have a 24in pan, i would drill a series of whole front and back run pipe down to the hammer arrestor and a pip to the other end two another arrestor wich then another pipe would complete the run back into the pan at the opposing end.. if this is correct coulde i use 1in pipe and keep them 1in appart?? and how much evap increase do you for see me getting out of a 2ft x 4ft pan with say 20 of these drop tubes??
sounds like an awesome idea..

Maple Rookie. You drill 1 inch holes in the pan or better yet cut them and flare the top of the water hammer arrestor and drop it thru the hole and solder it in. it is just a tube dropped down the few inches in length of the arrestor. The sap basically boils in the tube faster since it is copper and attacts heat better and drops down so the whole circumference is exposed to the heat. You can also use one inch tubeing and either cap the end after you drop it through the hole in the pan or squeeze the end shut on the tube and solder it and then drop it through the pan. The pictures of the process explain it a lot better.
Another idea brought up was to drop the tubes down through the pan and attach two of them toghether with a short peice of tubeing and elbows. I am thinking you could then run less tubes through the pan and rely on the surface area of the connected tubes to heat the sap. What I also wonder is just how hard the sap boils up out of the tubes and if it splashes a lot. I can see mini geysers all over the pan. Riley might know the answer to that.

After searching for water hammer arrestors all over I have found they don't sell them up here. The only ones we have here have a piston in them and sell for close to $90 bucks. Will have to use pipe as they don't sell 1 inch tubeing up here either I am told. I have another idea also if I can figure out how to cut 2.5 inch holes.

find a guy that has the hole punch kit that they use to cut into elec panels. The only reason I have one is I found a complete set of them on the side of the road. They will cut/punch a perfict hole every time. Using a hole saw will only get you a sloppy over size hole that will piss you off. The reason that hole saws cut such sloppy holes is the sheet metal cant keep the pilot drill in place because it wallows out as it cuts. There is a trick but its a bitch to do if you drill thru the sheet metal and then into a thick block of steel with the sheet metal clamped onto the block of steel you can get a better hole slow slow slow oil oil oil

I tried to find a Greenlee punch up here and no dice either. I think they use another name for them up here. Can find them on US web sites. I used them years ago when I did electrical work and the electricians still have them but how the find them beats me.

Sorry I haven't been paying attention...


Ken has it right regarding the drop tubes. Click on my name and select "visit homepage and you should be able to find a bunch of photos of how I made my drop tube pans.

Any sheet metal shop should have Greenlee punches or equal. Even in Canada.

The sap does jump out of these vigorously!

check mcmasters.com or grainger.com for greenlee punchs.there both maintenance supply com. and i no at one time they both carried them!

Quote:

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Originally Posted by SPILEDRIVER

check mcmasters.com or grainger.com for greenlee punchs.there both maintenance supply com. and i no at one time they both carried them!

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Thanks Spiledriver. Turns out the other name for them is a knockout punch which is waht they call them up here. I needed another name for them inorder to find them up here.

I have used "step drill bits" with good results to put darn near perfect holes in sheet metal. Installed a port for a thermometer in my half pint pan with one last year and it worked great.

Just make sure you back the pan up with a piece of wood (2 x 6 or close), keep the pan and the wood clamped together nice and tight and the bit will bite into the pan and the wood without wobbling. With some practice you should have some nice round holes.

Should be able to find one for less than McMaster Carr prices but here is link

http://www.mcmaster.com/#step-drill-bits/=22ky8e

I have the step drills already and if I could not rent a knockout punch would have resorted to useing it instead. The best place to buy stuff like the knockout punchs closed May 13 up here and I haven't found another outlet for them yet. I can also use a 1 inch drill bit if I use wood or two peices of steel with 1 inch holes drilled in them as guides.

A fellow at a garage sale gave me another SS sink this weekend so I am half way towards my new pans now. I just have to get one more then figure out the drop tubes for at least one of them and I am away. I have a couple of ideas on them. One is to make only 6 drop tubes but to connect two together underneath with a cross tube so as to increase the surface area. Also for the drain hole I want to solder in a SS cup into the hole to increase the surface area. Will see how it goes if I can find one more sink as those resturant pans are non exsisitent around these parts except the shallow ones.

Hey ken with the amount of taps you kept adding this past season get yourself a 2x6. I can just imagine how many you are gonna add next year. It all starts with 30 then 150 then 300 and like the energizer bunny it keeps going and going and going.:mrgreen:

Riley what size Greenlee punch did you use. The copper pipe measures 1 and 1/8 inch around here. I almost bought a 1 inch punch off Ebay untill I stopped by the Quincaillerie and measured the copper pipe and found out how much over a inch it was.

Ken,

I'm with 3rdgen. The amount of taps your talk'in about might require more than steam table pans. You can make a drop tube out of a flat pan. You add stainless tubes horizontaly through the pan. All flame and gases go through this. Lots of boiling capacity. I think WF Mason makes these.

