Pre Heater

[tonka]

Hello folks! So I'm planning on building a preheater like the one from Sunrise Metals http://sunriseevaporator.com/wp-cont...ndex.html#p=17. I've read some threads on here talking about vapor lock, with this style of preheater, is this something that I need to worry about? I only notice 1 inlet and 1 outlet, no breather.

[johnallin]

Not sure how that particular unit works, but my leader pre-heater has a box manifold at ea end.

The upper end then has a 5/16" vent pipe at the top to which I clamped a 6' length of 5/16 tube.

Should any pressure build up; this empties into the head tank.

[maple flats]

You should have either a vent valve or a tube (going to the head tank or the float box) on each opening on top of the pre-heater to vent air if needed. Much of the need will depend on a few factors like the head of sap (or concentrate) above the outlet and the design of the connections and piping from the pre-heater to the inlet float box.
I built my own pre-heater out of copper tubing and I have 4 vents on my pre-heater. My head tank bottom is about 16-18" above the outlet on the pre-heater and from there the piping has a slight drop until it gets over the float box. There it drops straight down and then ells to enter the float box which is valved. I have never needed to open the vents. That being said, I would never assemble one without vents.

[Mead Maple]

Clicked on the link that tonka posted. Also checked out the one on Smokey Lake's website. Seems like if you could solder pretty well, add the suggested venting ports, and couple that with a steam hood, you could be upping your evaporation rates in no time. I might seriously consider building one when the time came. I think without a hood you're not going to gain enough evaporation rate to pay for the copper but with the hood I think it could gain your some miles per hour

[maple flats]

They really need a hood. Over the years I had 3 different evaporators, a 2x3, a 2x6 and my 3x8, on each I made a hood out of aluminum sheet and all 3 worked well. Then for my current arch I bought a new set of pans (with an RO I needed less flue pan and more syrup pan. The original was 3x2 syrup and 3x6 flue, now I have 3x3 and 3x8) When I ordered the pans I asked the price for the hoods and they said $1950 so I said I'd make my own. When I went to pick up the pans they asked if I had made the hoods yet. I found out they had a very slightly damaged demo unit and wanted $800 for it. Looking at it, the dents were almost un-noticable so I bought the hoods, with 2 steam take offs and the first 4' of 15" SS stack. That hood is better than any I made but my homemade ones always did their jobs. #1 however had no gutter nor pre-heater, #2 & 3 had both and looked good too.
You can make a hood using aluminum roof flashing or sheet aluminum and pop rivets. I used an aluminum trim brake to make the bends.

[tonka]

I'll have to check out smokeylake preheater. I have a steam hood made out of 20 ga stainless. I've done some looking before building a preheater and one thing that sticks out the most is having a pressure release valve/pipe to prevent vapor lock. I noticed only 2 inlet/outlet on the link so that's what made me post about it. From my understanding, the U shaped preheaters the cold enters on the bottom run and gets pushed up around the bend and through the upper run of pipe then out to the float box, trying to avoid any vapor lock this way, is my understanding correct?

[Mead Maple]

They really need a hood. Over the years I had 3 different evaporators, a 2x3, a 2x6 and my 3x8, on each I made a hood out of aluminum sheet and all 3 worked well. Then for my current arch I bought a new set of pans (with an RO I needed less flue pan and more syrup pan. The original was 3x2 syrup and 3x6 flue, now I have 3x3 and 3x8) When I ordered the pans I asked the price for the hoods and they said $1950 so I said I'd make my own. When I went to pick up the pans they asked if I had made the hoods yet. I found out they had a very slightly damaged demo unit and wanted $800 for it. Looking at it, the dents were almost un-noticable so I bought the hoods, with 2 steam take offs and the first 4' of 15" SS stack. That hood is better than any I made but my homemade ones always did their jobs. #1 however had no gutter nor pre-heater, #2 & 3 had both and looked good too.
You can make a hood using aluminum roof flashing or sheet aluminum and pop rivets. I used an aluminum trim brake to make the bends.

Flats, with the “gutter” system you are talking about I would assume that means for condensation to collect off the walls of the hood. Did you bend these in addition or build them and rivet them on? You don’t have any old pics kicking around do you?

It’s a bitter sweet thing because I’m such a fan of watching things boil and the kids love that sweet steam


Sent from my iPhone using Tapatalk

[Mead Maple]

They really need a hood. Over the years I had 3 different evaporators, a 2x3, a 2x6 and my 3x8, on each I made a hood out of aluminum sheet and all 3 worked well. Then for my current arch I bought a new set of pans (with an RO I needed less flue pan and more syrup pan. The original was 3x2 syrup and 3x6 flue, now I have 3x3 and 3x8) When I ordered the pans I asked the price for the hoods and they said $1950 so I said I'd make my own. When I went to pick up the pans they asked if I had made the hoods yet. I found out they had a very slightly damaged demo unit and wanted $800 for it. Looking at it, the dents were almost un-noticable so I bought the hoods, with 2 steam take offs and the first 4' of 15" SS stack. That hood is better than any I made but my homemade ones always did their jobs. #1 however had no gutter nor pre-heater, #2 & 3 had both and looked good too.
You can make a hood using aluminum roof flashing or sheet aluminum and pop rivets. I used an aluminum trim brake to make the bends.

Flats, with the “gutter” system you are talking about I would assume that means for condensation to collect off the walls of the hood. Did you bend these in addition or build them and rivet them on? You don’t have any old pics kicking around do you?

It’s a bitter sweet thing because I’m such a fan of watching things boil and the kids love that sweet steam


Sent from my iPhone using Tapatalk

[maple flats]

For the gutters I bent the bottoms inward and up, then siliconed the corners and the drain. That was on all but the last one I made. On that one I bought some aluminum channel, 1x1x1. I mitered the corners and using a map gas torch and some aluminum rod, I welded the miters (pretty much like brazing). Then I pop riveted it to the bottom of the hood. At the drain, I cut one 1" side out, then added a 3-4" long piece of the same channel and welded that too. In use I discovered it would have been far better to have angled the drain down a little. The drips kept running back and down the side of the pan. I then bent the outer edge of the channel using heat and pliers, but it was not fully right until I put a band clamp arount the channel to give the drips a place to fall into a bucket. If you make one, cut the drain spout to attach at a 5-10 degrees slope and there will be no issue. The channel stock I used was 1x1x1 of 1/8" thick stock.