I have no idea where a person could buy SS tubeing let alone anything else SS. I finally found a guy who could tell me where to even buy steel around here. I am basically trying to get by with what I can find around here. I grew up in the oilfeilds and metal and all that good stuff was all around me but in this part of the country the selection just dosn't exist.

Ken do you have any scrap yards around you, if they exist there check with the transfer stations (local garbage dump) The usually have a metal recycling area where people drop off there junk to them metal. There are a million websites to get metal from also. Guess everything depends on the ole budget. Keep looking you will find the mother load and then the boss of the house will be mad cause of all the goodies filling up the garage.

Well found another SS sink today so I can start on my updates. I still have to figure out how to cut the holes in the metal but if all else fails will drill them out and then ream to the right size afterward. I know you guys figure I am nuts but my Grandparents came from Penn and Iowa so that expalins it pretty easy I hope.
Now to find thin wall copper tubeing.

I recall it being one inch even. Certainly it was a free but close fit around the OD. I then flared the copper 90 degrees for the solder joint.

There is chance the arrestors are 1 inch even but the tubeing is 1 and 1/8 od. I will figure it out. I even found a chunk of aluminium today to make the die for flareing them.

Just a dumb question here but why does it have to be an inch. Would it not be easier instead of searching all over maple country to find the copper pipe you are looking for and just go to the hardware store and by what size they have on the shelf. 1/2 inch ,3/4. I know you are thinking surface area but smaller pipe means more holes which means surface area. Get a 10 foot section of copper waterline and some caps. Cut, flare the top, drop in hole solder cap on and solder to the pan. Thin wall, thick wall whatever copper transfers heat very well and either one is gonna increase your evap rate. Ken I don't think you are stupid be proud man and do what you are capable of and enjoy the hell out of it.

Ken you have inspired me to upgrade my back SS sink pan as you are doing. My pan is 15x 21 and is now marked with 15 one inch circles which I will start to punch out with a Greenlee punch, flare, and soldere in place.
Made a test piece with a scrap piece of SS and it went quite easy. The key to easy soldering is in the proper flux, which needs to be acid based.
I am making my drop tubes 3 inches long which will add about 9 square inches of surface area each, or 135 added to the 325 inches of the flat pan. I suspect it should really give my rear pan a real shot in the arm.
The only concern I have at this time is, what effect of it may have on the pan in terms of warping when I put the fire to it.

Rick

Already thought to go to 3/4 as that,s easy to come by in the hardware in town and I have the tools already to drill holes that size. The 1 inch is a problem to find here for some reason. I am thinking to much on heating up a 3/4 inch tube might cause the sap to spout up to much.

Ken,

I found a left over scrap and my copper tubes were about 1.125 OD, like yours.

3rdgen,

No reason to avoid other sizes. Rather than caps, if i was doing this again I would flare one end, solder in place, pinch and solder the bottoms. Cheaper than caps.

Rick,

I'd make them longer if you can. Mine were 6 or 7 inches deep and worked great. Liquid acid flux, clean surfaces, low heat and tinning both surfaces firs made soldering (almost) easy. The bottom of the pan remains unwarped.

I'm looking forward to seeing how you guys like the flue tubes. I sure did!

I am thinking of adding a manifold to the bottom of the drop tubes by using Tees with elbows on the first and last in each row. Using 1" copper, 3" Drops. Does anyone know if by adding manifold to the drops will the sap make geysers at each hole opening?

I was thinking of Drop Tubes with a manifold connecting all the drops. Now rethinking maybe 2" Copper thru the pan end to end 1/2" off bottom. Re thinking because Tees are 8 bucks a piece and 10 holes to solder are easier than 50. 2" Copper is 145.00 per 10' Length
2 lengths will give 5 thru tubes in 4' flat pan. 5 Tubes will add 1508 Sq" of area to pan. Current pan size is 28" x 48" (1344 Sq"). If I calculate right that should give 112% better boil rate. Has anyone ever tried thru flues? Basically the way I am thinking is that they are just like drop flues but are attached on the end of the pan and flue gas is directed into them and out the back of the pan as well as going under pan. Any ideas will be appreciated as I would like to get started soon.

Martin
1st yr 5 taps 2 steam table pans
2nd yr 20 taps 4 steam table pans
3rd yr ?? Maybe 50

Here is a cool drop tube evap from along time ago I found it by doing a search for patents at Google Patent.

It is kind of cool that it uses the tubes as the grates.

That's sort of how a old coal frired boiler worked. Was made of hollow plates in a square and the coal burned in the middle. I took many of them apart out of old CPR train stations .

I wonder how well new sap would replace the soon to be syrup. I think the tubes could vapor lock and you would get scorching.

MartinP,

Drop tube evaporators are made commercialy the way you are thinking (horizontal). I believe WF Mason makes them. I know a guy who has one and loves it. It might be had to find, but price out a 20' length of stainless. I bet it would be cheaper than copper. You would need a plasma cutter to cut, but it would be easier to clean.

Makng tubes connected on the ends was my dea also as it would requre less holes to solder up. I would lke to use SS tubeng but who knows where to get it around here also. I used to use it in half inch water pipe for years but its expensive.